JP2016184791A - Communication controller and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication controller capable of reducing the component cost because a dummy unit is not required, and the supervisory function can be centralized, capable of detecting unauthorized connection of an electronic apparatus with a communication system, and the communication system is less likely to fall into communication disabled state.SOLUTION: A communication controller 5 is connected with a network, through which a plurality of communication devices connected with a pair of communication lines of trunks 3b, 3c, perform communication, respectively, and mediates communication between the networks. The communication controller includes shortening circuits 22a-22c for shortening the rising or falling time of the communication signal waveform on the communication line, close to the limit of establishing communication, transmission sections 20a-20c transmitting a test signal for determining whether or not the communication is established in the network, at a predetermined time, and judgement sections 21a-21c for judging whether or not the communication is established when the transmission sections 20a-20c transmit the test signal in the network, and the shortening circuits 22a-22c are turned on.SELECTED DRAWING: Figure 2

Description

  The present invention includes a trunk line having a pair of communication lines and a plurality of communication apparatuses connected to the pair of communication lines, and a plurality of networks each communicating with the plurality of communication apparatuses are connected, and communication between networks And a communication system including the communication control device.

  In a vehicle, a large number of mounted electronic devices are connected via a communication line and communicate with each other to perform cooperative operation, thereby realizing vehicle travel control, vehicle interior environmental control, and the like. In mounted electronic devices, CAN (Controller Area Network) is widely adopted as a communication protocol.

  In general, in a communication system that employs a CAN communication protocol, a twisted pair cable in which a pair of communication lines are more combined is used. Each electronic device performs communication using a differential signal, and a dominant is detected when a potential difference between a pair of communication lines exceeds a threshold value, and a recessive is detected when the potential difference is equal to or less than the threshold value.

  In general, a communication system employing a CAN communication protocol employs a bus-type network topology, and each electronic device is connected to a trunk line used for communication in common with other electronic devices. . For example, each electronic device performs data transmission / reception with a dominant corresponding to data 0 and a recessive corresponding to data 1.

  In the communication system, even if the CAN communication protocol is adopted, electronic devices having different communication protocols in detail cannot directly communicate with each other. For this reason, in a communication system including electronic devices with different communication protocols, a network is composed only of electronic devices that can perform direct communication, and the networks are connected by a gateway (communication control device). Communication between devices is configured such that a gateway mediates.

  In a network adopting a CAN communication protocol, ringing occurs when an electronic device transmits to another electronic device. Ringing is caused by multiple reflection of a signal due to impedance mismatching at a branch portion from the main line and impedance mismatching of a communication device.

Ringing also occurs as vibration associated with overshoot and undershoot even when the impedance between communication lines is small and the rise or fall time of the communication signal waveform is too short (the rise or fall of the waveform is steep). When the vibration waveform exceeds the dominant / recessive threshold, the effect increases.
If the influence of ringing becomes large in the network, a failure occurs in communication, and if the failure is large, there is a possibility that communication may become impossible.

  In recent years, as wireless devices have become smaller and lighter, unauthorized electronic devices have been connected to the in-vehicle communication system without permission from the vehicle owner, and the privacy of the vehicle owner, such as a stopover location, has been infringed. Or, the driving operation may be disturbed, and Patent Document 1 discloses a local area network for solving such a problem.

  In the local area network disclosed in Patent Document 1, a plurality of electronic control units are connected to each other, and the capacitance on the network configuration is increased in the vicinity of a threshold value at which communication on the local area network is established. Means are provided. The capacitance increasing means is, for example, a dummy electronic control unit connected to the local area network in parallel with the electronic control unit, and includes an inductor and a capacitor.

JP 2013-133303 A

In the local area network as disclosed in Patent Document 1, a dummy electronic control unit is required separately, and there is a problem that the cost of parts increases. Also, because it is normally used at the permissible limit of ringing, it is subject to monitoring for each vehicle in order to monitor electronic devices that are likely to fall into a communication impossible state due to external influences and that are likely to cause ringing. There is a problem that the electronic devices are different.
Moreover, since the ECU (Electronic Control Unit) that can be monitored is limited to an ECU that easily causes ringing, for example, there is a problem that the ECU that is to be monitored cannot be unified.

  The present invention has been made in view of the circumstances as described above. Since no dummy unit is required, the cost of components does not increase, and the monitoring function can be unified, so that the costs of components and software can be reduced, and the communication system is illegal. An object of the present invention is to provide a communication control device that can detect that an electronic device is connected and that the communication system is unlikely to fall into a communication disabled state due to external influences.

  According to the present invention, the ECU having the shortening circuit can be adjusted so that ringing greatly occurs. For example, the functions can be unified with respect to the communication control device connected to a plurality of buses. Since the monitoring function can be unified, the component cost and the software cost can be reduced, it is possible to detect that an unauthorized electronic device is connected to the communication system, and it is difficult to fall into a communication impossible state due to an external influence. An object is to provide a communication system.

  A communication control apparatus according to the present invention includes a trunk line having a pair of communication lines and a plurality of communication apparatuses connected to the pair of communication lines, and a plurality of networks each communicating with the plurality of communication apparatuses are connected. In the communication control device that mediates communication between the networks, a shortening circuit that shortens the rise or fall time of the communication signal waveform on the communication line in the network to the vicinity of the limit at which communication is established; A transmitter for transmitting a test signal for determining whether or not communication is established at a predetermined time to the communication line, the transmitter transmits a test signal in the network, and the shortening circuit Each of the networks includes a determination unit that determines whether or not communication is established when it is on.

  The communication control device includes a trunk line having a pair of communication lines, and a plurality of communication devices connected to the pair of communication lines, and a plurality of networks each communicating with the plurality of communication devices are connected to each other. Mediate communication. The shortening circuit for each network shortens the rise or fall time of the communication signal waveform on the communication line in the network to near the limit where communication is established, and whether the transmission unit for each network establishes communication within the network. A test signal for determining whether or not is transmitted to the communication line at a predetermined time. The determination unit for each network determines whether or not communication is established when the transmission unit transmits a test signal in the network and the shortening circuit is on.

  The communication control apparatus according to the present invention is characterized in that the transmitting unit is configured to transmit a test signal during non-communication on the trunk line.

  The communication control device according to the present invention further includes a display unit that displays that communication within the network is impossible when the determination unit determines that communication is not established, and the shortening circuit includes The rising or falling time is changed stepwise.

  In this communication control device, when the determination unit determines that communication is not established, the display unit displays that communication within the network is not possible. The shortening circuit changes the rising or falling time of the communication signal waveform on the communication line in the network in stages.

  In the communication control device according to the present invention, after the network integration is completed, each time the transmission unit transmits a test signal, and the shortening circuit changes the rising or falling time stepwise, the determination unit By determining whether or not communication is established, a rise or fall time in the vicinity of the limit of the network is determined.

  In this communication control device, after the network integration is completed, each time the transmitter transmits a test signal, and the shortening circuit changes the rising or falling time of the communication signal waveform step by step, the determination unit establishes communication. By determining whether or not, the rise or fall time near the limit at which network communication is established is determined. In this process, if the conditions for the shortened circuit are first determined when the vehicle network is determined, it is possible to use one constant circuit that has been previously determined for mass production vehicles. .

  A communication system according to the present invention includes the communication control device according to the present invention and a plurality of networks connected to the communication control device.

  According to the communication control device according to the present invention, the ECU having the shortening circuit can be adjusted so that ringing is greatly generated, for example, functions can be unified with respect to the communication control device connected to a plurality of buses, Since no dummy unit is required, the parts cost does not increase, and the monitoring function can be unified, so the part cost and software cost can be reduced, and it is possible to detect that unauthorized electronic devices are connected to the communication system, and the communication system is external. Therefore, it is possible to realize a communication control apparatus that is unlikely to fall into a communication disabled state due to the influence of the above.

  According to the communication system according to the present invention, an ECU having a shortening circuit can be adjusted so that ringing is greatly generated. For example, functions can be unified with respect to communication control devices connected to a plurality of buses. Since no unit is required, the cost of parts does not increase, and the monitoring function can be unified, so that the cost of parts and software can be reduced, and it is possible to detect that unauthorized electronic devices are connected to the communication system. A communication system that does not easily fall into a communication disabled state can be realized.

It is a block diagram which shows schematic structure of the gateway which is embodiment of the communication control apparatus which concerns on this invention, and a communication system, and a communication system. It is a block diagram which shows the structural example of a gateway. It is a circuit diagram which shows the structural example of a shortening circuit. It is a wave form diagram which shows the example of the waveform of ringing. It is a flowchart which shows the example of the procedure which sets a shortening circuit. It is a flowchart which shows the example of operation | movement of a gateway. It is a circuit diagram which shows the other structural example of a shortening circuit.

  Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.

FIG. 1 is a block diagram showing a schematic configuration of a gateway and a communication system which are embodiments of a communication control apparatus and a communication system according to the present invention.
This communication system includes a large number of ECUs (Electronic Control Units) 1a to 1h and end ECUs 2a to 2d mounted on a vehicle, and three main lines 3a of three networks each constituted by these ECUs 1a to 1h and end ECUs 2a to 2d. , 3b, 3c are connected to a gateway (communication control device) 5.

The terminal ECU 2a is connected to one end of a trunk line 3a having a pair of communication lines, and the terminal ECU 2b is connected to the other end of the trunk line 3a.
The ECU 1a is connected to a branch line 4a branched from the main line 3a, the ECU 1b is connected to a branch line 4b branched from the main line 3a, and the ECU 1c is connected to a branch line 4c branched from the main line 3a. The gateway 5 is connected to a branch line 4i branched from the trunk line 3a.
The branch lines 4a, 4b, 4c, 4i have a pair of communication lines.

The terminal ECU 2c is connected to the other end of the trunk line 3b having a pair of communication lines.
The ECU 1d is connected to a branch line 4d branched from the main line 3b, and the ECU 1e is connected to a branch line 4e branched from the main line 3b. One end of the trunk line 3b is connected to the gateway 5.
The branch lines 4d and 4e have a pair of communication lines.

The terminal ECU 2d is connected to the other end of the trunk line 3c having a pair of communication lines.
The ECU 1f is connected to a branch line 4f branched from the main line 3c, the ECU 1g is connected to a branch line 4g branched from the main line 3c, and the ECU 1h is connected to a branch line 4h branched from the main line 3c. One end of the trunk line 3 c is connected to the gateway 5.
The branch lines 4f, 4g, and 4h have a pair of communication lines.
Here, the trunk lines 3a to 3c and the branch lines 4a to 4i are twisted pair cables having characteristic impedances possessed by a CAN (Controller Area Network) bus.

FIG. 2 is a block diagram illustrating a configuration example of the gateway 5.
The gateway 5 is constituted by a microcomputer, and is interconnected by a bus 19, a control unit 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, an input unit 14, an output unit 15, and drivers 16a and 16b. , 16c, shortening circuits 22a, 22b, 22c, connection circuits 23a, 23b, 23c, a drive circuit 24, and the like.
The control unit 11 is configured by using an arithmetic processing device such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and reads various control programs stored in the ROM 12 to execute various control processes. I do.

  The ROM 12 is configured by a nonvolatile memory element such as an EEPROM (Electrically Erasable Programmable ROM) or flash memory, for example, and includes a control program executed by the control unit 11 and information necessary for processing performed by the control unit 11. Stored in advance. The RAM 13 is configured by a memory element such as SRAM (Static RAM) or DRAM (Dynamic RAM), for example, information created by the processing of the control unit 11, information transmitted to and received from other ECUs, and the like Is memorized.

  The input unit 14 receives, for example, a signal from an input device such as an operation switch arranged in the vehicle, and controls the information obtained by performing processing such as sampling of the input signal or A / D conversion. 11 is given. For example, the display unit 18 is connected to the output unit 15 and outputs a display signal in accordance with an instruction from the control unit 11.

The drivers 16a, 16b, and 16c transmit and receive in order to mediate communication between the ECUs 1a to 1h and the terminal ECUs 2a to 2d connected to networks having different CAN protocols, and branch lines 4i are connected through connection circuits 23a, 23b, and 23c, respectively. , Main lines 3b and 3c. The drivers 16a, 16b, and 16c convert the transmission information given from the control unit 11 into transmission data (frames) according to the CAN protocol of the destination network, and send the data to the transmission units 20a, 20b, and 20c. give.
The transmission units 20a, 20b, and 20c each output a signal to the branch line 4i and the trunk lines 3b and 3c according to the value (0 (dominant) or 1 (recessive)) of each bit of the given transmission data.

  The transmission units 20a, 20b, and 20c output differential signals to the branch lines 4i and the trunk lines 3b and 3c that are connected via the connection circuits 23a, 23b, and 23c, respectively. When transmitting the dominant signal, the transmission units 20a, 20b, and 20c output a differential signal in which the potential difference between the pair of communication lines of the branch line 4i and the trunk lines 3b and 3c is 2 V, and transmit a recessive signal. When this is done, a differential signal with the potential difference of 0V is output.

  The drivers 16a, 16b, and 16c detect the signal levels of the branch lines 4i and the trunk lines 3b and 3c, so that the signals transmitted on the branch lines 4i, the trunk lines 3b and 3c correspond to either dominant or recessive signals. It has receiving part 21a, 21b, 21c which determines whether it is. The receiving units 21a, 21b, and 21c receive data in which each bit is represented by dominant or recessive according to the CAN protocol of each receiving destination network. The signal level of the branch line 4i and the trunk lines 3b and 3c is a potential difference between a pair of communication lines included in the branch line 4i and the trunk lines 3b and 3c. The drivers 16a, 16b, and 16c give the data received by the receiving units 21a, 21b, and 21c to the control unit 11, respectively.

The connection circuits 23a, 23b, and 23c are interposed in the branch lines 4i and the trunk lines 3b and 3c, respectively, and are configured to suppress reflected waves due to signals input from the branch lines 4i and the trunk lines 3b and 3c to the drivers 16a, 16b, and 16c. Has been.
The drivers 16a, 16b, and 16c are connected to shortening circuits 22a, 22b, and 22c that shorten the rise or fall time of the signal waveform on the communication line to near the limit at which communication is established. Here, as the drivers 16a, 16b, 16c, a driver having a terminal for controlling the falling edge of the waveform, for example, any one of NXP PC82C250, TI sn65hd230, AD ADM3051, etc. is used. The terminal and the shortening circuits 22a, 22b, and 22c are connected.

FIG. 3 is a circuit diagram showing a configuration example of the shortening circuit 22 (22a, 22b, 22c).
The shortening circuit 22 includes resistors R1, R2, and R3 for connecting the Rs terminal and the ground terminal of the driver 16 (16a, 16b, and 16c) in parallel, and a switch S1 that connects the resistor R1 between the Rs terminal and the ground terminal. And a switch S2 that connects the resistor R2 in parallel with the resistor R1, and a switch S3 that connects the resistor R3 in parallel with the resistors R1 and R2. The switches S1, S2, and S3 are on / off controlled by the drive circuit 24, respectively.

The rise or fall time of the signal waveform on the communication line becomes longer and shorter according to the magnitude of the impedance between the communication lines, and when it becomes shorter, ringing due to vibration accompanying overshoot and undershoot increases.
Here, for example, as shown in FIG. 1, when an unauthorized wireless device (or electronic device) 6 is connected to the main line 3b, the impedance between the communication lines becomes small.

Therefore, if the shortening circuit 22a, 22b, 22c shortens the rising or falling time of the signal waveform on the communication line to near the limit where communication is established, when the unauthorized wireless device 6 is connected to the trunk line 3b, It can be estimated that the ringing of the connected network (trunk line 3b) becomes large and communication becomes impossible and an unauthorized wireless device 6 is connected.
In other words, when the electronic device is further connected to the communication line, the rising or falling time of the signal waveform is shortened so that the ringing waveform reaches the 0/1 signal threshold and communication becomes impossible.

For example, when the switch S1 is turned on, the resistor R1 is connected in parallel to the driver 16, but if the impedance between the communication lines is still large, the ringing waveform is small as shown in the waveform diagram of FIG. 4A.
When the switch S2 is further turned on, the resistors R1 and R2 are connected in parallel to the driver 16, but the impedance between the communication lines is further reduced. As shown in the waveform diagram of FIG. It grows up to the vicinity.

When the switch S3 is further turned on, the resistors R1, R2, and R3 are connected in parallel to the driver 16, and the impedance between the communication lines is further reduced. As shown in the waveform diagram of FIG. 4C, the ringing waveform is a signal threshold value. To reach the communication disabled state.
In this case, when the switch S3 is turned off, the resistors R1 and R2 are connected in parallel to the driver 16, and the impedance between the communication lines is slightly increased. As shown in the waveform diagram of FIG. 4B, the ringing waveform is the signal waveform. It returns to a state slightly smaller than the threshold value.

Therefore, if communication is established when the switches S1 and S2 are turned on, it can be estimated that the unauthorized wireless device 6 is not connected. If communication is not established, the unauthorized wireless device 6 is connected. Can be estimated.
Therefore, at the time of communication, the switches S1, S2, and S3 are turned off, and the switches S1 and S2 are turned on at a predetermined time, for example, when the vehicle engine is started, and the transmission unit 20 (20a, 20b, 20c). ) To output a test signal so that the receiving unit 21 (21a, 21b, 21c) determines whether or not the test signal can be received to the extent that communication is established.

Hereinafter, a procedure for setting the shortening circuits 22a, 22b, and 22c of the ECU having such a configuration will be described with reference to the flowchart of FIG.
When the gateway 5 is assembled into the vehicle and the network is configured and connected to the network (S1), the gateway 5 starts transmitting a test signal from the transmitting unit (transmitting unit) 20 (S3). Next, the gateway 5 causes the driver 16 to turn on (connect) the switch S1 (S5), and can the reception unit (determination unit) 21 receive the test signal to the extent that communication is established (whether communication is established). It is determined whether or not (S7).

When the reception unit 21 determines that communication is established (S7), the gateway 5 causes the driver 16 to turn on (connect) the switch S2 (S9), and determines whether communication is established in the reception unit 21. (S11).
When the reception unit 21 determines that communication is established (S11), the gateway 5 causes the driver 16 to turn on (connect) the switch S3 (S13), and determines whether communication is established in the reception unit 21. (S15).

When the reception unit 21 determines that communication is established (S15), the gateway 5 stores the connection state of the switches S1, S2, and S3 in the RAM 13 or the ROM 12 when it is determined that communication is established (S17). If the switches S1, S2, and S3 are connected, the impedance between the communication lines is sufficiently small, and it can be assumed that the rise or fall time of the communication signal waveform has reached the vicinity where the communication is established. .
Next, the gateway 5 causes the driver 16 to release the connection state of the switches S1, S2, and S3 (S19), stops the test signal transmission from the transmission unit 20, and ends (S21).

When the reception unit 21 determines that communication is not established (S7), the gateway 5 causes the driver 16 to turn off the switch S1 (disconnect) (S23) and turn off the switch S1 (disconnect) The connection state of the subsequent switches S1, S2, and S3 is stored in the RAM 13 or ROM 12 (S17).
When the reception unit 21 determines that communication is not established (S11), the gateway 5 causes the driver 16 to turn off the switch S2 (disconnect) (S25) and turn off the switch S2 (disconnect). The connection state of the switches S1, S2 and S3 in the network is stored in the RAM 13 or the ROM 12 (S17).

  When the ECU 21 determines that communication is not established (S15), the ECU causes the driver 16 to turn off (disconnect) the switch S3 (S27) and turn off the switch S3 (disconnect). The connection state of the switches S1, S2, S3 of the network is stored in the RAM 13 or the ROM 12 (S17).

The operation of the gateway 5 will be described below with reference to the flowchart of FIG.
The gateway 5 satisfies a condition for starting a determination as to whether an unauthorized electronic device is connected to the communication system, such as when communication is not performed in the communication system and the vehicle engine is started. Then (S31), the first network is selected according to a predetermined order (S33). Next, the gateway 5 reads the connection state of the switches S1, S2, and S3 of the network stored in the RAM 13 or the ROM 12 (S35).

Next, the gateway 5 turns on (connects) the switches S1, S2, and S3 according to the read connection state (S37), and starts transmitting a test signal from the transmission unit 20 to the network (S39). At this time, the switches S1, S2, and S3 may all be off (S37).
Next, the gateway 5 causes the receiving unit 21 to determine whether or not the test signal can be received to the extent that communication is established (communication is established) (S41).

  When the reception unit 21 determines that communication is established (S41), the gateway 5 causes the driver 16 to release the connection state of the switches S1, S2, and S3 (S43), and stops the test signal transmission from the transmission unit 20 (S45). Next, the gateway 5 ends the determination if the determination as to whether or not an unauthorized electronic device is connected is completed for all networks (S47).

The gateway 5 selects the next network (S33) if the determination as to whether or not an unauthorized electronic device is connected to all the networks has not been completed (S47).
When the reception unit 21 determines that communication is not established (S41), the gateway 5 displays on the display (display unit) 18 that the network cannot be communicated (S49), and ends the determination.

It should be noted that the procedure for setting the ECU shortening circuit 22 (22a, 22b, 22c) as described above (FIG. 5) shortens the rise or fall time of the signal waveform on the communication line to near the limit at which communication is established. If the connection state of the circuit 22 is set, the mass circuit can simplify the shortening circuit 22 as shown in FIG. 7 and reduce the component cost.
The simplified shortening circuit 22d includes a resistor R4 for connecting the Rs terminal and the ground terminal of the driver 16, a resistor R5 for connecting the resistor R4 in parallel, and a switch S4 for connecting the resistor R5 to the resistor R4 in parallel. I have. The switch S4 is ON / OFF controlled by the drive circuit 24. Note that the resistor R4 may be unnecessary depending on the set connection state.

  The embodiments disclosed herein are illustrative in all respects and should not be considered as restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of claims for patent, and is intended to include all modifications within the scope and meaning equivalent to the scope of claims for patent.

1a to 1h ECU (communication device)
2a to 2d End ECU (communication device)
3, 3a-3c Trunk line 4a-4i Branch line 5 Gateway (communication control device)
6 Unauthorized wireless devices (electronic devices)
16, 16a to 16c Driver 18 Display (display unit)
19 Bus 20, 20a-20c Transmitter (transmitter)
21, 21a-21c Receiving part (determination part)
22, 22a-22d shortening circuit 23, 23a-23c connection circuit R1, R2, R3, R4, R5 resistance S1, S2, S3, S4 switch

Claims (5)

A trunk line having a pair of communication lines; and a plurality of communication devices connected to the pair of communication lines, wherein a plurality of networks each communicating with the plurality of communication devices are connected, and communication between the networks is mediated In the communication control device
A shortening circuit that shortens the rise or fall time of a communication signal waveform on the communication line in the network to near the limit at which communication is established;
A transmitter for transmitting a test signal for determining whether or not communication is established in the network to the communication line at a predetermined time;
A communication unit comprising: a determination unit that determines whether communication is established when the transmission unit transmits a test signal in the network and the shortening circuit is on, for each network. Control device.   The communication control device according to claim 1, wherein the transmission unit is configured to transmit a test signal when not communicating on the trunk line. When the determination unit determines that communication is not established, the determination unit further includes a display unit that displays that communication within the network is impossible,
The communication control device according to claim 1, wherein the shortening circuit is configured to change the rising or falling time stepwise.   After the integration of the network is completed, each time the transmitter transmits a test signal and the shortening circuit changes the rising or falling time step by step, the determination unit determines whether communication is established. The communication control device according to claim 3, wherein the communication control device is configured to determine a rise time or fall time in the vicinity of the limit of the network.   A communication system comprising: the communication control device according to any one of claims 1 to 4; and a plurality of networks connected to the communication control device.

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