EP0716398A2 - Interface circuit for franking machine and method for manipulation-proof print data control - Google Patents

Abstract

The interface circuit has transmission and reception registers for holding parallel transmitted data and a shift register for series/parallel and parallel/series data conversion of the transmitted data within an actuator/sensor control. Sensors (251, 252) and actuators (12, 26) within the base are coupled to a base register (28) connected to the meter, with sensor signals transferred in a shift register of the actuator/sensor control. A sensor status register group is supplied with the parallel data relating to the sensor signals of at least one sensor, with detection of any modification of the received bits of the sensor signal to provide an interrupt signal.

Description

The invention relates to an internal postage meter interface circuit and a method for manipulation-proof print data control according to the type specified in the preamble of claims 1, 13, 16 and 23.

Franking machines have at least one transport device, input, storage and display means and a print control unit for a printing device, which prints printing patterns on a recording medium which is moved to this printing device and is to be printed. Printing devices of this type, in particular for electrothermal printing by means of an ink ribbon or transport devices, are equipped with actuators and sensors which are controlled or queried via a circuit arrangement (US Pat. No. 4,746,234).

For example, sensors that detect the transport of the record carrier trigger the printing process. Other sensors determine the position of the counter pressure roller or monitor the ongoing printing process.

A shaft of the transport device or spool of a color carrier, which is moved relative to the recording medium and which transmits the color particles, is coupled to an encoder, which provides clock signals for printing control during the printing process. All sensors or actuators are directly or indirectly connected to the control unit, in particular a microprocessor control unit, via a special circuit arrangement.

For a thermal transfer printing process, a switching unit for a printhead which contains resistive elements is already known from DE 38 33 746 A1. A selective control with preheating of the resistance elements serves to reduce the heating power during printing. To control a print head, energy is provided in a defined manner for the individual pixels of the print image and a print pattern is printed on a recording medium to be printed that is relatively moved relative to the ink ribbon, in that the ink ribbon transfers the color particles from the ink layer to the recording medium when the associated heating resistor in the print head is heated.

Inkjet printers are also suitable for franking mail. According to the printing principle used, the circuit arrangement must be adapted to the required actuators and sensors.

An ASIC is known from EP 465 236 A2, which comprises a circuit for pressure control, engine control and billing. The circuit for pressure control comprises a memory for fixed and another for variable data, which are overlaid with the fixed data. A motor controller is provided for actuating a motor drive depending on the mail item feed. A sensor that supplies speed signals is connected to the pressure controller via the motor controller. An advantage is undoubtedly the high security against manipulation resulting from the limited number of starting points for manipulation due to the use of a single ASIC. A disadvantage of using a single ASIC is the lack of usability for different franking machines, which have a different pressure control module corresponding to a realized franking machine system or post office.

However, if different types of franking machines are to be produced, then a large number of circuits (ASICs or / and other components) must be provided. The large number of components and circuits in particular offers starting points for manipulation if no alternative effort is made and a safety housing is used. The franking machine types differ in shape and equipment according to the amount of mail to be processed and thus also with regard to a different number of sensors and actuators.

EP 231 452 A2 discloses the periodic polling of sensors in accordance with a software routine of a central processing unit (CPU), preferably a microprocessor.

The disadvantage of this solution is a high computing time due to the periodic scanning of the sensors. This disadvantage is further increased if the query is particularly time-critical. In order to be able to react to a change of state as quickly as possible, the polling frequency must be set high. The microprocessor therefore spends a large proportion of its computing time on the query.

In US 5,267,172 a serial interface in a franking machine has already been proposed, which is arranged between a microprocessor and an ASIC and on which address, command and data are serially transmitted to the ASIC. It is disadvantageous that time-critical queries cannot be implemented and the interface does not work automatically, which ties up computing time in the microprocessor.

The last-mentioned disadvantage also applies to a data processing system known from US Pat. No. 5,199,105. For a universal asynchronous receiver / transmitter module, a first shift register for outputting the data and a second shift register for reading in the data as well as a programmable comparison register are proposed to trigger an interrupt when a certain data byte is received via the serial channel.

The task is to develop an interface circuit internal to the franking machine, which avoids the disadvantages of the prior art and can be implemented inexpensively for a large number of franking machine variants without reducing the security against manipulation.

A sub-task is to query the sensors by the control device of the postage meter machine or to control the actuators, on the one hand, cost-effectively and, on the other hand, in such a way that less computing time of the CPU is tied up.

Another sub-task is the development of a print data control system, which means that less CPU processing time is tied up and functional and manipulation security is maintained.

The object is achieved with the features of claims 1, 13, 16 and 23.

The invention is based on the consideration of improving the adaptability of the electronic control to different types of franking machines by means of an interface circuit internal to the franking machine.

Within a security housing, a microprocessor of a first circuit part, in which only security-relevant data are processed, is connected to a second circuit part according to the invention, in which the remaining data are traded for the respective type of franking machine. This second circuit part forms an internal franking machine interface to the first circuit part. The internal interface franking machine is advantageously designed as a system-specific ASIC.

It is assumed that the microprocessor of the first circuit part accesses the second circuit part to control an electronic print head and the actuators or sensor query. The microprocessor polls or transmits data non-periodically.

The circuit part for security-relevant data is designed identically for all types of franking machines. The second circuit part (ASIC) for the other data is designed as an internal interface to the first circuit part, depending on the type of franking machine.

The second circuit part (ASIC), i.e. The internal franking machine interface circuit is equipped with transmission and reception registers for storing data transmitted in parallel and with a shift register for the series / parallel or parallel / series conversion of data transmitted within an actuator / sensor control in the meter and has two lines on the output side, in particular a transmission and a reception line to the base of the franking machine, by means of which data is transmitted serially between the meter and a register unit in the base within the franking machine. Sensors and actuators of the base are connected to the register unit. Sensor signals are pushed into the shift register of the actuators / sensor control and are available there in parallel. A sensor status register group for parallel data of the sensor signals of at least one sensor is provided as the reception register. At least one sensor status register and at least one interrupt control register are connected to a monitoring circuit in order to monitor the received bits of the sensor signals for a change in status in order to trigger an interrupt to the control unit.

In addition, the franking machine interface circuit has a decoder for providing the memory control signals for the actuator / sensor control and a first state machine and a pressure data controller within the actuator / sensor controller. The aforementioned decoder, the actuator / sensor control and the print data control each contain control or data registers.

Within the ASIC, the corresponding data can be made available in a known manner in parallel in the status register or in the command register for a sensor query and for setting the actuator. Furthermore, only serial interfaces to the base are advantageously provided, which enable a system expansion for a large number of sensors and actuators in accordance with the various franking systems. Due to the small number of lines to the base, it is possible to create an inexpensive solution for this and for a meter / base separation.

The state machine implemented in hardware automatically scans the sensors and loads a status register and sets the actuators according to the data stored in the command register.

According to the invention, an interrupt control is connected between the control unit (CPU) and status register, the data lines from the status register to the control unit (CPU) being formed in parallel. If the status register has been loaded under hardware control, the interrupt controller evaluates individual bits. A predetermined state or state transitions of the individual bits are immediately communicated to the control unit (CPU) by an interrupt request.

It is envisaged that the actuator / sensor control has a first state machine, which is intended that on the one hand by the Sensor signals supplied to the register unit are pushed into the shift register of the actuators / sensor control and can then be called up there in parallel, that on the other hand parallel data for actuators from command register groups are loaded in parallel into the shift register and then read out serially to supply the actuators in the base so that the actuators are read out / Sensor control and the monitoring circuit are connected to the control unit (CPU), that the interrupt control register and the control unit (CPU) are designed to preset the type of change in the sensor value, on the basis of which an interrupt request is triggered, in the interrupt control register and to execute an interrupt accordingly, so that the control unit (CPU) can branch directly into the corresponding sensor handling routine.

The advantage of such non-periodic polling or transmission of data from the interrupt controller connected to the control unit (CPU) is that the control unit (CPU) saves computing time. Another advantage is that the control unit (CPU) no longer has to be informed which sensor has changed its value. The information about the sensor is communicated to the control unit (CPU) during the interrupt processing, so that it can branch directly into the corresponding sensor handling routine. The type of change in the sensor value on the basis of which an interrupt request is triggered can be preset, so that in addition to the sensor itself, the type of sensor transition is also known from the interrupt request without having to query the sensor value in the status register.

Before the interrupt controller is more advantageous Interrupt control register switched in order to influence the type of interrupt triggering. The change in the value of a sensor line can thus generate an interrupt on the processor. In addition, the control unit (CPU) does not require any synchronization when setting the actuators with regard to the serial transmission between meter and base.

To create a print data control according to the further subtask, the internal franking machine interface circuit with transmission and reception registers for the storage of data transmitted in parallel and with a shift register for the serial / parallel or parallel / series conversion of the data transmitted from or to the print head via a print register, equipped.

According to the invention, the print data control is expanded to a security module and, in addition to the desired relief of the control unit CPU, also offers greater security against manipulation before fraudulent use of the print head in connection with special print head electronics. According to the invention, a code is generated independently of one another in each code generator of a unit, ie in the printhead electronics and in the security module, and each code is transmitted to the other unit. Comparators check the received activation or acknowledgment code with the expected code. If correct, the printhead is activated for a single print image. The image to be printed is then transmitted in "plain text" (unencrypted). After the data transfer is complete, the print head is automatically locked again and must be activated with the help of another coded data exchange. A new, coded data record for activation or acknowledgment is generated for each print image, thus recording the activation process cannot be reused.

According to the invention, it is provided in a further variant that the print data controller has a third state machine, which is connected on the input side to a mode register group for setting the operating mode and on the output side to control inputs of the transmit shift register, a test circuit and a pressure register in order to output a code generator which can be switched on insert the second acknowledgment code under the control of the third state machine into a test shift register, the second shift code being available in parallel in the test shift register and the test circuit being designed according to a set security printer mode, the serial data transfer between the print head electronics print register on the one hand and the transmit shift register on the other to monitor in order to monitor the received bits for a predetermined change in state, possibly an interrupt to the control unit and thus a DMA-controlled e Trigger print data transfer to the print head.

Figur 1,

Blockschaltbild der Schaltungsanordnung für Meter und Base,

Figur 2,

Blockschaltbild der frankiermaschineninternen Schnittstellenschaltung,

Figur 3,

Blockschaltbild für die erfindungsgemäße Aktoren/Sensoren-Steuerung,

Figur 4,

Überwachungsschaltung mit Verbindung der Aktoren/Sensoren-Steuerung über eine Interrupt-Steuerung in der frankiermaschineninternen Schnittstellenschaltung mit der Steuereinheit,

Figur 5,

Blockschaltbild für eine erste Variante der erfindungsgemäßen Druckdatensteuerung mit Testschaltung,

Figur 6,

Blockschaltbild für eine zweite Variante der erfindungsgemäßen Druckdatensteuerung mit Sicherheitsmodul.

Advantageous developments of the invention are characterized in the subclaims or are shown in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. Show it:

Figure 1,

Block diagram of the circuit arrangement for meter and base,

Figure 2,

Block diagram of the franking machine internal interface circuit,

Figure 3,

Block diagram for the actuator / sensor control according to the invention,

Figure 4,

Monitoring circuit with connection of the actuator / sensor control via an interrupt control in the franking machine internal interface circuit with the control unit,

Figure 5,

Block diagram for a first variant of the print data control according to the invention with test circuit,

Figure 6,

Block diagram for a second variant of the print data control according to the invention with a safety module.

FIG. 1 shows a block diagram of a circuit arrangement for a franking machine. The circuit arrangement can be assigned to two parts, namely meter and base, the base containing at least the motors and other actuators, sensors and the printhead together with the associated control electronics. As the first circuit part, the meter contains the actual control, which is connected to an input / output module 4, and in particular to a second circuit part, of the interface circuit according to the invention, which is advantageously configured as an ASIC 14. The control comprises in a known manner a clock / date block 8, a character memory 9, a cost center memory 10, a non-volatile memory 5, program memory 11 and working memory 7, which are in communication with a microprocessor.

In the clock / date block 8, time data and the date are generated even when the franking machine is switched off. The input / output module 4, for example, establishes a connection to the modem 23 and possibly to the scale 22 via an RS 232 interface.

The latter can be part of the base. In addition, the display controller 3 and the keyboard 2 are connected to the module 4.

The input data are stored in the non-volatile memory (NVM) 5 so that the last setting is retained before the franking machine is switched off. The operating program and fixed data, for example for an advertising cliché, are stored in the program memory 11. Depending on the cost center, the current accounting data is stored in the cost center memory 10 before each print.

The corresponding character set is present in the character memory 9. Corresponding characters are stored in the pixel memory 7 as pixel data.

The microprocessor is used as a control unit 6 for the entire franking machine and is connected to blocks 4, 5, 7 to 11 of the first circuit part 1 via address lines A and data lines D and via address, data and control lines (A, D, S) connected to the second circuit part 14, which is designed as an ASIC. In accordance with the memory control signals S _s generated in the decoder of the ASIC, the above-mentioned blocks are addressed by the microprocessor.

The function-determining blocks - shown in FIG. 1 - of the first circuit part can be partially or totally combined into at least one physical component and further measures can be provided to make manipulation by unauthorized persons more difficult. The function of these blocks and such measures are explained in more detail, for example, in German application P 43 44 476.8.

The invention is explained in more detail in the following embodiment together with FIGS. 2 to 5.

The circuit part 14 - shown in more detail in FIG. 2 - for the franking machine internal interface, which is designed in accordance with the franking machine type, has a decoder 300 for providing the memory control signals, an actuator / sensor controller 400, an interrupt controller 600 and a print data controller 700. The address lines A0 to A3 and data lines D and control lines S are connected to all blocks 300, 400, 600 and 700. Address lines A13 to A19 are also present on the decoder. Decoder 300 provides memory control signals S _s for blocks 400, 600 and 700. The block 400 for the actuator / sensor control outputs a signal I _i on the output side to the block 600 for the interrupt control. The block 600 is connected on the output side to the control unit 6 via the lines for the data and control signals I _o (FIG. 1). The ASIC circuit part 14 is equipped with an input s for connection to the sensors of the base and with an output a for connection to the actuators of the base of the franking machine via a register unit 28 (FIG. 1).

The monitoring of the sensors and the switching or setting of the actuators is supported by the function of the actuator / sensor control 400 shown in FIG. 3. In order to relieve the control unit 6, the reading in of the sensor states and the output of control bits for the actuators is automated by a first state machine 401. The circuit contains register groups 410 to 450, comprising registers on the one hand for communication with the control unit (CPU) 6 and on the other hand for the state machine 401.

The entire actuator / sensor control 400 consists of a first state machine 401, two 8-bit command register groups 420 and 421, two 8-bit (sensor) status register groups 410 and 411, a shift register 430 for serial transmission of the actuator or sensor data, a mode register group 440 for setting the operating mode and an interrupt control register group 450 for influencing the interrupt generation in a logic circuit 490.

The interrupt controller 600 and the logic circuit 490 form a monitoring circuit (shown in more detail in FIG. 4) in order to send the signal I _o to the control unit 6 when the state changes on the connecting line. This allows an internal interrupt to be generated for the control unit 6. The logic circuit 490 of the actuator / sensor control 400 consists of at least one XOR logic gate, which has the first input with the Q output of a D flip-flop of the interrupt control register group 450 and the second input with the Q output of one D flip-flops 4101 of the (sensor) status register group 410 is connected. Each XOR gate of the logic circuit 490 is connected in terms of output via a signal line I _i to the associated input of the interrupt controller 600 of the postage meter internal interface circuit. The associated input is preferably a clock input of at least one D flip-flop of a register group 610, which is connected to its D input with plus potential. The Q output of the D flip-flops of register group 610 is connected to an associated input of a priority encoder 620, which interacts with a second state machine (state machine) 601. In the event of an interrupt request determined by the priority encoder 620, the second state machine 601 sends a request signal IRQ to the control unit 6, which responds with a response signal IACK at a given time which is dependent on the control unit. The control unit 6 can then query data D from the priority encoder 620 via the data lines, by means of which the interrupt source can be determined.

In the preferred embodiment variant, the interrupt generation takes place on the basis of the four low-order bits of the 8-bit (sensor) status register group 410. The logic circuit 490 is preferably designed as an XOR logic operation and, in accordance with the aforementioned exemplary embodiment, has four XOR logic operation gates, which correspondingly include four D flip-flops of register group 610 are connected. The register groups of all blocks 300, 400, 600 and 700 can - in a manner not shown - form a separate block 500 within the ASIC 14, which is in communication with the other blocks.

In the base, the register unit 28 is equipped with a large number of shift registers 281 to 286 (FIG. 1). According to the manner shown in FIG. 3, the register unit 28 has two sensor shift registers 281 and 282 assigned to the sensors 251 and 252, and two actuator shift registers 283 and 284, which together with the shift register 430 of the actuator / sensor control 400 form one Loop are coupled. The sensors 251 and 252 present in the base supply data to the sensor shift registers 281 and 282.

The franking machine loads the value from the first command register 420 into the shift register 430 under the control of the first state machine 401.

When the data is shifted out, the data of the first sensor shift register 281 of the base are received in the shift register 430 and the data of the second sensor shift register 282 are shifted into the first sensor shift register 281. After completion of the shift, the contents of shift register 430 (former data from sensor 251) are loaded into the first 8-bit (sensor) status register group 410. If the interrupt control register group 450 is set accordingly, this loading can lead to an interrupt.

The value from the second command register group 421 is now loaded into the shift register 430 and transmitted serially. The content is shifted from the first actuator shift register 283 into the second actuator shift register 284. At the same time, the bits received are transferred from sensor shift register 281 (data from sensor 252) to second 8-bit (sensor) status register group 411.

The contents of the actuator shift registers 283 and 284 are then loaded into the corresponding actuator registers 285, 286 and the actuators are switched in accordance with the bit value. Simultaneously with the copying of the actuator information, the sensor shift registers 281 and 282 are reloaded with the corresponding sensor level of the sensors 251 and 252. This completes a run through the state machine 401.

In a second variant - not shown in the figures - a sensor 25 is assigned to the two sensor shift registers 281 and 282, as a result of which the sensor signal can be evaluated with a higher resolution. Likewise, an actuator 26 could be connected to both actuator shift registers 283, 284 via the latches 285, 286 to realize a more precise setting.

In a third variant (not shown), a large number of sensors can be used, for example, a microswitch 250 for detecting the end position during the printing process, sensor 251 for letter detection, sensor 252 for strip dispenser ... and others. Sensors are connected which have a rough resolution, possibly for the purpose of reflecting a pure switching function.

In a fourth variant (not shown), a large number of sensors of a low resolution or for the purpose of reflecting a pure switching function can be connected together with a sensor 253 for a higher resolution, which allows the sensor amplitude to be evaluated.

The actuators can be connected in the same variety. If a solenoid or a motor 12 requires only 1 bit or a motor for two directions only 2 bits, an actuator shift register and associated actuator register can be provided for amplitude, time, frequency or data presetting.

Likewise, threshold values for threshold-dependent detection can be specified for a sensor using actuator shift registers and associated actuator registers, which only compares the threshold value with an actual value and transmits the bit of the comparison result to the sensor shift register. An amplitude can also be evaluated in this way, but with a large number of sensors.

In a fifth variant - which has not been shown separately in the figures - the actuator sensor controller (400) is connected via at least one line connected to the register unit (28) in the base in order to either query sensor signals or to issue actuator signals for setting the actuators.

A sensor for time-critical data is the encoder 13. On the one hand, this is - in the manner shown in FIG. 1 - directly at the input e of the control unit 6 and on the other hand is connected to the input e of the second circuit part (ASIC) 14. The encoder acts on a DMA controller present in the control unit 6. The DMA controller reads a complete stamp image from the pixel memory (RAM) 7 and reads it into the print register (DR) of the print head 16 in print column fashion via the ASIC print data controller 700. The encoder 13 acts directly on the print data controller 700 by supplying an external trigger signal for the transfer of the print data for the individual print columns to a second state machine 701.

The print data control 700 is explained in more detail in FIG. 5 for a first variant. A third state machine 701 is connected to a transmission shift register 710 and to a test shift register 720 in order to take over the control of the data transfer by means of a signal CLOCKOUT. The transmit shift register 710 sends the bytes supplied by the DMA controller to the print register (DR) 15. Here, the data for the print head electronics of the print head 16 are converted into a series-parallel format. The print head 16 contains registers for intermediate storage of the parallel print data, which registers with a signal LATCH are controlled in accordance with the encoder signal at input e, and drivers which are controlled by a signal STROBE from control unit 6. The drivers control the actual printing elements of the print head 16.

The serial data transfer can be monitored in the ASIC 14 in connection with the first circuit part 1 on the basis of a test circuit 702. The test shift register 720 can receive data from the pressure register 15 serially, which can be read by the control device 6 via the data line D after serial-to-parallel conversion.

In addition, the serial data transfer can be tested in the ASIC 14 in connection with the first circuit part 1 due to a local loop and by means of the test circuit 702. For this purpose, it is provided that the bits of the transmit shift register 710 for serial print data are read in during the pauses for testing via a local loop LOCAL LOOP and by means of a test circuit 702 in a test shift register 720.

The operating mode can be set by the control unit 6 via the data line D by means of special mode registers 750 shown in FIG. The number of bytes, the type of transfer (with or without byte counter) and the clock rate of the shift clock can thus be predetermined.

Additional registers can be provided in the register block 500 of the ASIC 14 and, in conjunction with the third state machine 701, can output further data, clock or control signals to the printer register 15 and the printhead electronics, so that control is also possible when using different printheads.

The problem regarding the security against manipulation of a printhead arranged externally from the meter in the base was solved with the help of a special printhead electronics and with special circuit measures solved in the print data control unit 700, which relieve the control unit 6 of pressure monitoring tasks. An activation for a single print image is realized. Activation signals or monitoring data can also be transmitted separately, but this would be more complex than with a serial transmission.

FIG. 6 shows a block diagram for a second variant of the print data control according to the invention with a training as a security module. The print data control unit 700 connected to an expanded printhead hardware - in accordance with the embodiment shown in FIG. 5 - is expanded to include a second code generator 703, a multiplexer 709, a demultiplexer 725 and a second comparator 723. In addition, the - shown in FIG. Printhead hardware expanded by printhead electronics 30, which include a first code generator 32, a demultiplexer 35, a first comparator 33, a monitoring module 36 for monitoring print data length for a single activated print image, first and second switch means 34, 37 and a fourth state machine 31.

The modification of the expanded printhead hardware compared to the print data control unit shown in FIG. 3 results on the one hand from a very large number of print data to be transmitted, for example 200 dpi (dot per inch) for a print column. The transmission shift register 710 shown in FIG. 5 and the print register DR 15 must also be designed for data transmission for a print column. Column printing is preferably carried out on an envelope if the print column data is applied in parallel to the print head and a STROBE signal is switched to the print head.

On the other hand, the special printhead electronics meet a need for security against manipulation. Before the start of printing, an activation code is transmitted from the print data controller in the meter to the special print head electronics in the base. Under the control of the fourth state machine 31, the activation code, which is temporarily stored in the print register 15 after a series / parallel conversion, is applied to a first comparator 33 via a demultiplexer 35. Under the control of the fourth state machine 31, a predetermined code is generated by the first code generator 32 and fed to the first comparator 33, which carries out a comparison. In the event of a positive comparison, an activation signal is applied to a monitoring module 36 for monitoring the printing data length for a single activated printing image. Otherwise the print head remains locked. Simultaneously with the aforementioned activation, the predetermined code is fed via first switch means 34 to the print register 15, which serially transmits the predetermined code as an activation code to the print data control unit 700. Field-effect transistors or other comparable controllable electronic switches are preferably suitable as the first switch means 34.

According to the invention, such a version of a print data controller 700 has a third state machine 701, which is connected on the input side to a mode register group 750 for setting the operating mode and on the output side to control inputs of the transmit shift register 710, a test circuit 702 and the external print register 15 by one of a first switchable code generator 32 issued acknowledgment code under the control of the third state machine 701 into a test shift register 720. The acknowledgment code is available in parallel in the test shift register 720 and the test circuit 702 is designed in accordance with a set security printer mode to monitor the serial data transfer between the print register 15, printhead electronics 30 on the one hand and the transmit shift register 710 on the other hand in order to monitor the received bits for a predetermined change in state monitor. A monitoring circuit is formed by the second comparator 723 and the interrupt controller 600. A second input of a priority encoder 620 shown in FIG. 4 is acted upon by a second D flip-flop 611 with the signal J which is output by the second comparator 723 and which signals a match. If there is a match, an interrupt is generated by the interrupt controller 600.

Thus, if necessary, an interrupt can be transmitted to the control unit 6 in order to subsequently trigger a print data transmission to the print head. If the transfer is started via the DMA channel, it runs automatically without the involvement of the control unit 6 (CPU). This also relieves the control unit 6 (CPU).

The internal franking machine interface circuit is equipped with send and receive registers for the storage of data transmitted in parallel and with a shift register for the serial / parallel or parallel / serial conversion of the data transmitted from or to the print head via a print register.

• a) Durchführung eines codierten Datenaustausches, wobei in der Druckkopfelektronik 30 und in der Druckdatensteuereinheit 700 unabhängig voneinander ein einzigartiger Code erzeugt und jeweils zur anderen Einheit 30, 700 übertragen wird,
• b) Überprüfen der empfangenen Freischalt- bzw. Quittungscode mit dem erwarteten Code mittels Vergleicher, wobei bei Korrektheit der Druckkopf für ein einzelnes Druckbild freigeschaltet und das zu druckende Bild dann übertragen wird,
• c ) Überwachen des von der Druckkopfelektronik 30 übermittelte Codes in der Druckdatensteuereinheit 700 und Bildung eines Interruptsignals bei Korrektheit, wobei das Interruptsignal zur Steuereinheit 6 übertragen wird, um damit anschließend eine DMA-gesteuerte Druckdatenübertragung zum Druckkopf auszulösen,
• d) automatisches Sperren des Druckkopfes nach Beendigung der Datenübertragung für vorgenanntes einzelnes Druckbild und
• e) Erzeugung eines neuen codierten einzigartigen Codes zur Freischaltung bzw. Quittierung, um den Druckkopf wieder für ein folgendes Druckbild freizuschalten.

The procedure for manipulation-proof print data control is characterized by the steps:

• a) performing a coded data exchange, wherein in the print head electronics 30 and in Print data control unit 700 independently of one another generates a unique code and is respectively transmitted to the other unit 30, 700,
• b) checking the received activation or acknowledgment code with the expected code by means of a comparator, the print head being activated for a single print image and the image to be printed then being transferred if it is correct,
• c) monitoring the code transmitted by the printhead electronics 30 in the print data control unit 700 and forming an interrupt signal if correct, the interrupt signal being transmitted to the control unit 6 in order to subsequently trigger a DMA-controlled print data transfer to the printhead,
• d) automatic locking of the print head after completion of data transmission for the aforementioned individual print image and
• e) Generation of a new coded unique code for activation or acknowledgment in order to activate the print head again for a subsequent print image.

The print head is activated for exactly one print after checking the received activation code. Print data length information is transmitted to the print head as part of an encoded data exchange, which includes the length of the image to be printed in bytes or in a predetermined number of print columns. The aforementioned print data length information is preferably transmitted from the demultiplexer DEMUX 35 to the monitoring module 36 for monitoring the print data length before the print data transmission signal transmitted to the print head contains the unencrypted image data. In the state of activation, a print data length monitoring is carried out for the unencrypted image data in order to terminate the data transmission for the aforementioned to determine the individual print image. The locking of the print head is triggered when the print data length specified by the aforementioned print data length information is reached.

A method for manipulation-proof print data control, according to another version works with several generated codes simultaneously. It is provided that to carry out the coded data exchange, codes are generated independently of one another in order to compare the code transmitted to the print head electronics with a generated first code and to compare the code transmitted to the print data control unit with a second code.

According to the invention, the above-mentioned other version for such a print data controller 700, designed as a security module, has a second code generator 703 for generating two activation codes unique to each print and a third state machine 701, which has a mode register group 750 on the input side for setting the operating mode and control outputs on the output side of the transmit shift register 710, a test circuit 702 and the external print register 15 is connected in order to insert a second acknowledgment code emitted by a first connectable code generator 32 into a test shift register 720 under the control of the third state machine 701. The second acknowledgment code is available in parallel in the test shift register 720 and the test circuit 702 is designed in accordance with a set security printer mode to monitor the serial data transfer between the print register 15, printhead electronics 30 on the one hand and the transmit shift register 710 on the other hand in order to check the received bits for a predetermined change in state to monitor. Thus, if necessary an interrupt can be transmitted to the control unit 6 in order to subsequently trigger a print data transmission to the print head. If the transfer is started via the DMA channel, it runs automatically without the involvement of the control unit 6 (CPU). This also relieves the control unit 6 (CPU).

In the print data control unit 700, which relieve the control unit 6 of pressure monitoring tasks, it is provided that a first input is connected to the parallel output of the test shift register 720 and a second input of a digital comparator 723 for checking the second acknowledgment code is connected to the parallel output of a second code generator 703 , wherein the data bits of the second acknowledgment code that can be called up in parallel are compared with the data bits of a first activation code supplied by the second code generator 703 and an error message is transmitted to the monitoring circuit (723, 600) if they do not match. The inputs of the digital comparator (723) are preferably provided with internal buffer memories for temporary storage before the code is checked. An XOR link is used internally again.

The control unit CPU 6 is connected to the transmit shift register 710 via a DMA channel. If the aforementioned codes, which are present at the second comparator 723, match, the transmission of the error message to the interrupt controller 600 is interrupted and a match is signaled instead. To report the match, a signal J is transmitted to the interrupt control (600). An interrupt is then generated by the interrupt controller 600 and sent to the control unit CPU 6, which causes the control unit CPU 6 Print data is transmitted to the transmit shift register 710 via the DMA channel.

A multiplexer MUX 709 is connected between the transmission shift register 710 and the second code generator 703 or the control unit CPU 6 in order to load the second activation code or the print data transmitted via the DMA channel into the transmission shift register 710.

With the help of a special printhead electronics and with special circuit measures, an activation for a single print image is realized by arranging the printhead electronics 30 between the print register DR 15 and the printhead 16 and after the activation, the print data transfer to the print register DR 15 via the printhead electronics 30 to the printhead 16 under Monitoring is carried out by the printhead electronics 30.

The print head electronics 30 has a fourth state machine 31, which is supplied with a clock signal CLOCKOUT from the third state machine 701 on the input side and an output signal from a monitoring module 36, and on the output side with a control input of a first electronic switch 34, with a control input of a second electronic switch 37, is connected to a first code generator 32 and to a control input of a demultiplexer DEMUX 35, an internal buffer of the print head DK 16 being connected to a first output of the demultiplexer DEMUX 35 for parallel data transfer.

It is further provided that at the parallel output of the first code generator 32 a first input and at the second output of the demultiplexer DEMUX 35 a second input of a digital Comparator 33 for checking the activation code is connected, the data bits of the second activation code that can be called up in parallel being compared with the data bits of a first acknowledgment code supplied by the first code generator 32, and if there is a mismatch, an error message is sent to the monitoring module 36 that the monitoring module 36 otherwise, if there is a match, the fourth state machine 31 of the demultiplexer DEMUX 35 switches over to an internal buffer of the monitoring module 36 for parallel data transmission via its first output.

The monitoring module DLC 36 preferably has counters in order to carry out pressure length monitoring in columns or byte-by-column fashion. The counter DLC 36 generates an output signal to the fourth state machine 31 when a predetermined printing length is reached.

The fourth state machine 31 acts on the control input of the second electronic switch 37 in order to switch off a signal LATCH supplied by the encoder 13 from the internal buffer of the print head DK 16 when a predetermined print length is reached, so that no further print data can be printed by the print head DK.

It is furthermore provided that the fourth state machine 31 acts on the control input of the first electronic switch 34 and a second acknowledgment code is read into the print register by the first code generator 32 and is transmitted to the print data control 700. The inputs of the digital comparator 33 are advantageously provided with internal buffer memories for temporary storage before the code is checked.

Since this internal franking machine interface circuit to the base forms a number of serial interfaces with any expansion options, this enables adaptation to the most varied franking systems and to the base of each franking machine, on the one hand for sensor query and for actuator setting, with a non-periodic query by a microprocessor 6 and with an interrupt controller 600 and on the other hand for a print data controller 700 with operating mode setting and test options.

The different systems require differently designed decoders 300 and thus different ASICs. Relative system independence can, however, be achieved using an additional decoder 900, shown in dashed lines in FIG. 1, ie if the internal decoder 300 is used only partially or not in order to control the blocks of the first circuit part for security-relevant data by means of memory control signals S _s .

The invention is not limited to the present embodiment. Rather, a number of variants are conceivable which make use of the solution shown, even in the case of fundamentally different types.

Claims (26)

Interface circuit internal to the postage meter machine equipped with send and receive registers for the storage of data transmitted in parallel and with a shift register for the series / parallel or parallel / series conversion of data transmitted, characterized in that a) that equipped with the aforementioned transmit and receive registers actuator / sensor control (400) has a first state machine (401), the input side with a mode register group (440) for setting the operating mode and the output side with control inputs of the shift register (430) and is connected via control lines to an external register unit (28) in order to load sensor signals (LOADEXTERNAL) at least from the connected sensors (25, 250, 251, ...) and under control of the first state machine (401) into the shift register (430 ) to insert (SHIFTCLOCK), b) that a sensor status register group (410) for at least one sensor (25, 250, 251 ...) is connected to the shift register (430), sensor signals being available in parallel and c) that at least one sensor status register (4101) of the aforementioned group (410) and at least one interrupt control register (450) are connected on the input side to a monitoring circuit (490, 600) which has a logic circuit (490) with XOR logic in order to determine the bits received monitor the sensor signals for changes in status in order to trigger an interrupt to the control unit (6). Interface circuit internal to the postage meter machine according to claim 1, characterized in that the actuator / sensor control (400) and the monitoring circuit (490, 600) are connected to the control unit (6), that the interrupt control register (450) and the control unit (6) are designed and programmed to preset the type of change in the sensor value on the basis of which an interrupt request is triggered in the interrupt control register (450) and to execute an interrupt accordingly, so that the control unit (6) can branch directly into the corresponding sensor handling routine. Interface circuit internal to the postage meter machine according to claims 1 and 2, characterized in that the monitoring circuit consists of an interrupt control (600) and a logic circuit (490), that the logic circuit (490) with XOR logic is connected to the interrupt control (600) and a signal I _i to the interrupt controller (600) provides that the interrupt controller (600) has a second state machine (601) which is controlled by a priority encoder (620) in order to emit an interrupt request signal. Interface circuit internal to the postage meter machine according to claims 1 to 3, characterized in that the monitoring circuit (490, 600) is logically linked in order to monitor the low-order bits of the sensor signals for a change in state, in order to thereby trigger an interrupt to the control unit (6). Interface circuit internal to the postage meter machine according to one of the preceding claims 1 to 4, characterized in that a sensor (25) is assigned to the two sensor-slide registers (281 and 282) of the register unit (28), with which the sensor signal is transmitted with a higher resolution can evaluate several bits. Interface circuit internal to the postage meter machine according to one of the preceding claims 1 to 4, characterized in that a multiplicity of sensors, in particular a microswitch (250) for detecting the end position during the printing process, a sensor (251) for letter detection, a sensor (252) for strip sensors and / or other sensors are connected to the register unit (28), which have a rough resolution, possibly a bit for the purpose of reflecting a pure switching function. Interface circuit internal to the postage meter machine according to one of the preceding claims 1 to 4, characterized in that a plurality of sensors of a low resolution, possibly for the purpose of reflecting a pure switching function, are connected together with a sensor (253) for a higher resolution, the sensor (253) for a higher resolution, the evaluation of the amplitude of the measured variable is permitted. Interface circuit internal to the franking machine according to claim 1, characterized in that the shift register (430) is equipped with two lines on the output side to the base of the franking machine, with which data is transmitted serially between the meter of the franking machine and the external register unit (28) in the base Register unit (28) actuators (12, 26) are connected so that in the actuator / sensor control (400) command register groups (420, 421) are connected to the shift register (430) in order to present data in parallel for actuators from command register groups (420, 421) into the shift register (430) in parallel, which are then read out under the control of the first state machine (401) serially for supplying the actuators in the base, with actuator shift registers (283, 284) for series / Parallel conversion is provided so that the sensor shift registers (281 and 282) assigned to the sensors (251 and 252) are connected in parallel el / series conversion are provided, and that the register unit (28) in the base is equipped with a large number of shift registers (281 to 286), which with the shift register (430) of the actuator / sensor control (400) in the franking machine are coupled in a loop. Interface circuit internal to the postage meter machine according to one of the preceding claims 1 to 8, characterized in that an actuator (26) is connected via the latches (285, 286) of the register unit (28) to both actuator shift registers (283, 284) for a more precise setting to realize. Interface circuit internal to the postage meter machine according to one of the preceding claims 1 to 8, characterized in that a plurality of actuators of a low resolution, possibly for the purpose of reflecting a pure switching function, are provided, in particular a solenoid or a motor (12) for one or two directions which is used for Control requires only a few bits, and that an actuator with a high resolution is provided, that the actuators can be controlled together with an actuator shift register and that the actuator with a high resolution and an associated actuator register for an amplitude-time, frequency or Data presetting is provided. Interface circuit internal to the postage meter machine according to one of the preceding claims 1 to 8, characterized in that in the register unit (28), by means of actuator shift registers and at least one associated actuator register, threshold values for a threshold-dependent detection for a sensor are specified, which only compares the threshold value with an actual value and transmits the bit of the comparison result to the sensor shift register. Interface circuit internal to the postage meter machine according to one of the preceding claims 1 to 8, characterized in that corresponding measures are provided in the register unit (28) in the case of a plurality of sensors in order to be able to evaluate an amplitude. Interface circuit internal to the postage meter machine with transmission and reception registers for the storage of data transmitted in parallel and with a shift register for the parallel / series conversion of data, characterized in that in a print data controller (700) a third state machine (701) on the input side with an encoder signal and with DMA control signals and a signal from a mode register (750) is applied and that the third state machine (701) controls the shift register (710) and optionally a test circuit (702) and cooperates with the control unit (6) so that the operating mode of the print data control (700 ) is set and that checking means (702, 6) for checking the mode of operation are formed in accordance with the set operating mode. Interface circuit internal to the postage meter machine according to claim 13, characterized in that an operating mode is set for the test circuit (702) via special mode registers (750) and via the third state machine (701) in order to test the bits of the transmission shift register (710) for serial print data via a read local loop into a test shift register (720), whereby a series / parallel conversion takes place and that the control unit (6) is programmed, the testing in connection with means (4, 5, 7 to 11) of a first circuit part (1) in to take the printing breaks. Interface circuit internal to the postage meter machine according to claim 13, characterized in that the number of bytes, the type of transfer and / or the clock rate of the shift clock can be preset via mode registers (750). Interface circuit internal to the franking machine equipped with send and receive registers for storing data transmitted in parallel and with a shift register for the serial / parallel or parallel / serial conversion of the data transmitted from or to the print head via a print register, characterized in that
that a print data controller (700) has a third state machine (701) which is connected on the input side to a mode register group (750) for setting the operating mode and on the output side to control inputs of the transmission shift register (710), a test circuit (702) and a pressure register (15) is to insert an acknowledgment code emitted by a first connectable code generator (32) under control by the third state machine (701) into a test shift register (720), whereby the emitted acknowledgment code is available in parallel in the test shift register (720) and the Test circuit (702) is designed according to a set security printer mode to monitor the serial data transfer between print register (15), printhead electronics (30) on the one hand and the transmit shift register (710) on the other hand, and a monitoring circuit (723, 600) is designed to monitor the received bits to be monitored for a predetermined change in state hen to possibly trigger an interrupt to the control unit (6) and thus to trigger a print data transfer to the print head. Interface circuit internal to the postage meter machine according to Claim 16, characterized in that a first input is connected to the parallel output of the test shift register (720) and a second input of a digital comparator (723) for checking the acknowledgment code is connected to the parallel output of a second code generator (703), wherein the data bits of the acknowledgment code that can be called up in parallel are compared with the data bits of an activation code supplied by the second code generator (703), and a signal J is transmitted to the interrupt controller (600) for notification if they match. Interface circuit internal to the postage meter machine according to claims 16 to 17, characterized in that the control unit CPU (6) is connected to the transmission shift register (710) via a DMA channel, with an interrupt being sent to the control unit CPU 6 causing the control unit to cause the control unit CPU 6 via the DMA channel print data are transmitted to the transmission shift register 710. Interface circuit internal to the postage meter machine according to claim 16, characterized in that a print head electronics (30) is arranged between the print register DR (15) and the print head (16) and after the activation the print data transfer to the print register DR (15) via the print head electronics (30) to the print head ( 16) under the supervision of the printhead electronics (30). Interface circuit internal to the franking machine according to claim 16, characterized in that - That the printhead electronics (30) has a fourth state machine (31) which is acted upon on the input side with a clock signal CLOCKOUT by the third state machine (701) and by a monitoring module (36) with an output signal and on the output side with a control input of a first electronic switch (34 ), with a control input of a second electronic switch (37), with a first code generator (32) and with a control input of a demultiplexer DEMUX (35), with an internal buffer at a first output of the demultiplexer DEMUX (35) for parallel data transfer the print head DK (16) is connected, - That at the parallel output of the first code generator (32) a first input and at the second output of the demultiplexer DEMUX (35) a second input of a digital comparator (33) for checking the activation code is connected, the data bits of the activation code which can be called up in parallel are compared with the data bits of an acknowledgment code supplied by the first code generator (32) and if there is a mismatch, an error message is sent to the monitoring module (36) that the monitoring module (36) will otherwise be activated if there is a match and that the fourth state machine (31) of the demultiplexer DEMUX (35) for parallel data transmission is switched over its first output to an internal buffer of the monitoring module (36),
that the monitoring module has a counter DLC (36) in order to carry out pressure length monitoring in columns or byte-by-column fashion. Interface circuit internal to the franking machine according to claim 20, characterized in that - That the counter DLC (36) generates an output signal to the fourth state machine (31) when a predetermined pressure length is reached, that the fourth state machine (31) acts on the control input of the second electronic switch (37) in order to reach a predetermined pressure length from Switch off the encoder (13) supplied signal LATCH from the internal buffer of the print head DK (16), so that no further print data can be printed by the print head DK. - That the fourth state machine (31) acts on the control input of the first electronic switch (34) and a second acknowledgment code is read from the first code generator (32) into the print register, which is transmitted to the print data control (700). Interface circuit internal to the postage meter machine according to one of the preceding claims 16 to 21, characterized in that a multiplexer MUX (709) is connected between the transmission shift register (710) and the second code generator (703) or the control unit CPU (6) in order to use the activation code or to load the print data transmitted via the DMA channel into the transmission shift register (710) and that the inputs of a digital comparator (723, 33) are provided with internal buffer memories for temporary storage before the code is checked. Method for manipulation-proof print data control, by means of at least partially encrypted information, characterized by the steps: a) carrying out a coded data exchange, a unique code being generated independently of one another in the printhead electronics (30) and in the print data control unit (700) and each being transmitted to the other unit (30, 700), b) checking the received activation or acknowledgment code with the expected code by means of a comparator, the print head being activated for a single print image and the image to be printed then being transferred if it is correct, c) monitoring the code transmitted by the printhead electronics (30) in the print data control unit (700) and formation of an interrupt signal if correct, the interrupt signal being transmitted to the control unit (6) in order to subsequently trigger a DMA-controlled print data transfer to the printhead, d) automatic locking of the print head after completion of data transmission for the aforementioned individual print image and e) Generation of a new coded unique code for activation or acknowledgment in order to activate the print head again for a subsequent print image. Method according to Claim 23, characterized in that, for carrying out the coded data exchange, codes are generated independently of one another in order to compare the code transmitted to the print head electronics with a generated first code and to compare the code transmitted to the print data control unit with a second code. Method according to Claim 23, characterized in that in the state of activation, a print data length monitoring is carried out for the unencrypted image data in order to determine the termination of the data transmission for the aforementioned individual print image and that the blocking of the print head is triggered as soon as a print data length specified by a print data length information is reached . Method according to claim 23, characterized in that the print data length information is transmitted to the print head as part of a coded data exchange, the code including the length of the image to be printed in bytes or as a predetermined number of print columns and in a monitoring module (36) for monitoring the print data length is transmitted before the print data transmission signal transmitted to the print head contains the unencrypted image data.

Images