WO2001058067A1 - Clock synchronisation in a network and network users, in particular a field device for said network - Google Patents

Abstract

The invention relates to a network with several network users (1, 2, 3, 4, 10, 11, 12). A first network user sends a time of day, corrected for the send-time delay, to a second network user, in the form of a message for clock synchronisation. The processing time for the physical transmission is registered in the second network user, which corrects the received time of day, by the processing time and the receiving-time delay. An improved accuracy of clock synchronisation is thus achieved.

Description

_O ^ _TT ^ _{T. ^} TIME SYNCHRONIZATION IN A NETWORK AND NETWORK SUBSCRIBER INSBE

SPECIAL FIELD DEVICE, FOR SUCH A NETWORK vvn ^Ki - ⁱⁱ ^ ^f cHMfcK, 1NSBE-

The invention relates to a network according to the preamble of claim 1 and to a network participant, in particular a field device, for such a network.

Such a network is, for example, from the

DE 197 10 971 AI known. In a network with a plurality of network participants, for example sensors and actuators, which are connected to one another via the network for data transmission, synchronization must be carried out for time-critical applications, for example for simultaneous measurement value acquisition during control processes. To synchronize the participants, a participant sends a telegram to the other participants, which can be used, for example, to cause certain participants to simultaneously acquire measured values.

It is taken into account that during the transmission of telegrams between transmitter and receiver, lead times occur over the physical transmission path, which are determined, among other things, by the distance and the physical transmission speed of the signals on the transmission medium. So that the running time differences of telegrams to different participants do not have a negative impact on the synchronization accuracy, the running times are automatically recorded by a telegram sequence. In m networks in particular, whose topology and spatial extent can be changed, automatic determination of the throughput time has advantages. Changes can occur, for example, if participants are only connected temporarily or at different locations. One way of synchronizing the participants is for a participant to transmit his time in a telegram to the other participants. The previously determined throughput time of the Telegram is stored in the other participants. These correct the time received in the telegram by the respective transit time of the telegram and in this way synchronize their internal clock with the time of the transmitter.

The object of the invention is to create a network and a subscriber, in particular a field device, for such a network, which are characterized by improved accuracy with regard to time synchronization.

To solve this problem, the new network of the type mentioned has the features specified in the characterizing part of claim 1. A network participant, in particular a field device, for such a network and advantageous refinements of the invention are described in claim 11 and in the dependent claims.

The invention has the advantage that a transmission time delay in the transmitter and a reception time delay in the receiver, which can be variable, are taken into account in the time synchronization.

For this purpose, a first network subscriber sends a first telegram to a second network subscriber, which contains the time of the first network subscriber corrected by a transmission time delay. The telegram transit time is stored in the second subscriber as a throughput time over the physical transmission link between the first network subscriber and the second network subscriber. For example, it can be entered manually or by another

Telegram traffic must have been measured beforehand. The second network participant measures the time delay since receipt of the first telegram and corrects the time received in the first telegram by the throughput time and the measured reception time delay. The second network participant is therefore advantageously able at any time to obtain a synchronized time from the sum of the time received in the telegram and to determine the delay in reception time supplemented by the transit time. Variable transmission and reception delays have no effect on the result of the synchronization.

If the second network participant is also designed to send a second telegram for time synchronization to a third network participant, which contains a received time corrected for the running time and the delay time between receipt of the first telegram and transmission of the second telegram, then iterative forwarding of the respective one corrected time from network participants to network participants possible. Identical correction mechanisms can be applied in the receiving network participants. The runtime stored in each case in a network subscriber corresponds to the runtime over the physical transmission link between the last sending and receiving network subscriber.

As an alternative to sending a telegram for time synchronization from a first network participant to a second, time synchronization with two telegrams can also take place. For this purpose, the first network participant sends a first telegram for time synchronization to a second network participant and at the same time stores a time of the first network participant corrected for the transmission time delay. The transit time of the telegram is stored in the second network participant over the physical transmission link between the first network participant and the second network participant. The second network participant measures the time delay since receipt of the first telegram without, however, stopping the timer used for this. The first network participant now sends a second telegram, which contains the time of the first network participant corrected for the transmission time delay, to the second network participant. The second network subscriber corrects the time received in the second telegram for the runtime and the Reception time delay, which is measured in relation to the reception of the first telegram. This procedure with two telegrams has the same advantages that are also associated with the procedure for time synchronization with only one telegram.

For a network with more than two network participants, the process with two telegrams can also be continued in an iterative process. For this purpose, the second network participant forwards the first telegram to a third network participant and measures its delay time for the telegram forwarding. In a third telegram, the second network participant sends a received time to the third network participant, corrected for the running time and the delay time of the telegram forwarding of the first telegram.

The actual transmission time delay in the time synchronization is advantageously taken into account if the first network subscriber has a first timer for determining the transmission time delay, which he starts a list of the transmission orders when a telegram m is entered and after the telegram is made available for physical transmission as a value reads out the transmission time delay by which the time of the telegram entry is to be corrected.

Likewise, the actual reception time delay during transmission is advantageously taken into account if the second network subscriber has a second timer for determining the reception time delay, which he starts when a first telegram is received from a physical transmission link.

The runtime of the telegram over the physical transmission link between the first network subscriber and the second network subscriber can be the second as the starting value The timer must be saved before it starts. This has the advantage that the sum of the transit time and the delay in reception time can be determined by only one timer.

In a further development, the start and end of the runtime of a telegram can each be determined as the point in time at which a characteristic field of a telegram leaves a media-independent interface of the first network subscriber at a fixed distance from the start of the telegram or into a media-independent interface of the second network participant arrives. Advantageously, are measurements of the transmission time delay ^¬, duration and Empfangszeitverzogerung regardless of the length of the respective telegram.

If the network components meet the Ethernet, Fast Ethernet or Gigabit Ethernet specification, the type field can advantageously be used as the characteristic field of the telegram. In the second network participant, upon receipt of the type field, it is known that it is a telegram that is used for time synchronization, and the necessary mechanisms can be initiated. The data field is located behind the type field and can be changed in the sender until the type field is output to the media independence interface. This makes it possible to transmit the time corrected for the transmission time delay in the same telegram.

The runtime of a telegram over the physical transmission link can be exactly determined by the first network participant sending a first telegram to a second network participant for determining the runtime and starting a response time timer after the telegram has been provided for the physical transmission. After receiving the first telegram to determine the running time, the second network participant starts a timer to measure the time spent in the vehicle and stops the timer after providing a second telegram for physical transmission to the first Network participants. The measured residence tent is transmitted to the first network participant in the second telegram for determining the running time. After receiving the second telegram from the physical transmission, the first network participant stops the response time timer and calculates the duration of a telegram over the physical transmission path as half the difference between the measured response time and the residence tent in the second network participant.

A network subscriber, in particular a field device, can advantageously be equipped with a plurality of ports, in particular four ports, for connecting further network components. In this case, an interface, a so-called micro- processor interface, for connecting the ports to a subscriber-internal processor bus, and a control unit, a so-called ^¬ Switch control, are provided, which performs a Telegrammweglenkung between the ports and the microprocessor interface. This has the advantage that network participants, in particular field devices, m from the user of

Fieldbuses can be connected as usual in a line structure. A separate switch, as would be required with a star-shaped structure, is not required. In particular in the case of a network according to Ethernet, Fast Ethernet or Gigabit Ethernet specifications, the invention enables the construction of a network of large extent, since only the distance between two network components may not exceed certain limits, but the length of the line structure is unlimited , In addition, the integration of switch functions in the network participants has the advantage that the CSMA / CD access control can be deactivated, in particular in the case of Ethernet, and the network receives a deterministic behavior. The area of application of the network participants and the network is thus expanded to include application cases in which real-time behavior is required. If four ports are provided for connection of further network components on the network devices, may be part ^¬ participants are interconnected to form a two or three dimensional network structure, since at these two ports for the integration of the network station m a line two in each case to connect the line with another line can be used.

An embodiment of the interfaces implemented by the ports according to the Ethernet or Fast Ethernet specification has the advantage that, for example, a fieldbus with network components of this type can be made use of technology knowledge already available from other areas. In this way, a continuous network is obtained for the office, control, line and field levels, which enables transparent access to any data. A gateway for coupling network areas with different physics and different protocols is advantageously not required. In addition, networks based on the Ethernet specification are characterized by high data transmission performance. They offer cost advantages thanks to a widely available technology and components that are available in high numbers of pieces. It is possible to connect a large number of network participants to a network. The advantages of the preferred line or bus structure of the network, e.g. the advantage of simple interconnection of the participants, combined with the advantages of networks mentioned above based on the Ethernet specification according to IEEE 802.3. The switch functions integrated into the network participants assume the function of a previously separately installed network component, for example a switch, which is no longer required.

A further improvement in applications in automation technology, in particular in the use in time-critical applications, is achieved if the control unit of the Switch function is designed such that a transmission priority of the telegrams to be sent is evaluated and telegrams with high priority are sent before telegrams with low priority.

A microprocessor for correcting an internal clock using m telegrams of time information received has the advantage that the time synchronization can largely be implemented without additional hardware expenditure.

On the basis of the drawings, in which exemplary embodiments of the invention are shown, the invention and embodiments and advantages are explained in more detail below.

Show it:

1 shows a communication structure of an automation system, FIG. 2 shows a block diagram of an interface of a network participant, FIG. 3 shows a series connection of network participants with a linear network topology, FIG. 4 shows a series connection of network participants with two communication channels, FIG. 5 shows a two-dimensional connection of network participants,

Figure 6 shows a two-dimensional interconnection with redundant

Figure 7 shows a two-dimensional network after redundancy management, Figure 8 shows a three-dimensional network after redundancy management, Figure 9 shows the basic structure of a telegram and Figure 10 shows the structure of an order list.

FIG. 1 shows the structure of a communication structure in an automation system. Communication takes place continuously at the control, line and field level a network whose data transmission complies with the Fast Ethernet standard according to IEEE 802. u. At the field level there are a sensor 1, for example a pressure transducer, a sensor 2, here an ultrasonic flow transducer, an actuator 3, a control valve for setting a flow, and a programmable logic controller 4 with twisted-pair lines 5, 6 and 7 interconnected in bus form. The programmable logic controller 4 forms, together with the two sensors 1 and 2 and the actuator 3, a control loop, in which the position of the control valve m is predetermined as a function of the measured values of the pressure transducer and the flow transducer. The programmable logic controller 4 is connected to a switch 9 via a twisted pair line 8. A cell computer 10, a master computer 11 and a firewall 12, with which a secure Ethernet access is implemented, are also connected to the switch 9 in a star-shaped topology. With a line 13, further cell computers, not shown in the figure for the sake of clarity, from adjacent cells of the automation system are connected to the switch 9.

The example shown in FIG. 1 clearly shows the advantage of high data transparency across all levels. The same transmission standard is used for control, line and field level. The field devices 1, 2 and 3 are connected to the programmable logic controller 4 m in the manner customary in the user m of a linear topology. Another advantage is the consistent use of uniform addresses for the individual network participants. An address conversion, as would be required if different standards were used at the different levels, can be omitted in the new network and the new network participants in an automation system.

FIG. 2 shows the basic structure of the communication interface of a network participant, for example sensor 2 in FIG. 1. Application-specific circuit parts le, such as a supply mechanical-electrical transducer element, means for signal preprocessing, and a Spannungsver ^¬, of clarity, are not shown because. The parts combined in a rectangle 20 can be integrated in an ASIC (Application Specific Integrated Circuit). Communication with the application-specific circuit points of the network subscriber takes place via a microprocessor bus 21, to which a RAM 22, a microprocessor 23 and a microprocessor interface 25 are connected. Broken lines in the representation of the microprocessor 23 indicate that the integration into the ASIC is optional. Its functions could be taken over by an external processor. The task of the microprocessor 23 is the execution of user programs and communication functions, for example the handling of TCP / IP. Another task can be the management of send and receive lists of telegrams of different priority in the external RAM 22. The microprocessor 23 selects an order from a send list in the external RAM 22 and starts a DMA controller 26, which is referred to as DMA 1 control, via a microprocessor interface 25, after having previously assigned the number of times to the DMA controller 26 sending data bytes and a pointer that points to the data byte to be sent. Is the send order by the DMA controller 26 completely m one

Transmit buffer 27 transmitted, the microprocessor 23 removes this send job from the send list in the RAM 22 and processes the next send job, provided the send list is not empty and free memory space is still available in the transmit buffer 27.

Four Ethernet controllers 28, 29, 30 and 31 are also integrated in the ASIC 20. Each of these Ethernet controllers enters the data bytes of a completely received telegram via a multiplexer 32, a DMA controller 33, which is also referred to as DMA 2 control, and the microprocessor interface 25 m a receive list in RAM 22. The micro Processor 23 accesses the reception list and evaluates the received data in accordance with an application program.

The microprocessor interface 25 forms the essential

Interface between the Ethernet controllers 28 ... 31 and the microprocessor bus 21. It controls or arbitrates the write and read accesses that take place via the DMA controller 33 or the DMA controller 26 to the RAM 22. If there are DMA requests from both DMA controllers 26 and 33 at the same time, the microprocessor interface 25 decides on the access rights of the two DMA channels. Via the microprocessor interface 25, the microprocessor 23 can also write parameter registers 34 which are required for operating the communication interface of the network subscriber. Examples include a pomter on the start of the high-priority memory area in a transmit buffer of an Ethernet controller, a pointer on the start of the high-priority memory area in each of the receive buffers of the Ethernet controller, an operating mode register for general control bits, and an address of the series to which the network participant belongs, called a cycle time for so-called port select telegrams and settings for various monitoring time intervals.

The transmit buffer 27 has a size of more than three kilobytes and is divided into a memory area for high-pore and a memory area for low-priority telegrams. The ratio of the two memory areas can be parameterized. The memory areas of the transmit buffer for high and low priority data are each implemented as a ring buffer. Sending the data from the transmit buffer 27 via one or more Ethernet controllers 28 ... 31 begins when the number of bytes entered in a telegram is greater than the parameterizable fill level or when a complete telegram from the RAM 22 m the transmit buffer 27 pated and at least one Ethernet controller 28 ... 31 is free for transmission.

The Ethernet controllers 28 ... 31 are constructed identically. Their structure is explained in more detail using the example of the Ethernet controller. A device 40, which is referred to as Transmit Control, contains a control unit which is responsible for the transmission of telegrams, for repetitions, transmission abort etc. It forms the interface between the internal controller clock and the send clock. A transmit status register m of the device 40 is provided in each case for storing transmit status information for low-priority and high-priority telegrams. If a telegram was sent without errors via the port, a corresponding interrupt is generated.

A Media Independent Interface 41 (MII) integrates the MAC sublayer of Layer 2 according to the seven-layer model, i.e. of the data lmk layer. This forms an interface to a module 36 for physical data transmission.

The MII 41 also contains a transmit function block 42 and a receive function block 43. In addition, a MAC control block (not shown in FIG. 2), an address filter, a statistic payer and a host interface are integrated , Control and configuration data can be transmitted to the module 36 and status information can be read from it via the media-independent interface. The individual functions of the transmit function block 42 are: mapping of the bytes to be sent, detection of collisions in half-duplex operation and execution of a back-off algorithm, provision of transmit status information to the device 40 after termination of one Transmission process, compliance with the idle time inter-packet gap (IPG) between two telegrams, supplementing the transmission data with a preamble, a start-off-frame delimeter (SFD) and a parameterizable cyclic redundancy check word (CRC) , Filling a telegram with pad Bytes if the telegram length would be <60 bytes, and abort of a send operation on request.

The receive function block 43 makes the received bytes available to a device 44, which is referred to as receive control. The receive function block 43 recognizes the start-of-frame delimeter and a VLAN frame. He checks the Langenfeld and the CRC word in telegrams. After the reception process has ended, receive status information is made available to the device 44. Block 43 recognizes and removes preambles and start-of-frame delimeters in the case of telegrams. If the free memory space in a receive buffer 45 of the Ethernet controller 28 falls below a predetermined threshold in full duplex mode, the MAC control block sends a pause control telegram for flow control via the module 36. This telegram causes the connected network subscriber to send no data telegrams to the Ethernet controller 28 until the time interval sent with the pause control telegram has expired. The address filter carries out telegram filtering in accordance with unicast, multicast and broadcast addresses. To do this, the destination address (DA) received in a telegram is compared with filter addresses. The statistic payers store statistical information about sending and receiving operations. The host interface allows access to parameter registers and statistics payer of the Ethernet controller 28 by the neighboring network participants.

The device 44 contains a control unit which is responsible for receiving telegrams. It forms the interface between the internal clock of the Ethernet controller 28 and the receive clock.

The receive buffer 45 has a size of more than 3 kilobytes. It is divided into a memory area for high priority and m a memory area for low priority telegrams. The The ratio of the two memory areas can be parameterized. The memory areas are each implemented as a ring buffer.

The DMA controller 33 controls the DMA transfer from one of the receive buffers m the Ethernet controllers 28 ... 31 to the RAM 22. The DMA transfer begins when m of the receive buffers, for example in the receive Buffer 45, the number of data bytes received has reached a parameterizable minimum fill level or a telegram has been completely received. At the same time, this receive buffer must be selected for the DMA transfer by a module 46, which is referred to as switch control.

A multiplexer 47 is connected upstream of the device 40, which is controlled by a control unit 46, which is referred to as switch control.

Switch-Control 46 controls the forwarding of data between the Ethernet controllers 28 ... 31 and the storage of received data if they are intended for the respective network participant. Since the application of the invention is not limited to networks according to the Ethernet specification, the Ethernet controllers 28 ... 31 are also generally referred to below as port 1, port 2, port 3 or port 4. Which ports are released for the forwarding of received data depends on the network structure m the participant is involved in. Switch-Control 46 controls the following actions as a function of the operating state, the network structure, the received destination address and the telegram pπoπtat:

If the received destination address is the same as the subscriber's own address, the received telegram is transmitted via the microprocessor interface 25 m to the RAM 22 without forwarding it to other ports. - If a broadcast telegram is received at a port, the telegram m is transferred to the RAM 22 and the other released ports for sending.

If a telegram with a multicast address that corresponds to one of the multicast addresses stored in a filter table 48 is received at a port, the telegram is transferred to the RAM 22 and made available to the other released ports for transmission. If the received destination address is different from the own subscriber address and the multicast addresses, the telegram is made available to the other released ports for sending without being saved for further processing.

Eight priority levels are available for telegrams with so-called VLAN bytes, for example. If several telegrams are waiting to be sent, the transmission order of the telegrams is determined according to their transmission priority.

In a monitor mode operating state, all telegrams which meet the parameterized filter conditions are transmitted to the RAM 22.

Telegram forwarding taking into account a modified spanning tree algorithm.

Switch-Control 46 contains other parameters, the meanings of which will be explained in more detail later: One

Row address R _P3 , which corresponds to the row connected to port 3, a row address Rp ₄ , which represents the address of the row connected to port 4, a number N _{Ri of} the transmission links to port 1, a number N _{R2 of} the transmission links to port 3 , a value | N _RI - N _R2 1 _{s of} the respective network participant, a value | N _Ri - N _R2 1 S _forming the sender of a received port select telegram, an amount [N _R1 - N _R2 1 min as the lowest previously received value, a source address A _Se Direction of a received message, a source address A _st0 red of the telegram with the smallest value of Amount N _Ri - N _R2 | _min , best received combination (Root ID.Cost .Transmitter ID. Port ID) _P3 for port 3, one best combination received

(Root_ID.Cost .Transmιtter_ID.Port_ID) P4 for port 4, a best received combination (Root_ID. Cost. Transmιtter_ID. Post_ID) _{R of} the series, a message interval counter for a cycle time of port select telegrams, a timeout Payer for a timeout interval on port 1, a timeout payer for a timeout interval on port 2, a timeout payer for a timeout interval on port 3, an active time payer for a time interval beginning with the last one Receipt of a port select telegram on port 4 begins, a combination aging counter for a maximum time interval within which a configuration telegram must be received, otherwise the stored combination Root_ID. Cost. Transmιtter_IC. Port_ID is deleted, a payer for a time interval

after which a port 3 of a series switches from inactive to active, which corresponds to twice the worst case throughput time of a port select telegram through the series, and a payer for a time interval Δt _ne rdeiay / after which a port from potentially active to is actively switched and which corresponds to twice the worst case throughput time of a configuration telegram through the network.

The user can enter multicast and virtual LAN identification addresses, so-called VLAN addresses, in the filter table 48. A multicast or VLAN

Telegram is only accepted if the received address matches one of the addresses m of the filter table 48.

A device 50 for redundancy control is intended to ensure in a network that detected physical errors do not impair communication between the network components. Firstly, there is redundancy within each row formed with network participants. To do this, the network participants connected in series must form a ring that is open at one point in the event of a fault, in the

However, an error can be closed. Secondly, there is redundancy with several communication channels between the Rows possible. To do this, a number of network participants must be connected to an adjacent row via at least two port ₃ . There is always only one communication channel active between two rows, ie data telegrams are only exchanged via this communication path. If an active communication channel between two rows is identified as faulty, it is deactivated and switched to another communication channel. To implement the redundancy, the device 50 includes a cycle time register with a parameterized cycle time for test telegrams, a cycle time counter for generating a cycle time interval, a control unit for switching over to a redundant communication channel and for initiating the sending of so-called Lmk Up or link-down telegrams, a row runtime register with a parameterized worst case throughput time of a telegram through a row and a row runtime counter used to generate a row runtime.

Certain events are communicated to the microprocessor 23 via a device 51 for interrupt control, which is also referred to as interrupt control. These are essentially messages from telegrams sent or received and error messages. The device 51 contains an interrupt request register, an interrupt mask register, an interrupt register and an interrupt acknowledge register. Every event is stored in the interrupt request register. Individual events can be suppressed via the interrupt mask register. Only the events from the

Interrupt mask registers cannot be masked. The entry m the interrupt request register, however, is independent of the interrupt mask in the interrupt mask register. Bits in the interrupt request register can be reset with write access to the interrupt acknowledge register.

A module 52 contains special user functions that m the communication interface of the network participant are integrate. A partial function is implemented with a module 53 for time synchronization, another with a module 54 for aquidistance, which will be explained in more detail later. A delay timer 1 to 4 with the reference numerals 57, 58, 59 and 60 is provided for ports 1 to 4, which determines the transmission time between the respective network subscriber and the network subscriber connected via the respective port. The respective delay timer is also used as a lead time timer (DLZ timer) for the respective port. There are also one for each port

Aquidistance timer, an auxiliary timer for a transmission time .DELTA.t _x via the respective port and a parameter .DELTA.t _{DLjZ are} provided, which _{corresponds to} the sum of the throughput times in the send and receive _direction and the cable _runtime between the communication interface and the network _subscriber connected via the respective port , There is also a local clock 37 m from the network subscriber, the time of which can be read and set via the microprocessor bus 21.

An integrated serial-peripheral interface (SPI) 55 is a simple but powerful serial bus system for connecting peripheral components, e.g. EEPROMs. An integrated I / O interface 56 is a parallel interface with 12 configurable inputs and outputs. About these

Interface can be used to control LEDs for status display, for example.

Each port of the communication interface can be parameterized operated in half-duplex or in full-duplex mode. While half-duplex mode is set on one port, full-duplex mode can be parameterized on another port at the same time. In full duplex mode, telegrams can be sent and received at the same time. This is not possible in half-duplex mode.

An application-specific application program, which can be stored, for example, on the RAM 22, contributes sending data m an order list in RAM 22. The DMA controller 26 copies data from this job list into the transmit buffer 27. Compiled telegrams are passed on to the released Ethernet controllers 28 ... 31. If a transmission conflict occurs because other telegrams are currently being routed through the communication interface, controlled by switch control 46, the transmit buffer 27 should be able to store two complete Ethernet telegrams. The transmission of the data from the transmit buffer 27 begins when a number of data bytes to be parameterized or a complete telegram from the RAM 22 m has been transmitted to the transmit buffer 27 and at least one Ethernet controller is free. The telegram remains stored in the transmit buffer 27 until it has been sent via all released Ethernet controllers 28 ... 31. The number of data bytes of a telegram, which must at least be stored in the transmit buffer 27 before being sent, must be parameterized in such a way that a seamless transmission of the telegram is guaranteed. Otherwise the telegram will be received incorrectly by other network participants. If telegrams of different priorities are stored in the transmit buffer, the telegrams are sent in accordance with their transmission priority.

Figure 3 shows an example of an interconnection of three

Network participants 61, 62 and 63 m linear structure. For a better clarity of the representation, the ports 1 to 4 of the communication interface of the network participants 61, 62 and 63 m are subdivided into circuit locations T1 to T4 for the transmission direction and circuit parts R1 to R4 for the reception direction. For example, port 2 can also be referred to as port T2 / R2. For a linear structure, in the manner shown, port T2 / R2 of the network subscriber 61 with port T1 / R1 of the network subscriber 62 and port T2 / R2 of the network subscriber 62 with port T1 / R1 of the

Network participant 63 connected. Data is transferred using a twisted pair cable for each transmission tragungsrichtung. The ports involved can thus be operated in full duplex mode. End devices can optionally be connected to the open ports T3 / R3 and T4 / R4 in FIG. 3 and to the port T1 / R1 of the network subscriber 61 or the port T2 / R2 of the network subscriber 63 and thus coupled to the network.

FIG. 4 shows a number of network participants 70, 71, 72 and 73, each of which can exchange some data via two communication channels. The communication channels are each realized by connecting the port T2 / R2 to the port T1 / R1 of the adjacent network subscriber and the port T4 / R4 to the port T3 / R3 of the adjacent network subscriber m in the manner shown. For example, a high-pore and a low-pore communication channel can be set up and the data throughput doubled. There is no data exchange between the communication channels, i.e. a telegram received at the switching point R1 can - if necessary - only be forwarded by the switching part T2. Both communication channels are operated in full duplex mode.

FIG. 5 shows an example of a two-dimensional interconnection of the network subscribers. Network subscribers 80, 81 and 82 are interconnected in a row in the manner already described with reference to FIG. In addition, network participants 83, 84 and 85 form a series and network participants 86, 87 and 88 form a series. 7Terminals 89, 90 and 91 are connected to ports T4 / R4 of network participants 80, 81 and 84, and terminals 92, 93 and 94 are connected to ports T3 / R3 of network participants 83, 84 and 87. By connecting the Ports T4 / R4 of network participant 82 with port T3 / R3 of network participant 85 provide a communication channel between the respective rows. Correspondingly, two communication channels are formed between the network participants 83 and 86 and between the network participants 85 and 88. So that loop freedom in Network is, however, allowed to be activated only one commu ^¬ nikationskanal at a time from them.

The rows formed from the participants 80 to 82, 83 to 85 and 86 to 88 are each assigned a unique row address R], which is stored in a parameter register “row address *”.

A further two-dimensional network is shown in FIG. 6 to clarify the redundancy control. 8 each

Network nodes 100 ... 107, 110 ... 117, 120 ... 127 and 130 ... 137 are connected in a row. Both the broken lines and the solid lines between the network participants represent communication channels. However, it must be ensured that only one communication path is used between any two network participants in the entire network. Loops would occur with several possible communication paths, ie telegrams would multiply and circulate. The Spannmg-Tree algorithm has been developed to avoid such situations. Data telegrams are only received by ports, forwarded to ports and sent by ports that are contained in the voltage tree. The remaining ports are deactivated. Deactivated communication channels are shown with broken lines in FIG. 6, activated with solid lines. For redundancy within a row, the two line ends are connected to one another, for example at network participants 100 and 107. In the case of an error, the communication channel created in this way is deactivated, and in the case of an error m the active state is set. This redundancy requires an uninterrupted line structure. Since the spanning tree algorithm may have also interrupted a connection via the ports T1 / R1 and T2 / R2, it cannot be used unchanged. In the following a method is presented that is used for a network of interconnected rows of network participants Ensures loop freedom without having to break a row. If necessary, only ports T3 / R3 are deactivated. Only one communication channel may be active between two rows at a time, ie data telegrams are exchanged via this communication path. There is no data exchange via the other communication paths between two rows. The selection of the only active communication channel between two rows takes place with the help of port select telegrams. These are telegrams that are only forwarded within a row. There is no exchange between the rows.

The task of these port select telegrams is to find a network participant that is connected to an adjacent row via port T3 / R3 and is as far away from both ends of the line structure as possible based on the number of network participants, i.e. has the smallest distance from the center of the row. These properties define the only network participant in the series that is actively connected to an adjacent series via port T3 / R3. All other connections via ports T3 / R3 from network participants of the same row to this neighboring row are deactivated. No data telegrams are exchanged via deactivated communication channels.

Port select telegrams are clearly identified by an identifier in the type field.

FIG. 7 shows the result of the redundancy control in a two-dimensional network in a different type of representation. The number entered in the individual boxes corresponds to the respective address of the network participant. Port Tl / Rl is on the left, port T2 / R2 on the right, port T3 / R3 on the top and port T4 / R4 on the bottom of the network participants. With two solid parallel lines between two participants, there is an active one, operated in full duplex mode Communication channel shown. The machines with two through broche ^¬ lines drawn communication channels are deactivated.

The data area of port select telegrams that are received by a network participant via port T2 / R2 contains information about the number N _{R of} the transmission links between port Tl / Rl of the network participant on the “right” edge of the row and the port T2 / R2 of the respective network subscriber and contains the number N _{Ri of} the subscriber who was the last to forward or send the received port select telegram.

The data area of port select telegrams that are received via port T1 / R1 contains the number N _r of transmission links between port T2 / R2 of the network participant at the "left * edge of the row and the port T1 / R1 of the respective network participant as well the number N _R that is valid for the network participant that was the last to forward or send the received port select telegram.

Regardless of the port via which a port select telegram was received, it contains the value IN _R] - N _{R Inιt} - _latoI at the initiator of the received port select telegram, the 16 bit address R _t (0 <k <p, p number of rows) of the row to which the initiator of the port select telegram belongs, and a valid bit V for the received value of | N _R1 - N _R limt-iator and for the row address R _k . V = 0 means that the received values are invalid. Such a port select telegram was sent by a network participant

Row fed, which is not connected to its neighboring row via a ready port T3 / R3. If V = 1, the received values are valid. The port select telegram was fed in by the network subscriber m the row, which is connected to an adjacent row via an operational port T3 / R3. A connection to the neighboring row is ready for operation if within a parameterizable time interval Δtt- _ιmeθ u- (timeout interval) a port select telegram is received at port P3 / R3. This is only possible if the port T3 / R3 of the network subscriber in its own row and the port T4 / R4 of the network subscriber in the adjacent row are each in an “lmk-pass *” state. In this state, telegrams can be transmitted in both directions.

In the steady state, only the network participant in each row sends cyclically, ie m every reporting interval Δt _M , port select telegrams, which is the only one actively connected to the next row via port T3 / R3. This shows whether this connection between two rows is still active. A method is described below according to which this network participant can be determined:

1. Network participants also send port select telegrams to be forwarded or compiled themselves via their port T3 / R3.

2. Upon receipt of a port select telegram via port T3 / R3, each network participant recognizes whether it is connected to another row via this port. Network participants set the valid bit V to one if a port select telegram has been received via port T3 / R3.

3. Port select telegrams received on port T3 / R3 are sent back to the sender unchanged. The network participant previously saves the address R _n received with the port select telegram of the row connected via port T3 / R3.

4. A timeout counter is assigned to port T3 / R3, which is incremented with an adjustable clock. Each one

Port T3 / R3 received port select telegram resets this payer. The network participant sets the valid bit V to zero when lrnerhalb a parametπerbaren timeout interval Δtt-m _eo - is gen no port select message are received, ^¬.

5. Network participants also send port select telegrams to be forwarded or compiled themselves via port T4 / R4.

6. When a port select telegram is received via port T4 / R4, a network participant recognizes that it is connected to another row via this port.

7. Port select telegrams received on port T4 / R4 are sent back to the sender unchanged. The network participant previously saves the address R _r received with the port select telegram of the row connected via port T4 / R4.

8.Network participants send their own, i.e. self-made, port select telegrams

8.1. via port T1 / R1 with N _R2 = 1 and port T2 / R2 with N _R1 = 1 during initialization with amount IN _R1 - N _R _. Iι, nt _la r _r = FFH and valid bit V = 1 if a port select telegram has already been received via port T3 / R3, or valid bit V = 0 if no port select telegram has been received via port T3 / R3 was received. 8.2 via Tl / Rl with N _R2 = 1 and port T2 / R2 with (N _Ri + l) if no port select telegram or data telegram was received within a parameterizable time interval Δtt-imeoj- at port T2 / R2. A timeout counter is assigned to port T2 / R2, which is incremented with an adjustable clock. Each port select telegram or data telegram received on port T2 / R2 resets this payer. 8.3 via port Tl / Rl with (N _R2e m _F f + 1) and port T2 / R2 with (N _R ι + 1), if a port select telegram is received at port T2 / R2 with the received value not equal to the stored value of N _R2 . In addition, N _R2e mpf is stored.

8.4 via port T2 / R2 with (N _R1 +1), if a port select telegram is received at port T2 / R2 with N _{R1 load} sender not equal (N _Ri + l).

8.5 via port T2 / R2 with N _Ri = 1 and port Tl / Rl with (N _R2 +1), if no port select telegram or data telegram was received within a parameterizable time interval Δti _meout at port Tl / Rl. A timeout counter is assigned to the port T1 / R1, which is incremented with an adjustable clock. Each port select or data telegram received at port Tl / Rl resets this counter.

8.6 via port T2 / R2 with (N _Rlemp f + l) and port Tl / Rl with (N _R 2 + 1) if a port select telegram is received at port Tl / Rl with a received value N _R ι _emp f not equal to the stored value of N _R1 . In addition, N _R iempf is stored.

8.7 via port Tl / Rl with (N _R +1) if a port select telegram is received at Port Tl / Rl with N _R i _aGt s _e rιd ι not equal (N _R2 +1).

9. Network participants that are ready for operation

Communication channel are connected to another row via port T3 / R3 and receive a port select telegram with a valid bit V set to one, compare IN _RI - N _R2 limtiaor of the received port select telegram with amount | N _R ι - N _R | _s of one's own station: 9.1 Is | N _R I - N _R itiat r <I _R1 - N _R2 | N _R2 lim iaor in * data field of the port select Tele ^¬ program not changed when forwarding - N _RI | _3, it is. The network participant saves

INRI - N _R2 Imm = I NRI - N _R limtiator and sets the address stored = A _Inιtιat or. A _IriltI3tor is the source address of the received port select telegram. The value

[N _RI - N _R is the distance of the receiving station from the center of the row. 9. 2 I st | N _R1 - N _R2 li _m tiato _r = IN _Ri - N _R2 , Aimtiator is compared with its own station address A _s :

With Aimtiator <A _s , the port select telegram is forwarded with IN _Ri - N _R2 limtiator without changing the data field. The network participant saves

I NRI - N _R 2 Imin ⁼ I NRI - N _R2 Is And A _s t_ored ⁼ Aimti ator.

If Aimtiator = A _Ξ , the received port select telegram is filtered out, since this case is only possible in the event of an error. If Amtiator> A _s , the received port select

Filtered out telegram and a separate port select telegram with | N _R ι - N _R2 limtiator set to | N _R1 - N _R I _{S sent} via the ports T1 / R1 and T2 / R2. The network participant stores I NRI - R l _{ml n} = IN _R1 - N _R2 Is, and A _s to red = _s .

9.3 If | NRI - N _R2 limtiator> IN _Ri - N _R2 , the received port select telegram is filtered and a separate port select telegram with IN _Rα - N _R2 limtiator is set to IN _R1 - N _R2 | _{s sent} via the ports T1 / R1 and T2 / R2. The network participant saves

I NRI - N _R2 l _mln = I NRI - N _R2 Is And Astored = A _s .

10. Network participants that are not connected or connected to another row via a non-operational communication channel via port T3 / R3 and receive a port select telegram with a valid bit V = 1 route the telegram with the received valid bit V and the value IN _RI - N _R2 limtiator within the series. The network participant stores I RI - NR ₂ Imm = | NRI - N _R2 limti ato r und A _st ored ⁼ Aim ti ator -

11. Network participants that receive a port select telegram with a valid bit V = 0 forward the telegram with V = 0 and the value IN _Ri - N _R2 limtiator within the row. The stored values of | N _Ri - N _R2 | _mιn and A _{Ξt = red} remain unchanged. 12. An operational port T3 / R3 is activated when | N _Ri - N _R2 Lm = IN _R1 - N _R l _s and A _st0 red = A _{s is} saved. This applies for a period of time Δt _rθ wdeiay which corresponds to at least twice the worst case throughput time of a port select telegram through a series.

13. An active port T3 / R3 of a network participant is deactivated if the network participant does not receive a port select telegram from another row within the timeout interval Δt _t i _m eout. In addition, the Kommu ^¬ nikationskanal through the port T3 / R3 is in the other row as not operational.

An active port T3 / R3 is also deactivated when the network participant receives a port select telegram with | NRI - N _R2 limtiator <IN _Ri - N _RS or

IN _I - N _R2 limtiator = IN _Ri - N _RS and activator <A _s . This network participant stores the received values IN _RI - N _R2 limtiaor and Aι _nιt ιator and forwards the received telegram. The communication channel via port T3 / R3 to the other row remains operational.

14. Network nodes that are connected to another row via an operational communication channel via port T3 / R3 send their own port select telegrams cyclically in each message interval Δt _M.

14.1 via the port Tl / Rl with (N _Ri + l) and the port T2 / R2

(N _RI +1), if an active port T3 / R3 is deactivated, with IN _Ri - N _R2 limtiaor = FFH and valid bit V = 1 until a port select telegram from another network participant is received;

14.2 via port Tl / Rl with (N _R2 +1) and port T2 / R2 with (N _RI +1), if within a parameterizable time interval Δt _tlme -ut neither at port Tl / Rl nor at port T2 / R2 Port select telegram or data telegram from the network participant with the only active communication channel to the neighboring one Row was received, ie a telegram with the source address A ored 14.3 via the port Tl / Rl with (N _R , + 1) and the port T2 / R2 with (N _RI +1) if | N _RI - N _R2 | _mn = IN _Ri - N _R2 | _s and A _s t _or ed = A _{s is} saved.

In the steady state of the method, each network subscriber in the row knows the network subscriber who is connected to an adjacent row via his port T3 / R3 and has the smallest distance from the row center. Data telegrams are only exchanged between the two rows via this active communication channel. The connections of the other network participants to the next row are deactivated. FIG. 7 shows a network in this steady state.

If, in deviation from this exemplary embodiment, the only active communication channel of a row to the adjacent row is to be on the edge of the row, then in the described method I NRI - NR ^ lin by | NO! - _R 2 LI NRI - N _R imt ιator <I NRI - N _R2 L with | NRI - N _R , limtiator> IN _R1 - N _R __.

FIG. 8 shows a network with a three-dimensional structure. The arrangement of the ports on the individual boxes, which each represent a network participant with the entered address, is the same as in the illustration in FIG. 7. The communication channels are also shown in the same way. In the case of a three-dimensional structure, a series m of linear structure is built up with several network participants by connecting the ports T1 / R1 and T2 / R2. Several of these rows are interconnected to form a three-dimensional structure, as shown in FIG. 8. To do this, there must be at least one communication channel between ports T3 / R3 and T4 / R4 between every two rows. Multiple communication paths between two rows are permitted. At the ports T3 / R3 and T4 / R4 of the network participants that are not for communication channels terminal devices can be connected between rows. Each row is assigned a unique row address Ry with 0 <k <p, where p is the number of rows in the selected network structure. The respective row addresses are shown on the left side of FIG. 8 next to the respective row. The associated address of the row is stored in the parameter register "Row address *" in each network node. However, it must be ensured that only one communication path is used between any two network participants in the entire network. Loops occurred on several communication paths, ie telegrams could multiply and circulate. To avoid loops, port select telegrams are used in combination with a modified Spanmng tree algorithm.

For this purpose, the data area of the port select telegrams is expanded by the address R _{n of} the adjacent row to which the port T3 / R3 or the port T4 / R4 of the network subscriber who compiled the telegram is connected.

The task of the port select telegrams expanded by the row address R _{r of} the adjacent row is to find a network subscriber which is connected to a row with the address R via port T3 / R3 and in relation to the number of

Network subscriber is as far as possible from both ends of its row, ie has the smallest distance from the middle of the row. This defines the only network participant in the row that is potentially actively connected to the adjacent row with the address R _r via port T3 / R3. Port T3 / R3 is switched from potentially active to active if the modified Spanmng tree algorithm also switches this port active. Data telegrams are only exchanged via active communication channels between the rows. With the method previously described for the two-dimensional network structure, it is possible to find the network subscriber who has the smallest distance from the center of the row and whose port T3 / R3 is connected to the row with the address R _N. The port select telegrams ensure that between two rows that are directly connected to each other via communication channels, only one communication channel is potentially active at any time via port T3 / R3. In order to reliably prevent loops that are closed over more than two rows, a modified tension tree method ensures that no loop occurs across the entire three-dimensional network. Characteristics of the modified voltage tree method are that each row is regarded as a virtual switch, with the potentially active communication channels via ports T3 / R3 or via ports T4 / R4 to other rows as ports of the virtual switch and that a communication channel via a port T4 / R4 is potentially active if it is connected to a potentially active port T3 / R3 of another row, which is also regarded as a virtual switch. In addition, the following entries are provided in the data field for configuration telegrams: 1. Root_ID: A 64 bit address R _{R of} the virtual switch, which is assumed to be “Root ^w ”.

2. Transmιtter_ID: A 64 bit address R _{τ of} the virtual switch to which the sending network participant belongs. The addresses R _κ and R _τ each correspond to the address of the row that is regarded as a virtual switch.

3. Cost: Smallest number of rows that a telegram from a sender to the Root_ID must go through.

4. Port_ID: A 16 bit address P _{ID of} the port via which the sending virtual switch sends the configuration telegram. R _F ID is equal to the address R _{n of} the row that is connected to the port via which the virtual switch sends with the Transmιtter_ID.

With these definitions, the Spannmg-Tree algorithm can be applied to a network of virtual switches. It is based on the described configuration telegrams that are sent and received by virtual switches. Only the potentially active or active ports T3 / R3 or T4 / R4 of a row, ie a virtual switch, evaluate received configuration telegrams. The deactivated ports T3 / R3 or T4 / R4 evaluate the configuration telegrams and then filter them. The voltage tree method switches the ports T3 / R3 or T4 / R4 from potentially active to active, which ensure that there is only one communication path between any two network participants in the network and therefore no loops occur. The remaining ports T3 / R3 or T4 / R4 remain potentially active or deactivated. Data telegrams are only exchanged via active communication channels between the rows.

A virtual switch is constantly on at its ports for

Configuration telegrams ready to receive and save the configuration message for each port with the "best * combination of Root_ID. Cost. Transmιtter_ID. Port_ID. Not only are the received combinations compared for each port, but also the combination that the virtual switch has sent to this port is compared. A combination Kl is "better * than another combination K2 if 1. Root_ID of Kl <Root_ID of K2, 2. Root_ID of Kl = Root_ID of K2 and Cost of Kl <Cost of K2, 3. Root_ID of Kl = Root_ID of K2 and Cost of Kl = Cost of K2 and

Transmιtter__ID of Kl <Transmιtter_ID of K2 or 4. Root_ID of Kl = Root_ID of K2 and Cost of Kl = Cost of K2 and

Transmιtter_ID of Kl = Transmιtter_ID of K2 and Port_ID of Kl <Port_ID of K2.

The root port of a virtual switch is the port with the "best * received combination K _R = K _L = Root ID.Cost.Transmitter ID. Port ID. The root port is the port of a virtual switch with the shortest distance to the Rooc_ID.

The combination of the root port is communicated to all network participants of the virtual switch via port select telegrams. This means that every network participant has the necessary information to decide whether an em port should be switched from potentially active to active. A potentially active port is switched to active if Root_ID. (Cost + 1) .Transmιtter_ID.Port_ID from the root port

"Better * is than Root_ID. Cost. Transmιtter_ID. Port_ID of the considered port.

The condition that leads to the activation of a port of a virtual switch must be valid for a period of time Δt _nc , t _d eia _y which corresponds to at least twice the worst case throughput time of a configuration telegram through the network before the relevant port is actually activated , Only configuration telegrams received from the root port are forwarded to the active ports of the virtual switch. Configuration telegrams are only sent or forwarded via the active ports T3 / R3. The only receivers of these telegrams are the potentially active ports T4 / R4 of the connected virtual switches. In addition, configuration telegrams are only sent or forwarded via the active ports T4 / R4. The only receivers of such telegrams are the potentially active ports T3 / R3 of the connected virtual switches. A so-called combination aging payer is assigned to each port of a virtual switch. This

The payer is reset and restarted with every received or forwarded configuration telegram. The combination aging counter is therefore only activated for the potentially active or active ports in a row and is incremented with a parameterizable time cycle. If the combination aging counter reaches the parameterizable threshold value for a potentially active or an active port "Maximum age *, the combination Root_ID saved for this port becomes. Cost. Transmιtter_ID. Port_ID deleted and recalculated.

The exchange of information within a virtual

Switches, that is to say within a number of network participants with a linear structure, are carried out using port select telegrams which are similar to the above described port select telegrams of a network with a two-dimensional structure. The data area of the port select telegrams of a network with a three-dimensional structure is expanded independently of the receiving port compared to the data area of the port select telegrams for a network with a two-dimensional structure by a 16 bit address R _{r of} the one connected via port T3 / R3 virtual switches, ie the neighboring ones

Row whose validity is indicated by the valid bit V already described. If V = 0, the received value of row address R _{r is also} invalid. The port select telegram was fed into the virtual switch by a network participant, which is connected to the virtual switch via an operational port T4 / R4. If V = 1, the address R _{n is} valid. In addition, a potentially active bit P _L is added to the data area of the port select telegram. Depending on the receiving port, this bit has two meanings:

_{1.P pA} m port select telegrams received at port T4 / R4 informs the network _subscriber whether port T3 / R3 of the sending network _{subscriber of} the connected virtual switch is potentially active or active (P _pΛ = 1) or deactivated ( P _p = 0).

2. Pp ^ m port select telegrams that were received at port Tl / Rl or port T2 / R2 informs the network subscriber whether port T4 / R4 of the initiator of the port select telegram is potentially active or active (P _c . = 1) or deactivated (P _pP = 0). Furthermore, the data area of the port select telegram is expanded by a 16 bit address R _{x of} the virtual switch connected via port T4 / R4. The value of the address is only necessary if P _pA = 1 is set.

In addition, the value of an active timer is transmitted in the port select telegrams at the time of transmission. The active timer measures the time that has elapsed since the last receipt of a port select telegram via port T4 / R4 with the potential active bit set, ie with P _pA = 1. The value of the active timer is only valid if P _DP = 1.

Furthermore, the data area of port select telegrams for three-dimensional network structure contains the best received combination for this port

K _E = Root_ID.Cost .Transmιtter_ID. Port_ID that was sent or forwarded in the data field of a configuration telegram from a row connected to a potentially active or active port T3 / R3 or T4 / R4 with the address R _n or Ri.

In addition, the best known combination to date is at the potentially active or active ports T3 / R3 and T4 / R4 of the series, i.e. of the virtual switch, transmitted in the data field of port select telegrams:

K _R = Root_ID.Cost .Transmιtter_ID.Port_ID.

A network participant that on a deactivated port T4 / R4 em port select telegram from a potentially active or active port T3 / R3, i.e. em port select telegram with

P _PA = 1, another row receives, switches the port T4 / R4 to potentially active or active and sends a parameterizable number of port select telegrams with P _pA = 1.

The ports T4 / R4 are each assigned an active timer, which is incremented with an adjustable clock. The active timer measures the time since the last reception of a port Select telegram with the potential active bit P _Ό? = 1. Each port select telegram received via port T4 / R4 with the set potential active bit P _pA = 1 resets the active timer and restarts it. Received port select telegrams with P _PA = 0 reset the active timer without starting it.

A network participant with a potentially active or active port T4 / R4 deactivates this port if 1. a port select telegram with P _pA = 0 is received via port T4 / R4,

2. via port T1 / Rl or T2 / R2 a port select telegram is received with P _pA = 1 and a received value of the active timer that is less than the own active time, the own active timer in this case reset without restarting, or

3. the time measured by the active timer reaches a parameterizable maximum value.

In the steady state send m every virtual

Switch, ie in each row, all network participants with a potentially active T3 / R3 connection to an adjacent row connected via ports T3 / R3 cyclically every reporting interval Δt _κ each with a port select telegram via ports Tl / Rl and T2 / R2.

In addition, the following network participants send each port in a virtual select switch via the ports T1 / R1 and T2 / R2: 1. Each network participant during initialization with K _R = K _E = source address. 0. Source address. Port_ID,

2. each network participant with a potentially active communication channel via the port T3 / R3 to a row with the address R _n when it receives a configuration telegram via port T3 / R3,

3. each network participant with a potentially active communication channel via port T4 / R4 to a row with the address R _x , whom he receives a configuration telegram via port T4 / R4,

4. Each network participant at which the combination aging payer of a potentially active or active port reaches the threshold value “maximum age *, the combinations K _E and K _R stored for this port being deleted and recalculated, and first of all e port select Telegram with

K _R = K _E = source address .0. Source address. Port_ID is sent

5. each network participant with a potentially active or active port whose stored combination K _{R is} “better * than the combination K _R in the received port select telegram, the combination K _R stored for this port being deleted and recalculated, and wherein e Port select telegram with the best combination received so far for this port

K _E = Root_ID.Cost .Transmιtter_ID. Port_ID and with K _R = mm {K _E , received value from K _R } is sent and 6. Each network participant, whose port T4 / R4 is switched from deactivated to potentially active or active, sends a parameterizable number of port select telegrams with P _pA = 1.

All receivers of a port select telegram with a deactivated communication channel to another row store the values K _E and K _R sent by the associated potentially active or active port of the virtual switch.

FIG. 8 shows the result of using the port select telegrams in combination with the modified voltage tree method on each row of the three-dimensional network shown.

Redundancy in the network is intended to ensure that physical errors, electromagnetic interference, network expansions or component replacement ensure communication between the network components. The prerequisite for this is not only rapid detection of errors or network modifications and quick network reconfiguration, but also a network area that is as small as possible, which is affected by the effects of the error or network modification during the reconfiguration time.

The redundancy of a redundancy management is a network within each row, the posted communication ^¬ ducts interconnected between each two rows and redundancy with respect to the entire network possible. The modified Spannmg-Tree algorithm guarantees freedom from loops.

This type of redundancy advantageously enables short reconfiguration times with minimal hardware expenditure and can therefore be implemented with little effort. In addition, the network area is limited which is affected by the effects of an error or a network configuration during the reconfiguration time.

In order to ensure redundancy in a series of network subscribers connected in the form of a line, a ring is formed, as is the case in FIG. 6 with the network subscribers, for example

100 ... 107 is the case. A network subscriber, for example network subscriber 100, which is located at one end of the row, must be operated in redundancy mode. It acts as a redundancy manager.

By setting a redundancy bit in the parameter register, this network participant is switched to the redundancy mode. To check the series, it cyclically sends a Testl telegram to port 1 with the MAC address of port 1 as the source address. The cycle time is, for example, 10 ms. Test 2 is sent cyclically on port 2 with the MAC address of port 2 as the source address. The cycle time is cυ ⁾ > M - * t- ¹

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0 ≥; φ Φ li 3 i-. CΛ φ ≤ 3 H 1 Φ h- ^* M Φ li Φ Ό Φ rt φ CΛ I- ¹ CΛ

3 Φ o 3 d rl- J s: r + T) HNJ α HH li d li ι-i α H Φ? Ö Φ I— ¹

H rt Φ er φ tr CΛ Φ Φ N o H α d 3 o d Φ z tr H O H tr Φ υ3 φ rt o

? N Φ ι-j Φ Φ Φ α H s: H Φ 3 ιQ s: CΛ φ 1— 'Φ od ö φ OJ ι- (1 ι-i HN tu s rt £ h H ¹ c CΛ r + H Φ ι- 3 H Φ H- tr J σ I- ^* OJ tr rt rt φ Φ Φ φ CΛ P Φ H CΛ 3 d <Φ <rt HH rt φ rt Φ tr ^ Φ φ

HH 3 HHH o C α? Φ α OJ CΛ O Φ rt- H φ d Φ d O I- ^* Eg <«^

O Ϊ O 3 Φ P t 3 JI— ¹ rt HJP o ≤ <r + d ι-i Φ Φ rt φ d α Φ φ d Φ

3 rt H. tr Φ φ HP - Φ CΛ .V rt t H o rϊ- ^• *> rt tr Φ d rt £ Φ 3 tQ H ι-i ö

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H 3 Φ d 3 N) 1 h- ^* H h rt α 1— 'Φ ≤ Φ d> -3 - ^■ li d OJ φ tr Φ ω

OJ 1— ^■ ιQ CΛ Φ s: φ rs CΛ P <tr Φ - φ Φ H Φ 3 Φ OJ Φ Φ _α ≥; H CΛ rt d

0 d Φ rt- Φ d ^• »OJ φ HH h t3 H ιQ CΛ d Ό W h- ^■ ιQ Φ f 3 ri- ι-3

OJ Φ d rt ≥; H φ Φ 3 o tr Φ Φ Φ d ι-i Ό d H 2 N Φ ι- (rt 0J Φ H ¹ d Φ φ

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3 Ξ I- ^* rt Φ .30 3 -T3 Φ Φ s rt tr Φ ι-i 3 Φ H d rt Ό ι- (3 d ZHH OJ H rt

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3 α H Φ H tr h- '• P_ Hi α <ιQ ≤ H φ Φ s: Φ d Φ Φ Φ f CΛ d TJ tr o α OJ ι-S 0 Φ h-' c Φ d Φ O Φ d rt 3 φ Ii Φ ι-i ι-i φ tr rt rt ^ 3 o li 3 Φ tr o 3? T d φ PS ι-i H ι- (H tr ii Φ N Ό H tr rt d Φ ι-i Φ ^{) •} ! li o H 1— 'φ H 3 rϊ- N CΛ H tr J Φ i Z CΛ JHH Φ H d Φ rt o rt Φ

2 Φ Φ> rt J OJ rl- M Φ Φ d rt rt α Φ OJ φ I— ^* φ Φ ≤ d 0 ⁾ d 0 ^{) 1} tr ⁱ n

OJ * t HCH ^ li 3 D 3 HH CΛ ι-i Φ d ι-id tr H ¹ H Φ dddd 1- * Φ r-υ Φ ι-i

O Φ σ 1— 'C o_ N α OP CΛ CΛ OP rt; * r ιQ t- ¹ Φ I— ^* ι- (ι-i cn rt Φ tr d 0J t H ≤ Φ d H Ϊ φ 1 Φ lh Φ rr Φ Hi H- ^* Φ H Φ o Φ iQ d α * J3 - * t N ι-is: - 3 3 tr T Φ H Φ CΛ rt HS 3 OJ Φ (ϊ- Hi d H Φ do H ι- ( Φ Φ Φ 3 ≤ rt H CΛ 3 tu Φ dtod Φ OJ 3 tr 1— 'N Φ Φ tr H d OJ tr d H ι-h CΛ Φ H φ Φ z

2 3 tr ι-idp CΛ <£} Φ d 3 13- ι-i I— '≤ 3 Φ 3 3 • Φ H o H CΛ li α φ d Z rt Φ H Φ JO CΛ d 3 Φ 3 Φ d H CΛ CΛ 3 Φ h- ¹ CΛ O li 0J H

Φ 3 Φ Φ ι-s <N 2 iQ tr Φ rr 3 ιQ φ o Φ Ii φ li OJ rt L tr tϋ α O ι- (d OH Φ d Φ Φ - • HH ιQ T) H tr tr α J Ό d Φ J Φ H Φ tr

1 d H rt ι-i H 3 3 Hi o d 3 d OJ ι-i ÖD α d o Φ d

CΛ N CΛ Φ Φ 3 α d H d Φ o ι-i α rt Φ tr 3 d φ 1 7> CΛ rt Φ 1- H vQ H OJ H lf α 1 Ό Φ 3 d Φ Φ Φ 1 Φ Φ 1 H 3

1 ι-id Φ

Network participants have not been interrupted for a certain minimum time of, for example, 1.6 s. When the ring is opened, an "lmk-up *" telegram is sent to ports 1 and 2 of the redundancy manager in order to inform all other network participants in the series about the new ring structure. Test frames will continue det cyclically verses ^¬. Each network participant in the series resets the registers necessary for the telegram forwarding when it receives an "lmk-up * or" lmk-down * telegram.

A redundant implementation of the communication channels between two rows requires at least two separate communication paths. However, a maximum of one path may be used for data exchange between the rows. This potentially active communication channel between two rows is selected with the help of port select telegrams. If a potentially active communication channel is identified as faulty, it is deactivated and another communication path is switched to potentially active. The following applies to the switchover time from deactivated to potentially active:

Switching time> Δt imeout + Δt _rθ wdeiay. where Δt imeoit is the timeout interval and Δt _r oweiay corresponds to twice the worst case throughput time of a port select telegram through the series. The switchover time therefore depends on the number of network participants that form a row. It is, for example, for a series of 50 network participants in the order of 200 ms, if a timeout interval of 150 ms is assumed.

Redundancy in a three-dimensional network is also possible. If the loop structure already provides freedom from loops, ie there is no network redundancy, every potentially active communication path between two rows is also active. In this case, it is not necessary to use the modified tension tree algorithm described. In the case of network redundancy, the modified Spannmg tree algorithm places loop-free between the Rows sure. A reconfiguration of a network with the modified spanning tree algorithm is only necessary in the event of errors or network modifications that are not processed by the redundancy within a row or the redundancy of the communication channels between two rows.

In the case of a network with such network participants, the transmission time from the transmitter to the receiver depends on the number of network participants via which a telegram is forwarded and cannot be neglected. The transmission time of a telegram increases for everyone

Network subscriber who forwards the telegram by a subscriber-specific delay time Δti, which is composed of the following times:

1. Throughput time through the physical layer module, for example module 36 in FIG. 2, in the receiving direction from receipt of the first bit of a nibble until the nibble on the MII is output as valid in “RX_DV = 1 *. This time is, for example, 21 T _Bι t for DP83843 PHYTER of NSC, wherein T and _Blt ns at 100 Mbps transmission rate corresponds to 10 at 10 Mbps transmission rate 100 ns.

2. Time spent in the network participant from receiving a nibble to sending the same nibble. If the subscriber is currently sending its own telegram and a telegram has already been entered in the receive buffer, data forwarding can be delayed by up to (3k x 8) x T _B ιt compared to undisturbed operation.

3. Throughput time through the physical layer block, via which the telegram is forwarded in the send direction, from the first rising edge of a transmit

Clock signal after providing a nibble on the MII up to the first transmitted bit of this nibble. This lead time is, for example, for DP83843 PHYTER from NSC 6 T _B ιt. 4. Runtime over the lines between two neighboring network participants. The sum of the times specified under 1, 3 and 4 is a fixed _quantity and is referred to as the throughput time Δt _DlJ z. It can either be parameterized or measured by the network participants. A change in this throughput time Δt _D "is only possible if a network subscriber is removed from the network or added to the network or if the cabling is changed.

The throughput time Δt _D Lz can be determined with the following sequence of telegrams, which network participants execute, for example after initialization or on request:

1. Each network subscriber who is newly added to the network sends his or her neighboring network subscriber a so-called DLZ telegram, i.e. em first telegram for running time determination. This telegram is clearly identified in the 16 bit type address.

2. The new network participant starts a DLZ timer 1 after the last nibble of the type field of the DLZ telegram has been made available to the media independent interface (MII) of port 1 for sending. Accordingly, he starts a DLZ timer 2, 3 and 4 for sending via ports 2, 3 and 4. 3. Each of the maximum of 4 neighboring network participants starts after receiving the last nibble of the type field of the DLZ telegram on his MII its DLZ timer of the respective port. The received DLZ telegram is not forwarded, but is sent back to the sender supplemented by the residence tent in the respective Ethernet controller of the network participant. If this neighboring network participant has passed the last nibble of the type field of the DLZ telegram modified in this way to its MII directed to the newly connected network participant, it stops the DLZ timer and sends the stay tent stored in the DLZ timer with the data field of the telegram to the newly connected network participant.

4. The network subscriber newly added to the network stops the assigned DLZ timer 1, 2, 3 or 4 when he receives the last nibble of the type field at his MII of the respective port.

5. For example, for port 1 of the newly connected network participant, the throughput time Δt _D Lzι can be calculated using the formula: Δt _D Lzι = (T _DR -T _DA ): 2, with T _DR - response time measured with the DLZ timer 1 and T _DA - measured time spent in the neighboring network participants.

The throughput times Δt _D ι_z, Δt _D LZi and Δt _D Z4 are calculated in a corresponding manner for the remaining ports of the network subscriber newly added to the network. The flow tents determined in this way are stored as parameters in module 52 (FIG. 2).

6. With a further telegram, the newly connected network participant sends the measured throughput times to the neighboring network participants via the respectively assigned port.

The described determination of the throughput times is only necessary for every second network participant when initializing a network.

Time synchronization has the task of synchronizing the clocks of several or all network participants. The communication channels between network participants are advantageously operated in full duplex mode so that the transmission of telegrams exhibits deterministic behavior.

The transmission time from a sender to a receiver in a network depends on the number of network participants over which the telegram is routed and cannot be neglected. Time synchronization can be carried out with two special telegrams, for example. Figure 9 shows the general structure of a telegram. The first field 140 contains a destination address, ie an address of the subscribers to whom the telegram is directed, for example 48 bits long. The second field 141 contains a source address, the address of the sending network subscriber, the length of which is also 48 bits, for example. An identifier of the telegram is transmitted in a type field 142 with, for example, 16 bits. The user data of the telegram are sent in a data field 143 of variable length. The telegram is ended by a check sequence of 144, which essentially serves to check the transmission quality. Telegrams for time synchronization can be identified by a special multicast address as destination address 140 and / or by a new type address to be defined in type field 142.

FIG. 10 shows an order list which can be stored, for example, in the RAM 22 in FIG. 2. Telegrams that are to be transmitted via the network are entered in such an order list. If the transmission is not prioritized, the telegram below is transmitted next. It can therefore happen that, for example, a completed telegram 151 is only transmitted when two telegrams 152 and 153 previously entered in the job list have been transmitted. Depending on the number of pending orders, the delay in sending a telegram m a network subscriber after its entry m the order list is variable. In the following a possibility is described how the influence of the transmission time delay in the time synchronization can be avoided: 1. With a time master, ie em network participant, on whose clock the clocks of the other network participants are synchronized, it carries an SM-TimeO telegram, em first telegram for time synchronization, m an open entries list, starts a delay timer for each port P, P = 1, 2, 3, 4 and remembers the start time of these timers.

2. The delay timer of each port P, P = 1, 2, 3, 4, is stopped at the time master after the last nibble of the type field of the SM-TimeO telegram is available for sending to the MII of the respective port was asked. The transmission delay time is thus determined. A nibble is defined as half a byte, i.e. it is a sequence of 4 bits.

3. After receiving the last nibble of the type field of the SM-TimeO telegram on the MII of its port P, P = 1, 2, 3 or 4, each neighboring network participant starts its delay timer with the value of the respective throughput time Δt _D ι_z _{P /} which was previously measured by the method described above or entered by an operator. The address of the time master that was received as the source address in the SM-TimeO telegram is also saved. 4. At the point in time at which the neighboring network subscriber creates the last nibble of the type field of the SM-TimeO telegram for forwarding to the MII of another port, the value of the delay timer assigned to port P, P = 1, 2, 3 or 4, is stored. However, the delay timers continue to run. The stored delay times of the ports each correspond to the transmission time Δti defined above for this network participant. The delay of the telegram via the physical transmission has already been added by the start value Δt _D ι_z _{P of} the delay timer.

5. The time master then enters an SM-Timel telegram, which contains the start time of the delay timers in the data field, in the job list. Before sending this SM-Timel telegram via a port P, P = 1, 2, 3, 4, it replaces the start time of the delay timers with the time at which the last nibble of the type field of the SM-TimeO telegram the MII of this port for sending Grouting was made, ie by the sum of the start ^¬ the delay timer and the measured delay time time of each port P. In the SM Timel telegram is thus corrected by the time Sendezeitverzogerung carry emge-.

6. Each neighboring network participant that receives an SM-Timel telegram adds the stored delay time Δti of the SM-TimeO telegram previously forwarded via port P, P = 1, 2, 3 or 4 to that in the SM-Timel Received time and sends the time received in this way with an updated SM-Timel telegram via another port to the next neighbor. SM-Timel telegrams are only accepted by the network participant that previously sent an SM-TimeO telegram.

When the SM-Timel telegram is received, the time slave knows, i.e. the neighboring network participant, the start time of his delay timer. The synchronized time is the sum of the time received in the SM-Timel telegram and the delay time of the time slave for the respective receiving port. The neighboring network subscriber thus corrects the time received in the second telegram by the runtime and the reception time delay.

As an alternative to the option described above, the following procedure enables time synchronization with just one telegram:

1. The time master starts the delay timers assigned to the ports and carries the time telegram with the start time of these timers m the job list em.

2. The delay timer of each port P, P = 1, 2, 3, 4, is stopped at the time master after the last nibble of the type field of the time telegram is available for transmission to the media-independent interface of port P was made, ie after the last nibble of the type field was made available for physical transmission. The network participant then adds the ones in the time frame specified start time of the delay timer for the value of the delay timer of the respective port P and sends this sum as the time corrected by the transmission time delay with a first telegram for time synchronization via the respective port P.

3. Each neighboring network participant starts after receiving the last nibble of the type field of the first telegram for time synchronization on a port P,

P = 1, 2, 3 or 4, its assigned delay timer with the value of the respective throughput time Δt _DLZ E- It thus measures the time delay since receipt of the first telegram.

4. At the point in time at which the neighboring network subscriber creates the last nibble of the type field of the first telegram for time synchronization for forwarding to the MII of a port, the value of the delay timer which is assigned to this port is stored. However, the delay timers continue to run. The stored delay times assigned to the individual ports each correspond to the transmission time Δti of this network subscriber. It is added to the received start time of the delay timer and with a second telegram for time synchronization via another port to the next, i.e. forwarded to a third, network participant.

With the receipt of a first or second telegram for

The time slave knows the start time of its delay timer in time synchronization. The synchronized time results from the sum of the time received in a first or second telegram and the delay time of the time slave for the receiving port P.

The described possibilities for time synchronization can be used in a corresponding manner for the synchronization of interval timers in the network participants. The task of aquidistance timers is to enable several or all network participants to perform specified actions aquidistantly. This function is common in control systems referred to as "electronic wave *. For all network participants that are connected to one another via the network, a clock beat should be generated, with the clock of which respective target values are transferred and actual values are queried. An application example is the measurement of the electrical power if the required current and voltage measured values are recorded by separate transmitters and queried via a network.

It is assumed that an aquidistant cycle is controlled by only one aquidistance master. The network participant that takes over the function of an aquidistance master has a timer that is loaded at the start with the parameterizable value of the aquidistance interval. The timer is free running and is decremented with every bit clock. When the timer has expired, it is loaded again with the parameterized value of the aquidistance interval and a new cycle begins. The difference between an aquidistance timer and a watch is the direction of travel. To correct a timer status transmitted with telegrams, the

Time delays are not added as with the time, but are subtracted. The term "time synchronization *" used above should therefore be understood to include the synchronization of aquidistance timers.

The following options are available for synchronizing active actions:

1. The aquidistance master carries the aquidistance telegram m the order list e. It saves the value of the aquidistance timer when the last nibble of the type field of the aquidistance telegram is transferred to the MII of the four ports P, P = 1, 2, 3, 4, ie it is made available for physical transmission , This value Δt _{A Jι} stored for each port P, which corresponds to the time remaining until the aquidistance interval has expired, is sent with the aquidistance telegram via port P to the neighboring network subscriber. 2. After receiving the last nibble of the type field of the aquidistance telegram at the MII of a port, ie when receiving the aquidistance telegram from the physical transmission link, each network participant starts an auxiliary timer with the value of the throughput time Δt _D _.zp -

3. The value of the auxiliary timer is saved at the point in time at which the neighboring network subscriber creates the last nibble of the type field from the aquidistance telegram for forwarding to the MII of another port. The stored value of the auxiliary timer corresponds to the transmission time Δti of this network participant for port P. This stored time Δt _x is subtracted from the received remaining time Δt _AqJ ι until the next cycle _begins . The neighboring network participant forwards the corrected remaining time (Δt _Aquι - Δt with the aquidistance telegram via the other port to the next neighboring network participant. In addition, he loads the corrected remaining time into his aquidistance timer, which is decremented with each cycle. 4. If the Aquidistanz-Timer of an Aquidistanz-Slave has expired, it is first loaded with the parameterized value of the Aquidistanz-Interval and decremented with every bit clock in the manner described, the remaining time (Δt _AqJ1 - Δt ₂ ) until the next cycle begins m the aquidistance timer.

For the described synchronization of aquidistance timers, the maximum transmission time between a transmitter and a receiver in the network should be less than the length of the aquidistance interval.

In the exemplary embodiment, a network was described according to the Ethernet specification. However, the invention is also readily applicable to Fast Ethernet, Gigabit Ethernet or other types of networks.

Claims

claims

1. Network with several network participants, wherein a first network participant is designed to send a first telegram for time synchronization to a second network participant, which stores the transit time of the telegram over the physical transmission link between the first network participant and the second network participant that the first telegram contains a time of the first network participant corrected for a transmission time delay, and that the second network participant is designed to measure the time delay since receipt of the first telegram and to correct the time received in the first telegram by the throughput time and the reception time delay.

2. Network according to claim 1, characterized in that the second network participant is further configured to send a second telegram for time synchronization to a third network participant, the one by the lead time and the delay time between receipt of the first telegram and transmission of the second telegram corrected received time contains.

3. Network with a plurality of network participants, a first network participant being designed to send a first telegram for time synchronization to a second network participant, which stores the transit time of the telegram over the physical transmission link between the first network participant and the second network participant, that the first network subscriber is further configured to store a time of the first network subscriber corrected by a transmission time delay of the first telegram, that the second network subscriber Participant is designed to measure the time delay since receipt of the first telegram, the first network participant being further configured to send a second telegram, which contains the time of the first network participant corrected for the transmission time delay, to the second network participant, and the second Network subscriber is also designed to correct the time received in the second telegram by the throughput time and the delay in reception time.

4. Network according to claim 3, characterized in that the second network participant is further configured to forward the first telegram to a third network participant, to measure its delay time of the telegram forwarding and to send em third telegram to the third network participant, which is one by the throughput time and the delay time of the telegram forwarding of the first telegram contains corrected received time.

5. Network according to one of the preceding claims, characterized in that the first network participant has a first timer (57) for determining the transmission time delay, which he starts when entering a telegram m, a list of the transmission orders and after providing the telegram for physical transmission as the value of Reads out the transmission time delay at which the time at which the telegram m the list of send orders was entered is to be corrected.

6. Network according to claim 5, characterized in that the second network participant has a second timer for determining the reception delay, which it starts upon receipt of a first telegram from a physical transmission link.

7. Network according to claim 6, so that the throughput time of the telegram over the physical transmission path between the first network participant and the second network participant is stored as the starting value m the second timer before it starts.

8. Network according to one of the preceding claims, characterized in that the beginning and end of the throughput time of a telegram are each determined as the time at which em characteristic field of a telegram with a fixed distance from the beginning of the telegram em Media Independent Interface of the first participant, or m em media independent interface of the second network participant.

9. Network according to claim 8, d a d u r c h g e k e n n z e i c h n e t that the network meets the Ethernet, Fast Ethernet or Gigabit Ethernet specification and that the characteristic field of the telegram is the type field.

10. Network according to one of the preceding claims, characterized in that the first network participant is further configured to send the network em first telegram after the recording m to determine the runtime to an adjacent participant and a response time timer after providing the telegram for physical transmission start that the second network participant is further trained to start a timer for determining the stay time after receiving a telegram for determining the runtime from the physical transmission and to stop the timer after providing a second telegram for physical transmission and to measure the measured stay tent t _DA m second telegram for running time determination to transmit to the first network participant that the first network participant is further designed to receive the second Telegram to determine the response time timer from the physical transmission, to evaluate the measured response time t _D and the measured stay time t _{DA of} the second network participant and to determine a throughput time t _D Lz of the physical transmission

"_ ( ^L DR ^{~ t} DA) ^l DLZ ^~

11. Network subscriber, in particular field device, for a network according to one of the preceding claims, since you are characterized in that several ports, in particular four ports (28 ... 31), are provided for connecting further network components, that an interface (25) a so-called microprocessor interface is provided for connecting the ports to an internal processor bus (21) that a control unit (46), a so-called switch control, is provided for routing the telegram between the ports and the microprocessor interface and that Network subscriber is designed to send a first telegram for time synchronization to a second network subscriber as time master, which contains a time corrected by a transmission time delay of the network subscriber, and / or that the throughput time of a telegram is transmitted in the network subscriber as a time slave the physical transmission path between the N Network subscriber and a second network subscriber is stored and that the network subscriber is designed to measure the time delay since receipt of a telegram for time synchronization and to correct a time received in a telegram by the throughput time and the reception time delay.

12. Network subscriber according to claim 1, dadurchgekennzeic hn et that the ports (28 ... 31) meet the Ethernet, Fast Ethernet or Gigabit Ethernet specification.

13. Network subscriber according to claim 12, d a d u r c h g e k e n n z e i c h n e t that the control unit (46) is designed such that a transmission priority of the telegrams to be sent is evaluated and that telegrams with high priority are sent before telegrams with low priority.

14. Network subscriber according to one of claims 11 to 13, that a microprocessor (23) is present for correcting an internal clock using m telegrams of received time information.