WO2007147974A1

WO2007147974A1 - Device for communicating between slave modules of a telecommunication network

Info

Publication number: WO2007147974A1
Application number: PCT/FR2007/001025
Authority: WO
Inventors: Michel Combat
Original assignee: ABB FRANCE (Sociéte par actions simplifiée)
Priority date: 2006-06-21
Filing date: 2007-06-20
Publication date: 2007-12-27
Also published as: FR2902955B1; FR2902955A1

Abstract

Communication device (IA) of a telecommunication network (10), able to be connected, by a serial type link, to a first slave module (2A, I), and, by an Ethernet type link, to at least one second communication device (IB) and to a master module (8), said communication device comprising serial-Ethernet conversion means, characterized in that it comprises a memory (5A, 6A) able to store data transmitted by said first slave module and/or by said at least one second communication device, said transmitted data being exchanged independently of said master module (8).

Description

COMMUNICATION DEVICE BETWEEN SLAVED MODULES OF A TELECOMMUNICATION NETWORK

The subject of the present invention is a device and a method of communication between slave modules of a telecommunication network.

In a telecommunication network using a master-slave protocol, the communication between the modules of the network is managed by a master module, which initiates communications with slave modules. The slave modules are not able to exchange data between them without passing through the master module.

There are "multi-master" protocols that allow the coexistence of several master modules on the network. However, master modules do not usually exchange data with each other.

The MODBUS protocol is a master-slave protocol based on a request-response system. This protocol defines the structure of the messages and their mode of exchange. It is implemented in layer 7 (Application) of the ISO model (Open Systems Interconnection). The MODBUS protocol is used on serial links, for example of the RS232, RS285 or optical fiber type, and can be implemented in two forms, RTU (Remote Terminal Unit) and ASCII (American Standard Code for Information Interchange). With the MODBUS / RTU protocol, all the data is exchanged in binary, and, with the MODBUS / ASCII protocol, the data is exchanged in ASCII form.

One of the recent evolutions of the MODBUS protocol is the implementation of this protocol on the Ethernet network. This new protocol, called the MODBUS / TCP protocol, works similarly to the MODBUS protocol, uses the same function codes (read / write) and an equivalent frame format. The RTU frame data is encapsulated in the Ethernet frame at the Transmission Control Protocol / Internet Protocol (TCP / IP) TCP layer. The MODBUS / TCP protocol retains the master-slave concept and the request-response architecture.

For a user, the MODBUS protocol has the advantage of being simple to implement, since it is sufficient to know the number of the slave module and the address of the data to be recovered.

However, the master-slave structure is a limit to a more dynamic and efficient use of data exchanges.

The present invention aims to provide a device and a communication method between slave modules of a telecommunications network using a master-slave protocol, for example the MODBUS protocol.

For this purpose, the subject of the invention is a communication device of a telecommunication network, capable of being connected, by a serial type link, to a first slave module, and, by an Ethernet type connection, to least a second communication device and a master module, said communication device comprising serial-Ethernet conversion means, characterized in that it comprises a memory capable of storing data transmitted by said first slave module and / or by said at least one second communication device, said transmitted data being exchanged independently of said master module. Advantageously, a communication between said first communication device and said first slave module uses the MODBUS protocol.

Preferably, a communication between said first communication device and said at least one second communication device uses the MODBUS / TCP protocol.

According to one embodiment of the invention, a communication between said first communication device and said at least one second communication device is performed by sending a broadcast message on the Ethernet link, by said first communication device. .

The subject of the invention is also a method of communication between a first slave module of a telecommunication network and at least a second slave module of said telecommunication network, said telecommunication network comprising a master module, said first slave module being connected to a first communication device of said telecommunication network, said at least one second slave module being connected to at least one second communication device of said telecommunication network, said first and at least one second communication devices being connected together, said method comprising the steps of:

a) receiving and storing in said first communication device data to be transmitted from said first slave module to said second slave module, b) transmitting from said first communication device to said at least one second communication device said data to be transmitted. stored in step a), c) storing in said at least one second communication device said data to be transmitted received in step b), and d) transmitting from said at least one second communication device to said at least one second slave module said data to be transmitted. stored in step c), e) the steps a) to d) being performed independently of the master module.

Advantageously, step a) comprises the sub-steps of: f) transmitting from said first communication device to said first slave module a data request to be transmitted, and, g) in said first communication device, storing as data to transmit the data received from the first slave module in response to said request.

According to one embodiment of the invention, step b) is performed automatically at predetermined time intervals.

According to one embodiment of the invention, step b) is performed when new data to be transmitted are stored in said first communication device.

The invention will be better understood, and other objects, details, features and advantages thereof will appear more clearly in the following detailed explanatory description of an embodiment of the invention given as a purely illustrative and non-limiting example, with reference to the appended schematic drawing.

On these drawings: FIG. 1 is a simplified schematic view of a telecommunication network comprising three communication devices according to one embodiment of the invention; and

FIG. 2 is a block diagram showing the steps of a communication method between slave modules of the telecommunications network of FIG. 1.

Figure 1 shows a telecommunications network 10 comprising a master module 8 and three communication devices 1 _A, 1 _B and _c. It will be noted that the number of communication devices 1 is not limiting.

The communication device I _A will now be described in more detail. The device I _A is connected by a cable 11 to a subnet _10A of the network 10, via a communication port 3 of the serial link type. The serial link is for example of the RS232, RS485 or optical fiber type and uses the MODBUS protocol (ASCII or RTU). The subnet 10A includes three slave modules 2 _A, i, 2 _A, 2 _A and _{_2,} 3. Note that the number of modules 2 _A slave is not limiting. The slave modules 2A _{, I} , 2A, ₂ and 2 _As3 use the MODBUS protocol. The device _1A is connected by a cable 12 to an Ethernet network, via a communication port 4 of the Ethernet link type. The Ethernet network is represented in FIG. 1 by a communication bus 13. The Ethernet link uses the MODBUS / TÇP protocol. It will be noted that the support of the Ethernet link may be of the radio, cable or optical fiber type, for example.

The Ethernet link allows broadcast message transmission using, for example, the User Datagram Protocol (UDP). A "broadcast" message, or broadcast message, is a message sent to the attention of several devices. In the example, a broadcast message sent by the communication device 1 _A is sent to the attention of the communication devices 1 _B and _1c . This type of message does not require a response, the management of a non-reception being the responsibility of the recipient.

The device 1 _A comprises means of conversion between communications using the MODBUS protocol and communications using the MODBUS / TCP protocol. In other words, the device 1 _A performs a gateway function between the MODBUS / TCP communications of the Ethernet link and the MODBUS communications of the serial link.

The devices I _B and Ic are identical to the device 1 _A. The device lβ is connected by a cable 14 to a sub-network 10β of the network 10, via a communication port 3 of the serial link type. Subnet 10β comprises four slave modules 2 _B , i, 2 _{B; 2} , 2 _{B, 3} and 2β, ₄ using the MODBUS protocol. The device I _B is connected by a cable 15 to the Ethernet network, via a communication port 4 of the Ethernet link type. The device _1c is connected by a cable 16 to a sub-network _10c of the network 10, via a communication port 3 of the serial link type. The sub-network 10c comprises two slave modules 2c _{; 1} and 2Q ₂ using the MODBUS protocol. The device _1c is connected by a cable 17 to the Ethernet network, via a communication port 4 of the Ethernet link type.

The steps of the communication method between slave modules 2 belonging to different subnets will now be described. By way of example, consider a data transmission from the slave module 2 _Ajl to the slave module 2 _{B; 1} and a data transmission from the slave module 2 _Aj2 to the slave module 2c, ₁ . It is obvious that this method allows the transmission of data from any set of slave modules 2 to any set of slave modules 2, each data transmission being performed between two slave modules 2 belonging to sub-modules. different networks 10 _A , 10 _B , IOQ. It will be noted that this method makes it possible to transmit data from a slave module 2 to a plurality of slave modules 2. This method also makes it possible to simultaneously carry out several data transmissions between several pairs of slave modules 2, respectively. This method is executed independently of the master module 8, that is to say without intervention of the master module 8, which may be in operation for other tasks. The synchronism of the master module 8, in particular, is not used.

In step 100, the device 1 _A sends a data request to be transmitted to the slave module 2A, _I. In other words, the devices 1 _A requests the slave module _2A, i to communicate the data it wishes to transmit to another slave unit, e.g. 2β slave _module, i. Similarly, the device 1 _A sends a data request to be transmitted to each of the other slave modules of the subnet _10A , that is to say the slave modules 2A ₂ and

2A, 3- In step 101, the device 1 builds a local _A data table _A from 6 responses issued by the slave modules _2A; i, 2 ₂ and _A 2 _{A 3} in response to requests and a configuration table 5a _of the device _1A. The data table _6A , which is stored in the device _1A , contains in particular the data to be transmitted from the slave module 2 _Ajl to the slave module _2B, i and the data to be transmitted from the slave module 2 _Aj2 to the slave module _2C _{; 1} .

In step 102, the device 1 _A sends a broadcast message on the Ethernet network, the broadcast message containing all or part of the data table _6A . Step 102 can be performed automatically at predefined time intervals. Alternatively, step 102 may be performed when the contents of data table _6A are changed.

In step 103, the broadcast message is received by the device 1 _B and by the device Ic- The device I _B (respectively the device Ic) compares, using a decision system 7 _B of the device 1 _B

(respectively of the device Ic), the received data and the data stored in the configuration table 5 _B of the device 1 _B

(The device 1 _c ) - The device 1 _B (respectively the device Ic) in particular checks the consistency write and read data so as not to write on data defined in reading.

When an association is possible between the received data and the data of the table _5B of the device _1B (respectively of the device _1c ), the data are written in the local data table _6B of the device _1B (respectively of the device l ( _c ).

In step 104, the data stored in the table 6 _B of the device 1 _B are transmitted by the device 1 _B to the slave module 2 _{B) 1} , through the serial communication port 3 of the device 1 _B and the MODBUS protocol. Similarly, the data stored in the table 6c of the device Ic are transmitted by the device 1 _c to the slave module 2c _, i, through the serial communication port 3 of the device _1c and the MODBUS protocol. _A device 1 also allows transmission of data from the slave module 2 _A, _I to the slave module 2 _{A 2.}

Step 100 is similar to what has been described previously.

In step 101, the data table 6 _A , which is stored in the device 1 _A , contains in particular the data to be transmitted from the slave module 2 _Ajl to the slave module 2 _{A, 2} -

Steps 102 and 103 are deleted.

At step 104, the data stored in the table 6 _A of the device 1 _A is transmitted by the device 1 _A to the slave module 2 _A2 through the serial communication port 3 of the device 1 _A and MODBUS protocol .

Thus, data can be exchanged between slave modules 2 without any intervention of the master module 8 of the network 10, which makes it possible to increase the speed of transmission of the data. Each communication device 1 allows several slaves 2 to which it is connected to exchange data with each other without requiring the presence of the master module 8 on the network 10.

In other words, each communication device 1 behaves like a gateway having an additional function of communication between two slave modules 2. The installation cost of the network 10 can be reduced, in particular because it is no longer necessary to have a master module.

The device 1 also has the advantage of not modifying the operation of the network 10, that is to say the communications between the master module 8 and the slave modules 2. With respect to the master module 8, the device 1 is has as a slave module. Local data tables _6A, _6B, _6C are accessible by the master module 8. similarly, the data coming from the slave modules 2 are accessible to the master module 8 via the corresponding communication device 1 which in this case ensures a standard gateway function, namely the conversion of the MODBUS / TCP protocol into MODBUS on a serial line (ASCII or RTU).

The transmission rate of the broadcast messages can be set independently for each communication device I _A , I _B and I _c . In other words, a communication device I _A, I _B OR _C 1 may frequently transmit broadcast messages while another communication device 1 _A, I _B and l _c rarely transmitted.

Each communication device 1 _A, I _B OR _C 1 may be configured to initialize the data from its data table 6 _A, 6 _B, 6 _C when no message is received for a predefined time. This function makes it possible to put the device 1 in degraded mode when the communication between slave modules 2 connected to it is suspended.

It should be noted that this method is well suited to a network using the MODBUS protocol, since it makes it possible to maintain the flexibility of the MODBUS protocol for the user. However, the communication method could be used on a network using another master-slave protocol. In this case, the communication devices must comprise links using the corresponding protocol.

Although the invention has been described in connection with a particular embodiment, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

Claims

1. Communication device (1 _A ) of a telecommunication network (10), capable of being connected, by a serial type link, to a first slave module (2 ^ ₁ ), and by an Ethernet-type link , at least one second communication device (1 _B ) and a master module (8), said communication device comprising serial-Ethernet conversion means, characterized in that it comprises a memory (5 _A , 6 _A ) capable of storing data transmitted by said first slave module and / or by said at least one second communication device, said transmitted data being exchanged independently of said master module (8).

2. Device according to claim 1, characterized in that a communication between said first communication device ( _1A ) and said first slave module (2 ^ ₁ ) uses the MODBUS protocol.

3. Device according to claim 1 or 2, characterized in that a communication between said first communication device ( _1A ) and said at least one second communication device (I _B ) uses the MODBUS / TCP protocol.

4. Device according to any one of claims 1 to 3, characterized in that a communication between said first communication device (1 _A ) and said at least one second communication device (1 _B ) is performed by the transmission a broadcast message on the Ethernet link, said first communication device.

5. A method of communication between a first slave module (2 _{A) 1} ) of a telecommunication network (10) and at least one second slave module (2 _B , i) of said telecommunication network, said telecommunication network comprising a module master (8), said first slave module being connected to a first communication device (I _A ) of said telecommunication network, said at least one second slave module being connected to at least one second communication device (1 _B ) of said network telecommunication, said first and at least one second communication devices being connected to each other, said method comprising the steps of: a) receiving and storing in said first communication device data to be transmitted from said first slave module to said at least one a second slave module, b) transmitting from said first communication device to said at least one s a second communication device said data to be transmitted stored in step a), c) storing in said at least one second communication device said data to be transmitted received in step b), and d) transmitting from said at least a second communication device to said at least one second slave module said data to be transmitted stored in step c), e) the steps a) to d) being performed independently of the master module (8).

6) Method according to claim 5, characterized in that step a) comprises the substeps consisting of: f) transmitting from said first communication device ( _1A ) to said first slave module (2 ^ ₁ ) a data request to be transmitted, and, g) in said first communication device, storing as data to be transmitted the data received of the first slave module in response to said request.

7. The method of claim 5 or 6, characterized in that step b) is performed automatically at predetermined time intervals.

8. The method of claim 5 or 6, characterized in that step b) is performed when new data to be transmitted are stored in said first communication device.