JP2011182123A - Communication system, communication apparatus, and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system, communication apparatuses and a communication method, wherein, each communication apparatus is bus-connected separately to two communication lines different from each other, the each communication apparatus is connected separately with two communication apparatuses in one to one manner to form a loop connection, thereby forming a flexible configuration achieving high speed and failure resistance even when the configuration uses existing protocols. <P>SOLUTION: The respective communication apparatuses 1, 2a have different connection sections, respectively, are bus-connected separately to the communication lines 3a, 3b, 3e, and when one of the communication apparatuses breaks down and so on, the connection section which has become incommunicable is replaced by a loopback section. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention can be applied to a configuration using an existing protocol, a high-speed and flexible configuration, even when a part of communication devices break down or a communication device is added to the system. The present invention relates to a communication system, a communication apparatus, and a communication method capable of performing efficient communication without hindrance.

  In recent years, control systems that control a large number of devices and realize various functions as a whole have become widespread. A control device is connected to each device, each control device is provided with a communication means to exchange data with each other, and data obtained from one device is used to control other devices. A communication system for executing control is realized. Such a communication system is used in various fields.

  In particular, in the field of vehicles, traveling control of vehicles is shifting from mechanical control to electrical control. For example, communication systems such as CAN (Controller Area Network), LIN (Local Interconnect Network), and FlexRay (registered trademark) are used in accordance with the immediacy and certainty required for data to be communicated. Has been built. In particular, the LIN protocol is used to transmit and receive data related to control of body-type devices such as doors, lamps, and mirrors, sensor data, and input / output data for loads such as actuators (Non-Patent Document 1). ).

  The functions required of vehicles are increasing and diversifying. This increases the number of devices such as actuators and sensors mounted on the vehicle and the number of control devices that control the devices. However, in the field of vehicles, it is desired to save power and reduce the weight of the entire system in order to improve the fuel efficiency of the vehicle and expand the vehicle interior space. Therefore, wire saving, simplification, and weight reduction of the communication system are desired. Further, in the communication system in the field of vehicles, in particular, when the data to be communicated is used for travel control, when it is used for transmission of operation information in an HMI (Human Machine Interface), immediacy, certainty and safety are required. .

  Patent Document 1 discloses an invention related to an in-vehicle communication system that transmits and receives body information such as a door. In the present invention, the cost of the entire communication system is reduced by using a communication apparatus (communication node) that does not have a data processing device such as a CPU. The communication system disclosed in Patent Document 1 has a configuration in which a plurality of nodes are connected in a bus shape to a ring-shaped multiple communication line to perform communication based on CSMA / CD. By being connected to the bus type, data transmitted from any one of the communication devices can be immediately received by another communication device.

Japanese Patent No. 3298995

LIN Consortium, “LIN Specification Package” (LIN specification), Revision 2.1 freescale, “DSI Bus Standard”, ver.2.02, March 29, 2005, [online], [search August 7, 2009], Internet <URL: http://www.freescale.com/files /analog/doc/support_info/dsibusstandard.pdf> Safe-by-Wire-Plus Consortium, “Automotive Safety Restraints Bus Specification”, ver. 2.0, September 24, 2004, [online], [Search August 7, 2009], Internet <URL: http: / /www.nxp.com/acrobat_download/other/automotive/safe_by_wire_plus.pdf>

  LIN is a single-wire serial bus protocol and is half-duplex communication. In the LIN, one node becomes a master and controls communication with a plurality of other slave nodes. When LIN is applied to control related to opening and closing of a vehicle door, a device such as a door motor or a switch becomes a slave node. Since the doors of the vehicle are on the front and rear sides and the left and right sides of the vehicle, the slave nodes are arranged in a wide range within the vehicle. Since the master node controls communication with the slave node, it is necessary to connect all the slave nodes related to opening and closing of doors to one LIN bus.

  Due to such necessity, the length of the LIN bus is allowed up to 40 meters (Non-Patent Document 1). In order to cope with noise or signal attenuation in a relatively long LIN bus, the bus voltage level is defined from the battery voltage to the GND level. However, this is contrary to the power saving and weight reduction of the entire system.

  The LIN communication is controlled by the master node as described above. All slave nodes connected to the LIN bus transmit data including the response frame for the header frame only when the identification information (ID) included in the header frame transmitted from the master node to the LIN bus indicates itself. Other slave nodes can constantly monitor frames sent to the LIN bus and extract data if necessary. That is, unless the master node transmits the header frame to the LIN bus, the slave node cannot transmit / receive.

  As described above, the number of devices mounted on the vehicle is increasing due to the shift to the electric control of the vehicle. Conventionally, devices such as sensors, switches, and motors are generally connected directly to an ECU (Electronic Controller Unit) that controls them. However, with the recent increase in electronic equipment, wiring with devices connected to the ECU has increased, and the size of connectors has also been increasing. From the viewpoints of downsizing and cost reduction, it is desirable to connect devices such as sensors, switches, and motors to a network such as LIN so that the ECU can efficiently transmit and receive control signals and the like by communicating with each device.

  However, when each device including sensors, switches, and motors is connected to a network, even if a protocol that can realize cost reduction such as LIN is used, if the number of connected devices increases There's a problem. There is a limit to the number of nodes connected to one LIN bus. This is because the communication is hindered by an increase in noise received by the LIN bus, disturbance of the signal waveform, and the like. As a result, when the number of devices increases, it becomes necessary to add a new LIN bus, which hinders cost reduction.

  As in the case of LIN, DSI, ASRB2.0, and the like exist as examples of a single-wire serial bus protocol and a half-duplex communication protocol (Non-Patent Documents 2 and 3). In a system using these protocols, the connection form between the slave nodes is apparently a daisy chain type in which the nodes are connected one to one. This is because, in order to eliminate the need for fixed information as identification information (ID) of each slave node, it is connected in a chain from the master node and has an ID according to the connection order. Each slave node has a connection terminal connected to each of the two communication lines. After giving the ID, the connection terminals are internally connected to form an electrically identical bus. Connect to the bus. Except for the point where the bus branch point is accommodated in the slave node, it is the same as the general bus type connection form.

  Thus, in the master-slave communication in the prior art, the master node and the slave node are all connected to the same long communication line by bus connection. This is because by using the bus connection, it is possible to maintain the function between the remaining nodes as long as there is no problem such as disconnection of the communication line even when some nodes fail. However, in the configuration in which the master node and the slave node are all connected to the same long communication line, it is necessary to use a long distance bus as described above. When the number of devices increases, noise suppression, signal attenuation, etc. The problem remains.

  In the case of a daisy chain type connection configuration, there is no problem such as signal attenuation because a long distance bus is unnecessary. However, when some nodes fail and communication becomes impossible, the function of the entire system stops. As a countermeasure, there is a duplication countermeasure in which nodes are connected by two communication lines, respectively, but this is contrary to wire saving and weight reduction, and hinders cost reduction. In addition, there is a countermeasure to connect the nodes located at the start and end to make a ring type. However, in the case of the ring type, even if a failure occurs, if it is a failure in which any signal can propagate, it is necessary to perform communication between normal nodes at a time when propagation is possible, and the communication speed decreases. Problems such as remain.

  The present invention has been made in view of such circumstances, and each communication device is connected to each of two different communication lines by a bus, and each of the communication devices is connected to each of the two communication devices in a one-to-one ring shape. An object of the present invention is to provide a communication system, a communication apparatus, and a communication method that can realize high speed and fault tolerance even in a configuration using a protocol and can be applied to a flexible configuration.

  A communication system according to a first aspect of the present invention is the communication system in which a plurality of communication devices communicate with each other via a communication line, wherein a part or all of the plurality of communication devices are respectively connected to two different communication lines. Two connection portions for separately connecting the buses are provided, and the other two communication devices are connected to each other by the two connection portions via different communication lines.

  A communication system according to a second aspect of the present invention is a communication system including one master communication device and a plurality of slave communication devices, wherein each communication device is connected and communicated via a communication line. Are partly or entirely provided with two connection parts each connected to two different communication lines by a bus, and are connected to the other two communication devices via different communication lines by the two connection parts, respectively. When the slave communication device receives the information transmitted from the master communication device in one of the two connection units, when the received information corresponds to itself, the slave communication device returns a response corresponding to the information. When information transmitted from one side and received does not correspond to itself, the received information is transferred from the other side.

  In the communication system according to the third invention, each communication device is determined to be abnormal when the determination device determines normality / abnormality of communication with another connected communication device, and the determination device determines that the communication device is abnormal. And a means for disconnecting the connection at the connection unit through communication with the communication device.

  In the communication system according to the fourth aspect of the present invention, the master communication device transmits a specific signal, and each communication device has an upstream side of the connection unit that has received the specific signal among the two connection units, Recognize the other connection as downstream and transfer the data received from the upstream connection from the downstream connection, or send a response to the data received at the upstream connection from the downstream connection When the connection at the upstream connection portion is disconnected, the other connection portion recognized as the downstream side is re-recognized as the upstream connection portion, and the upstream side When data is received from the re-recognized connection unit, a response is transmitted from the upstream connection unit.

  In the communication system according to the fifth aspect of the present invention, the connection unit of each communication device has a transmission / reception terminal, and transmits a signal input to the transmission terminal to the communication line and receives a signal received from the communication line. A transceiver that performs output from the terminal, a transmission / reception terminal of the transceiver, each having a transmission / reception terminal connected via a switch, and a transmission / reception unit that inputs and outputs a signal to be transmitted to and received from the transceiver, The switch is configured to be capable of switching between connection of a transmission / reception terminal of the transmission / reception unit to a transceiver and a short circuit between the transmission / reception terminals.

  In the communication system according to a sixth aspect of the present invention, when each of the communication devices determines that the determination unit is abnormal, the communication device issues a switching instruction to a short circuit between the transmission / reception terminals of the transmission / reception unit to the connection unit via the communication determined to be abnormal. It has the means to output, It is characterized by the above-mentioned.

  In a communication system according to a seventh aspect of the present invention, the connection unit of the communication device includes a monitoring unit that monitors the output of the reception terminal of the transceiver, and the monitoring unit is configured to return the connection from the outside that has been set in advance. And a means for detecting a signal corresponding to.

  In a communication system according to an eighth aspect of the present invention, the master communication device includes a determination unit that determines normality / abnormality of communication in another communication device, and the determination unit has a connection unit through communication determined to be abnormal. An instruction for switching to a short circuit between the transmitting and receiving units of the connection unit is transmitted to the apparatus.

  In the communication system according to the ninth aspect of the present invention, any two connectable communication devices among the communication devices are communication based on a communication protocol different from communication between other communication devices or communication between other communication devices. The communication is performed through different communication media.

  A communication system according to a tenth aspect is characterized in that each communication device communicates based on a LIN (Local Interconnect Network).

  A communication device according to an eleventh aspect of the present invention includes two connection portions that are separately bus-connected to two different communication lines. Each of the two connection portions has a transmission / reception terminal and is input to the transmission terminal. A transceiver that transmits signals to a communication line and outputs a signal received from the communication line from a reception terminal, and a transmission / reception terminal connected to the transceiver via a switch. And a transmission / reception unit for inputting / outputting a signal to be transmitted / received to / from the transceiver, and the switch is configured to be able to switch between connection of the transmission / reception terminal of the transmission / reception unit to the transceiver and a short circuit between the transmission / reception terminals. It is characterized by being.

  According to a twelfth aspect of the present invention, there is provided a communication apparatus according to a twelfth aspect, wherein: means for determining normality / abnormality of communication in the two connection portions; And a means for outputting an instruction for switching to a short circuit between the terminals.

A communication method according to a thirteenth invention is a communication system including one master communication device and a slave communication device, in which each communication device communicates with another communication device via a communication line.
A part or all of each communication device includes two connection portions that are respectively connected to two different communication lines by buses, and the other two communication devices are connected via different communication lines depending on the two connection portions. When the slave communication device receives information transmitted from the master communication device in one of the two connection units, the received information corresponds to itself. A response corresponding to the information is transmitted from the other, and when the received information does not correspond to itself, the received information is transferred from the other, and each communication device communicates with other connected communication devices. When normal / abnormal is determined, and it is determined that there is an abnormality, the connection at the connection portion with the communication line through communication with another communication device determined to be abnormal is disconnected, and information is obtained at a connection portion different from the connection portion. If received, disconnected Wherein the turn back information in connection part.

In the first invention and the second invention, each of the plurality of communication devices is connected to two different communication devices on a one-to-one basis via different communication lines. Since both are connected to two communication devices, the entire system is connected in a ring shape. However, since each communication device is connected to one communication line by a bus at the connection unit, transmission and reception can be performed independently on one communication line and the other communication line. In addition, communication devices of the entire system are not connected to one communication line by bus, but only a minimum of two communication devices are connected by bus. As a result, it is only necessary to route communication lines only in necessary portions, and noise, attenuation, and signal degradation are reduced. In addition, since each communication device is connected by bus, transmission / reception is possible at each connection unit.
Note that another communication device may be separately connected to the communication line to which the two communication devices are connected. It is possible to flexibly cope with a case where a communication device is newly connected according to an additional function of the communication system.

Particularly in the second invention, one of the plurality of communication devices is a master communication device, and the other communication devices communicate as slave communication devices. Both the master communication device and the slave communication device can communicate with the other two communication devices via the two connection portions as in the first invention. In the second invention, when the information transmitted by the master communication device is transmitted to the slave communication device, and the slave communication device receives one of the two connection units, the information is information corresponding to itself. If so, the response is transferred from the other side. That is, the master communication device serves as a transmission / reception base between the communication devices connected in a ring shape, and each slave communication device is controlled to transfer the received information to the other.
As a result, it is possible to increase the speed compared to the case where each communication device returns and transmits information between the communication devices connected in a ring when the information transmitted from the master communication device can be received again by the master communication device. It is also possible to confirm that any one-to-one connection is normal.

  In the third and thirteenth inventions, each communication device that is basically connected in a one-to-one relationship with another communication device determines normality / abnormality of communication with the other communication device, and is determined to be abnormal. It is possible to disconnect from the communication line at the connection unit via the communication, avoid abnormal transmission from other communication devices, and avoid influence on other communication devices due to abnormal transmission from itself. Even in the case of disconnection, each communication device is connected to the two communication devices in a ring shape, so that communication with other communication devices can be continued through the other connection unit. That is, even if the communication device that has been disconnected is disconnected from the annular connection, the communication device can continuously communicate by communication at the connection portion on the opposite side, and fault tolerance is improved.

  In the fourth invention, each communication device recognizes the two connecting portions as the upstream side or the downstream side, and basically performs communication control so as to preferentially transmit and receive data from the upstream side to the downstream side. Is possible. The upstream and downstream recognition methods include, for example, a method of recognizing a connection unit that has received specific information transmitted by the master communication device as an upstream connection unit when the master communication device exists. is there. Each communication device disconnects the connection at the upstream connection portion when the communication with the other communication device via the upstream connection portion is abnormal, and recognizes the other connection portion as the upstream side thereafter. Transmission / reception can be continued. At this time, the transmission / reception control is maintained as it is because the disconnected connection portion is configured to return information internally.

In the fifth and eleventh aspects of the invention, each of the two connection portions provided in the communication device has a transceiver terminal that realizes transmission / reception in the physical layer to the communication line, and a transceiver transmission / reception terminal. Realizes switching between the transceiver and transmitter / receiver between the transceiver and the transmitter / receiver that inputs and outputs signals to be transmitted / received, and disconnects the transceiver from the transmitter / receiver and switches between the transmitter and receiver terminals of the transmitter / receiver A switch is provided.
As a result, when the transmission / reception unit itself is switched so that the transmission terminal and the reception terminal are connected, the signal output for transmission by the transmission / reception unit is received by the return transmission / reception unit and correctly transmitted / received to the communication line. It is possible to realize the same operation as when Thereby, it is not necessary to change the function of the transmission / reception unit to a special specification.

  In 6th invention and 12th invention, when a communication apparatus judges that communication with other communication apparatuses is abnormal, it short-circuits the terminal for transmission / reception of a transmission / reception part to its connection part via the communication judged to be the said abnormality Instruct to switch. It can be performed in response to determining that the switching of the switch is abnormal.

In the seventh invention, a monitoring unit for monitoring the output of the receiving terminal of the transceiver included in the connection unit is provided. The transceiver receives the signal transmitted to the communication line and outputs it to the receiving terminal even if the communication device is disconnected from the communication line and short-circuited. continuing. By monitoring the output with the monitoring unit, it is possible to return to normal, for example, when an activation signal or the like can be received from the communication line, detect this and restart the connection between the transmission and reception terminals.
By providing the monitoring unit separately from the transmission / reception unit, monitoring can be continued without affecting the transmission / reception unit even when an excessive signal is transmitted to the communication line due to some abnormality.

  In the eighth invention, one master communication device included in the communication system determines which of the other communication devices an abnormality has occurred, and the master communication device disconnects from the communication device determined to be abnormal. A switching instruction for instructing is transmitted to another communication device by communication. Since communication abnormalities occur in various situations, even if each communication device cannot determine, it can be disconnected if the master communication device comprehensively determines abnormalities, and safety is improved.

  In the ninth invention, in any one of the first to eighth inventions, any two communication devices of each communication device constituting the communication system are connected to one communication line different from the other to realize communication. Therefore, communication via the one communication line does not interfere with communication via the other communication line. Therefore, communication between any two communication devices can be performed using a communication protocol different from the others, or via a different communication medium, and further, the communication medium and the communication protocol can be performed using different methods. Thereby, a communication system can respond to a flexible structure. For example, only a communication between some communication apparatuses can be configured to be able to transmit and receive at best effort. In addition, it is possible to improve the safety of certainty by adopting a configuration in which communication can be ensured only for communication between some communication devices, for example, by communication using a time division multiplexing method.

  In the tenth aspect of the invention, communication is basically performed between the communication devices based on LIN, which is a single-wire serial bus protocol. As a result, the configuration of the transmission / reception unit of the connection unit can use resources adapted to the existing LIN, and the communication device does not need to have a special specification.

  According to the present invention, each communication device is separately connected to two different communication lines by a bus, and each communication device is connected to the two communication devices in a one-to-one manner so that a long communication line is not necessary and necessary. All you need to do is place a plan. In addition, since there are two communication devices connected to each communication line by bus, noise, attenuation, and signal deterioration in the communication line are reduced. Since transmission / reception on each communication line is possible independently, high speed can be expected. Furthermore, even when a failure occurs in some communication devices, communication can be continued by disconnecting. As described above, even a configuration using an existing protocol can be applied to a flexible configuration such that the speed and fault tolerance can be improved and the protocol in each communication line can be changed.

It is a block diagram which shows the structure of the vehicle-mounted communication system in this Embodiment. It is a block diagram which shows the internal structure of the communication apparatus which comprises the vehicle-mounted communication system of this Embodiment. It is explanatory drawing which shows the example of the content of the wake-up frame transmitted from the communication apparatus which is a master node in the vehicle-mounted communication system in this Embodiment. It is a flowchart which shows an example of the reception process of the WKUP_m frame by the transmission / reception control part of the communication apparatus which is a slave node. FIG. 10 is a sequence diagram illustrating a process in which a WKUP_m frame is transmitted from a master node to a slave node. It is a sequence diagram which shows the process in which connection is switched by each communication apparatus when abnormality arises in communication with a vehicle-mounted communication system. It is explanatory drawing which shows notionally the logical connection relationship which changes with the process of the communication apparatus in this Embodiment. It is a sequence diagram which shows the process in which connection is switched by each communication apparatus when the operation abnormality of one communication apparatus generate | occur | produces in a vehicle-mounted communication system. It is a sequence diagram which shows the process in which connection is switched by each communication apparatus, when the communication apparatus which operation | movement abnormality generate | occur | produced in the vehicle-mounted communication system returns. It is a block diagram at the time of making communication between the communication apparatuses of a vehicle-mounted communication system into a different communication protocol.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof. In the embodiment described below, a case where the communication system according to the present invention is applied to an in-vehicle communication system mounted on a vehicle will be described as an example.

  FIG. 1 is a configuration diagram showing the configuration of the in-vehicle communication system in the present embodiment. The in-vehicle communication system in the present embodiment connects the communication device 1 that is a master node, the communication devices 2a, 2b, 2c, and 2d that are slave nodes, and the communication devices 1, 2a, 2b, 2c, and 2d. It includes communication lines 3a, 3b, 3c, 3d, and 3e.

  Each of the communication devices 1, 2a, 2b, 2c, 2d is configured to have two connection portions. The communication device 1 is connected to the different communication lines 3e and 3a in two connection portions 11 and 12 in a bus type. The communication device 2a is connected to the communication line 3a and the communication line 3b by buses at the connection portions 21a and 22a. The communication device 2b is connected to the communication line 3b and the communication line 3c by buses at the connection portions 21b and 22b. The communication device 2c is bus-connected to the communication line 3c and the communication line 3d by connection portions 21c and 22c. The communication device 2d is bus-connected to the communication line 3d and the communication line 3e by connection portions 21d and 22d.

  The communication device 2a communicates one-to-one with the communication device 1 through the communication line 3a via the connection unit 21a, and communicates one-to-one with the communication device 2b through the communication line 3b through the connection unit 22a. To do. Note that communication via the communication line 3a and the communication line 3b is performed using the LIN protocol.

  Similarly, the communication device 1 communicates with the communication device 2a and the communication device 2d on a one-to-one basis via the communication line 3a and the communication line 3e, respectively. The communication device 2b also communicates with the communication device 2a and the communication device 2c on a one-to-one basis via the communication line 3b and the communication line 3c, respectively. The communication device 2c also communicates with the communication device 2b and the communication device 2d on a one-to-one basis via the communication line 3c and the communication line 3d, respectively. The communication device 2d also performs one-to-one communication with the communication device 2c and the communication device 1 via the communication line 3d and the communication line 3e, respectively.

  As shown in FIG. 1, each of the communication devices 1, 2a, 2b, 2c, and 2d is connected to the communication lines 3a, 3b, 3c, 3d, and 3e, respectively, but two different like the daisy chain type. There is a one-to-one connection with the communication device. Further, the communication device 1 as a master node is connected in a one-to-one daisy chain type in the order of the communication device 2a, the communication device 2b, the communication device 2c, and the communication device 2d, and the last communication device 2d is a master node. A communication apparatus 1 is also connected to form a ring type connection. As a result, the number of communication devices connected to each of the communication lines 3a, 3b, 3c, 3d, and 3e is two each in the case of FIG. 1, and the communication lines 3a, 3b, 3c, 3d, and 3e are connected. The signal transmitted and received in a stable manner is propagated in a waveform with little deterioration. In addition, since the communication lines 3a, 3b, 3c, 3d, and 3e are connected on a one-to-one basis, it is possible to efficiently route each of them. In addition, the communication lines 3a, 3b, 3c, and 3d are connected one-to-one, and the communication devices 1, 2a, 2b, 2c, and 2d are connected to the communication lines 3a, 3b, 3c, 3d, and 3e, respectively. Therefore, the communication devices can communicate simultaneously. By using the configuration shown in FIG. 1 rather than a configuration in which a master node and a plurality of slave nodes are all bus-connected to one communication line, communication efficiency can be improved without collision of data transmission. In addition, since communication is possible simultaneously on each communication line, the communication speed of the entire system can be increased as a result.

  The communication device 1 that is a master node is connected to the communication line 4 in addition to the communication lines 3a and 3e that are LIN networks. The communication line 4 is a network of different communication protocols, for example, CAN and FlexRay (registered trademark). The communication device 1 can transmit and receive with other communication devices having different communication protocols.

  FIG. 2 is a configuration diagram showing an internal configuration of the communication devices 1 and 2a constituting the in-vehicle communication system of the present embodiment. Since the internal configurations of the communication devices 2b, 2c, and 2d are the same as the internal configuration of the communication device 2a, illustration and detailed description thereof are omitted.

  The communication device 1 includes a transmission / reception control unit 10 that controls transmission / reception of data via the communication lines 3a and 3e, two connection units 11 and 12, and a transmission / reception control unit that controls transmission / reception of data via the communication line 4. 13 and a relay unit 14 that realizes relay of data transmission / reception between the communication lines 3a and 3e and the communication line 4.

  The transmission / reception control unit 10 accepts data provided from the relay unit 14 or other components (not shown), determines which of the two different connection units 11 and 12 should transmit / receive, and two different connection units 11. , 12 is determined whether or not to be disconnected. The transmission / reception control unit 10 is configured in hardware to perform the above-described processing in advance. Note that processing may be performed by software using a microcomputer.

  One connection unit 11 included in the communication device 1 includes a first transmission / reception unit 111, a bus switching unit 112, and a first transceiver 113. Similarly, the other connection unit 12 includes a second transmission / reception unit 121, a bus switching unit 122, and a second transceiver 123.

  Both the connection units 11 and 12 are connected to the transmission / reception control unit 10 by the first transmission / reception unit 111 and the second transmission / reception unit 121. The first transmission / reception unit 111 receives a data signal to be given to the first transceiver 113 to be transmitted to the communication line 3e from the transmission / reception control unit 10, and the data signal received by the first transceiver 113 from the communication line 3e to the transmission / reception control unit 10. Deliver. The first transmission / reception unit 111 has a transmission terminal Tx that outputs the received data signal to be transmitted to the first transceiver 113 as a signal suitable for the LIN protocol. The first transmission / reception unit 111 has a reception terminal Rx for inputting a signal received by the first transceiver 113, and delivers the received signal to the transmission / reception control unit 10. The second transmission / reception unit 121 of the connection unit 12 is also connected with the same configuration as the second transceiver 123.

  Each of the first transceiver 113 and the second transceiver 123 realizes transmission / reception of signals on the communication line 3e and the communication line 3a in the physical layer based on LIN. Each of the first transceiver 113 and the second transceiver 123 has a transmission terminal Tx and a reception terminal Rx, inputs a signal representing data to be transmitted at the transmission terminal Tx, and transmits the communication line 3e or the communication line 3a. From the receiving terminal Rx.

  The bus switching unit 112 is between the transmission terminal Tx of the first transmission / reception unit 111 and the transmission terminal Tx of the first transceiver, and between the reception terminal Rx of the first transmission / reception unit 111 and the reception terminal Rx of the first transceiver. And the connection (short circuit) between the transmission terminal Tx of the first transmission / reception unit 111 and the reception terminal Rx of the first transmission / reception unit 111 are switched. During normal operation, that is, while all the communication devices 1, 2a, 2b, 2c, and 2d constituting the in-vehicle communication system are normally transmitting and receiving, the transmission terminal Tx of the first transmission / reception unit 111 and the first transceiver Between the transmission terminal Tx, the reception terminal Rx of the first transceiver 111 and the reception terminal Rx of the first transceiver are respectively connected. The bus switching unit 122 of the connection unit 12 is configured similarly.

  The transmission / reception control unit 10 of the communication device 1 is abnormally transmitted when, for example, transmission / reception with the communication device 2d via the communication line 3e is abnormal and abnormal transmission is performed from the communication device 2d to the communication line 3e. When the connection unit 11 is disconnected from the communication line 3e so as not to receive data, the transmission terminal Tx of the first transmission / reception unit 111 and the reception terminal Rx of the first transmission / reception unit 111 are connected to the bus switching unit 112 of the connection unit. Is instructed to be connected (short circuit). Specifically, the transmission / reception control unit 10 outputs a switching instruction signal to the bus switching unit 112. As a result, the transmission terminal Tx of the first transmission / reception unit 111 and the reception terminal Rx of the first transmission / reception unit 111 are connected (short-circuited), and the connection unit 11 is in a loopback state. In this way, each of the connection units 11 and 12 can be set in a loopback state, and the communication prosecution is completely separated and isolated from the communication line 3e or the communication line 3a when the communication partner is out of order. It becomes possible. Therefore, there is no influence from a failure node that performs abnormal transmission. In addition, since the transmission / reception unit 111 of the connection unit 11 can input a signal output from the transmission terminal Tx through the reception terminal Rx for transmission, the transmission / reception processing is connected to the communication line 3e via the first transceiver 113. The process can be maintained as it is. Therefore, the first transmission / reception unit 111 can use an existing one without defining a control specification separately.

  The transmission / reception control unit 13 realizes communication via the communication line 4. The relay unit 14 determines whether or not the data is to be relayed to the communication devices 2a, 2b, 2c, and 2d from header information attached to data received via the communication line 4 received from the transmission / reception control unit 13. If it is determined that the data is to be relayed, the received data is given to the transmission / reception control unit 10. Conversely, the data received from the transmission / reception control unit 10 is similarly determined whether it is data to be relayed to another device (not shown) connected via the communication line 4, and is determined to be data to be relayed. If received, the received data is passed to the transmission / reception control unit 13.

  As with the internal configuration of the communication device 1, the communication device 2a that is a slave node includes a transmission / reception control unit 20a, two connection units 21a and 22a, and a monitoring unit 23a that monitors signals from the communication lines 3a and 3b. Including.

  The transmission / reception control unit 20a determines whether or not the data signal received from one of the two connection units 21a and 22a should be transmitted from the other, and whether or not one of the two different connection units 21a and 22a should be disconnected. Make a decision. In addition, when a data signal addressed to itself is received from one side, a process of giving the data to another constituent unit (not shown) is performed. Furthermore, the data given from the component part which is not shown in figure are received, and the process made to transmit from either of two different connection parts 21a and 22a is performed. The transmission / reception control unit 20a may be configured in advance to perform processing as described above, or may be configured to perform processing using software using a microcomputer.

  In the present embodiment, the transmission / reception control unit 20a and the connection units 21a and 22a perform processing based on a clock signal having a time interval (for example, 1/8) shorter than the time interval per bit in the communication protocol. . For example, the connection unit 21a samples one bit of the signal received from the communication line 3a at the short time interval and sequentially outputs it to the transmission / reception control unit 20a. The transmission / reception control unit 20a is output from the connection unit 21a. Whether the bit is 0 or 1 is determined from the sampling result. When the transmission / reception control unit 20a is a part of one bit of data to be transferred to the other connection unit 22a, the transmission / reception control unit 20a performs a process on the part as necessary (invert the bit). This is given to the connecting portion 22a. For example, since the numerical value represented by several bits in the data is decremented by 1 and the data is passed to the connection unit 22a, the connection unit 22a is identified by specifying a bit to be changed and inverting a part corresponding to the bit. Give to. That is, the transmission / reception control unit 20a performs data reception from the connection unit 21a and data transmission through the connection unit 21b almost simultaneously. Accordingly, since the communication lines 3a, 3b, 3c, 3d, and 3e are configured to perform one-to-one communication, for example, data transmission from the communication device 1 to the communication device 2c is several times the frame length. It is possible to avoid the delay.

  Since the two connection portions 21a and 22a included in the communication device 2a are configured in the same manner as the connection portions 11 and 12 included in the communication device 1, corresponding reference numerals are assigned and detailed description thereof is omitted. The communication device 2a transmits / receives data to / from the communication device 1 via the communication line 3a via the connection unit 21a, and transmits / receives data to / from the communication device 2b via the communication line 3b via the connection unit 22a. The two connection units 21a and 22a have bus switching units 212a and 222a, respectively. For example, when there is an abnormality in communication with the communication device 2b connected via the communication line 3b, the transmission / reception control unit 20a outputs a switching instruction to the bus switching unit 222a, short-circuits the transmission terminal Tx and the reception terminal Rx of the second transmission / reception unit of the connection unit 22a to make a loopback state, and disconnects from the communication line 3b. is there.

  As shown in FIG. 2, the switching instruction signal from the transmission / reception control unit 20a to the bus switching unit 212a and the bus switching unit 222a is input to one via a “NOT” circuit. Thereby, the connection by either one is maintained.

  The monitoring unit 23a is configured so that outputs from the reception terminal Rx of the first transceiver 213a of the connection unit 21a and the reception terminal Rx of the second transceiver 223a of the connection unit 22a are branched and input. The monitoring unit 23a monitors signals transmitted from the first transceiver 213a and the second transceiver 223a to the communication lines 3a and 3b. In particular, when any of the connection portions 21a and 22a is disconnected from the communication lines 3a and 3b, when a signal instructing the return of its connection is transmitted to the communication lines 3a and 3b, Detect. For example, when an abnormality occurs in the communication device 2b connected via the communication line 3b by the connection unit 22a and an abnormal transmission is made from the communication device 2b, the communication device 2a has a communication line inside the connection unit 22a. Cut from 3a. Thereafter, when the communication device 2b automatically returns by itself, the monitoring unit 23a detects the return based on data transmitted from the communication device 2b. When detecting the return, the monitoring unit 23a instructs the transmission / reception control unit 20a to output a switching instruction to the bus switching unit 222a. As a result, the connection can be restored.

  The monitoring unit 23a in the present embodiment has a function of detecting and notifying the transmission / reception control unit 20a when an abnormal signal (frame) is transmitted to the communication line 3a or the communication line 3b.

  Communication realized between the communication devices 1, 2a, 2b, 2c, and 2d configured as described above, and processing when a failure occurs in any of the communication devices 2a, 2b, 2c, and 2d that are slave nodes Will be described.

  In the present embodiment, as described above, each communication device 1, 2a, 2b, 2c, 2d performs transmission / reception based on the LIN protocol. In general, the LIN protocol has a configuration in which one master node and a plurality of slave nodes are all connected to the same bus. And when each slave node receives a header containing its own ID for the header (BREAK, SYNC, ID) sent by the master node, it returns a response (DATA, SUM) after that, and other slaves Communication is realized because the node can also receive them simultaneously. In the present embodiment, since the communication devices 1, 2a, 2b, 2c, and 2d are connected to different communication lines 3a, 3b, 3c, 3d, and 3e, it is difficult to communicate with the same processing. Therefore, the communication device 2a, which is a slave node, recognizes one of the two connection portions 21a and 22a as a connection portion on the master side (upstream side) and distinguishes it from the other (downstream side) connection portion. It is like that. Specifically, the transmission / reception control unit 20a stores which is on the upstream side in a built-in memory (not shown). The same applies to the communication devices 2b, 2c and 2d which are other slave nodes.

  A process in which the communication device 2a, which is a slave node, distinguishes between the two connection units 21a and 22a will be described. Since the processing by the communication devices 2b, 2c, and 2d, which are other slave nodes, is the same, detailed description thereof is omitted. First, the communication device 1 as a master node recognizes the connection unit 12 of its two connection units 11 and 12 as a base point as an initial process when the entire system is in a sleep state, that is, in a power-off state ( The wake-up frame is transmitted as a specific signal from the connection unit 12 recognized as the base point.

  FIG. 3 is an explanatory diagram showing an example of the contents of a wake-up frame transmitted from the communication device 1 which is a master node in the in-vehicle communication system according to the present embodiment. FIG. 3 is a time chart showing a wake-up frame transmitted from the communication apparatus 1 and a BREAK frame in the LIN for comparison, and the vertical axis of each time chart shows the signal level.

  FIG. 3 shows an operation (main) clock signal, a sub clock signal, two different wake-up frames, and a BRAKE frame of the communication apparatus 1 from the top. As described above, the operation clock signal is a clock signal having one cycle of a length obtained by dividing the time length of one bit of LIN communication in the communication lines 3a, 3b, 3c, 3d, and 3e by eight. The sub clock signal is a clock signal in which the time length of 1 bit is divided into two, that is, the length of 1/2 bit is one cycle. Based on these clock signals, the transmission / reception control unit 10 and the connection units 11 and 12 operate.

  The BREAK frame shown at the bottom is configured to continue the low level (dominant) for 11 bits or more based on the LIN protocol (13 bits in FIG. 3). The two different wake-up frames are set to lengths that can be distinguished from the BRAKE frame even when the clock error at each node is taken into consideration.

  There are two types of wake-up frames, WKUP_s frame and WKUP_m. The WKUP_s frame is configured such that the dominant lasts for 5 bits. The WKUP_m frame is configured such that a dominant lasts 19 bits. As will be described later, the WKUP_s frame is a frame transmitted from the slave node when the slave node that has been paused returns. Details of the WKUP_s frame will be described later.

  The WKUP_m frame is a wakeup frame that is transmitted as a specific signal from the connection unit 12 that the communication device 1 that is the master node recognizes as a base point. When the communication device 1 transmits a WKUP_m frame from the connection unit 12, the communication devices 2a, 2b, 2c, and 2d that are slave nodes respectively connect the connection unit that receives the WKUP_m frame to the connection unit on the master side (upstream side). Will be recognized later.

  FIG. 4 is a flowchart illustrating an example of WKUP_m frame reception processing by the transmission / reception control unit 20a of the communication device 2a which is a slave node. The flowchart shown in FIG. 4 is an example of processing performed when the entire system is in the sleep state. Note that the processing of the communication devices 2b, 2c, and 2d of the other slave nodes is the same as the processing of the communication device 2a, and detailed description thereof is omitted.

  The communication device 2a performs processing based on the subclock signal when in the sleep state. The transmission / reception control unit 20a initially clears or sets the low level (dominant) count to zero for the signal level of the signal received by the connection unit 21a or the connection unit 22a (step S11). The transmission / reception control unit 20a waits until the signal period of the sub clock signal arrives, that is, until the rising edge of the sub clock signal is detected (step S12). When the signal period comes, the transmission / reception control unit 20a determines whether any of the signal levels received by the connection unit 21a or the connection unit 22a is a low level (step S13).

  If the transmission / reception control unit 20a determines that all signal levels are high (recessive) (S13: NO), the process returns to step S11 to clear the low level count. When the transmission / reception control unit 20a determines that the signal level received by either the connection unit 21a or the connection unit 22a is a low level (S13: YES), the transmission / reception control unit 20a counts the number of low-level bits (step S14).

  Next, the transmission / reception control unit 20a determines whether or not the low level (dominant) is, for example, 19 bits or more based on the number of low level bits (step S15). If the transmission / reception control unit 20a determines that 19 bits or more are not continuous (S15: NO), the process returns to step S12 and waits until the next subclock signal period arrives.

  When the transmission / reception control unit 20a determines that the low level (dominant) is continuous for 19 bits or more (S15: YES), the transmission / reception control unit 20a determines that the WKUP_m frame indicating the activation instruction from the sleep state to the active state is received, and receives the WKUP_frame. The connection part 21a connected to the connection part 12 of the communication device 1 on the connected side is recognized as the upstream side (step S16). The transmission / reception control unit 20a notifies itself or another control unit that the wakeup frame has been received, starts the main clock (step S17), and ends the process.

  By performing such processing in the communication devices 2a, 2b, 2c, and 2d that are the slave nodes, the communication devices 2a, 2b, 2c, and 2d transition from the sleep state to the active state. Recognize the upstream connection.

  FIG. 5 is a sequence diagram illustrating a process in which a WKUP_m frame is transmitted from a master node to a slave node. When the communication device 1 starts transmission of the WKUP_m frame from the connection unit 12 recognized as the base point, first, the communication device 2a first connects to the connection unit 21a of the communication device 2a connected to the communication line 3a to which the connection unit 12 is connected. To receive the WKUP_m frame. The communication device 2a recognizes the connection unit 21a on the side receiving the WKUP_m frame as the master side (upstream side), and transmits the WKUP_m frame being received from the other connection unit 22a to the communication line 3b. At this time, the communication device 2a transitions to the active state upon receiving the WKUP_m frame.

  The WKUP_m frame is simultaneously transmitted from the communication device 2a to the communication device 2b via the communication line 3b, from the communication device 2b to the communication device 2c via the communication line 3c, and from the communication device 2c to the communication device 2d via the communication line 3d. Sent. Thereby, also in each of the communication devices 2b, 2c, and 2d, the connection units 21b, 21c, and 21d on the side receiving the WKUP_m frame are recognized as the master side (upstream side), and are distinguished from the other connection units 22b, 22c, and 22d. The

  When receiving the WKUP_m frame from the connection unit 21d, the communication device 2d transmits the WKUP_m frame from the connection unit 22d in the same manner as the communication devices 2a, 2b, and 2c of the other slave nodes. The connection unit 22d is connected to the connection unit 11 of the communication device 1 of the master node via the communication line 3e, and the connection in the entire system is annular. When the other connection unit 11 receives the WKUP_m frame transmitted from the base connection unit 12 by the other connection unit 11, the transmission / reception control unit 10 of the communication device 1 has a circular connection and the data is normally transmitted. Recognize that each slave node is reached. As described above, when the communication devices 2a, 2b, 2c, and 2d of each slave node receive the WKUP_m frame, the communication device 1 is transferred by sequentially transferring the WKUP_m frame from the other connection units 22a, 22b, 22c, and 22d. When the WKUP_m frame cannot be received from the connection unit 11, it can be recognized that an abnormality has occurred in communication at any of the slave nodes.

  If the communication device 2d receives the WKUP_m frame from both the connection unit 21d and the connection unit 22d, the transmission / reception control unit 20d recognizes the connection unit on the receiving side as the upstream side. Further, when the WKUP_m frame is received simultaneously by both the connecting unit 21d and the connecting unit 22d, it may wait until the WKUP_m frame is received again.

  Thereafter, each of the communication devices 1, 2a, 2b, 2c, and 2d distinguishes between the two connecting portions and basically communicates with the received LIN protocol. Specifically, when the ID of the header received from the master side (upstream side) connection unit 21a corresponds to itself, the communication device 2a transmits a response from the connection unit 22a following the header. The same applies to the communication devices 2b, 2c and 2d which are other slave nodes.

  Here, in the general LIN protocol, the ID of the header received from the master side identifies the slave node to which a response is to be made, based on an ID fixedly assigned to each communication device in advance. In contrast, in this embodiment, each ID is not fixed, and the header ID includes a numerical value set by the communication device 1 of the master node, and the communication devices 2a, 2b, 2c, and 2d of each slave node are Each time it transfers the header, it subtracts or adds the value. Each of the communication devices 2a, 2b, 2c, and 2d of each slave node determines that it corresponds to itself when the numerical value is a predetermined value (for example, zero or 0xF). The communication device 1 which is a master node initially transmits an arbitrary header from the connection unit 12 and receives the header transferred in a ring shape at the other connection unit 11 so that the numerical value of the header received through the transfer is received. It is possible to grasp the number of communication devices 2a, 2b, 2c, and 2d that pass through. Therefore, for example, when transmitting a header addressed to the communication device 2b where data reaches the second time, the communication device 1 transmits the header after setting the numerical value to be a predetermined value when the communication device 2b is reached. Thereby, a fixed ID may not be given in advance, and the configuration can be shared by the communication devices 2a, 2b, 2c, and 2d used for the slave nodes.

Moreover, it is good also as a structure which returns a response from several communication apparatuses at once instead of making it a response from one communication apparatus with respect to one header. Since the communication devices 2a, 2b, 2c, and 2d of each slave node are connected in a ring shape, the communication devices 2a, 2b, 2c, and 2d are pre-set bytes among a plurality of bytes of data following the header. It is also possible to send data from itself to the location. For example, the communication device 1 that is the master node includes the hop number in the header ID, and when the hop number is 0, the communication device 2a that receives the header first receives (DATA, SUM) in the first and second bytes. Transmission The communication device 2b that receives the header secondly transmits (DATA, SUM) at the third to fourth bytes. That is, the communication device that transmits the nth header based on the number of hops transmits (DATA, SUM) at (2 ⁿ −1) to 2 ⁿ bytes. Thereby, it is also possible to reduce the number of header transmissions.

  Next, processing when an abnormality occurs in communication on the communication line 3c between the communication devices 2b and 2c while data is transmitted / received between the communication devices 1, 2a, 2b, 2c, and 2d will be described. The communication devices 2a, 2b, 2c, and 2d of each slave node are connected so that one of two different connection portions is disconnected from the communication line when an abnormality occurs in communication with an adjacent communication device. Switch inside the department.

  FIG. 6 is a sequence diagram showing a process in which the connection is switched by each of the communication devices 1, 2a, 2b, 2c, 2d when a communication abnormality occurs in the in-vehicle communication system.

  The communication device 1 of the master node can detect that there is an abnormality when the response to the header transmitted from the connection unit 12 cannot be received by the other connection unit 11. The communication device 1 transmits a message frame that includes an ID corresponding to each of the communication devices 1 in order from the communication unit 2a from the connection unit 12 and returns a response. When the communication device 2a receives the message frame whose ID corresponding to itself, that is, the numerical information included therein is a predetermined value, at the upstream connection unit 21a, the communication device 2a transmits a response to the message frame from the upstream connection unit 21a. The communication device 1 sequentially adds and subtracts the numerical information included in the ID from the connection unit 12 and determines whether there is a response.

  As illustrated in FIG. 6, when a response to the message frame addressed to the communication device 2c cannot be received, the communication device 1 determines that there is an abnormality in communication between the communication device 2b and the communication device 2c.

  It is to be noted that each communication device 1, 2a, 2b, 2c, 2d is determined to be abnormal when communication cannot be performed at each connection unit 11, 12, 21a, 22a, 21b, 22b, 21c, 22c, 21d, 22d. Then, a message frame that informs the abnormality to the communication device 1 of the master node may be transmitted from the other connection unit capable of communication.

  When the communication device 1 determines that there is an abnormality in communication between the communication device 2b and the communication device 2c, the communication device 1b first switches from the transmission / reception control unit 20b to the bus switching unit of each of the connection units 21b and 22b. A message frame for instructing to output the instruction is transmitted from the connection unit 11. Thereby, the transmission / reception control unit 20b of the communication device 2b that has received the message frame of the switching instruction from the connection unit 21b is connected to the transmission terminal Tx of the second transmission / reception unit at the bus switching unit of the connection unit 22b different from the connection unit 21b. An instruction signal is output so as to short-circuit the receiving terminal Rx. Thereby, the inside of the connection unit 22b in the communication device 2b is in a loopback state, and the signal output from the transmission terminal Tx of the second transmission / reception unit is folded. At this time, since the communication device 2c still recognizes the connection unit 21c as the upstream side, the communication device 2c does not receive the message from the communication device 1 from 22c.

  Thereafter, the communication device 1 transmits the WKUP_m frame again in response to the separation between the communication device 2b and the communication device 2c due to the occurrence of an abnormality, and each communication device 2a, 2b, 2c, 2d Recognize the upstream connection. At this time, the communication device 1 transmits the WKUP_m frame from both of the different connection units 11 and 12. The communication devices 2a, 2b, 2c, and 2d re-recognize the connection unit that has received the WKUP_m frame as an upstream connection unit, as in the above-described initial process. Specifically, the communication device 2b re-recognizes the connection unit 21b as the upstream side, and the communication device 2c re-recognizes the connection unit 22c as the upstream side.

  Since the communication device 2c recognizes the connection unit 22c as the upstream side, the communication device 1 instructs the communication device 2c to output a switching instruction from the transmission / reception control unit 20c to the bus switching unit of the connection units 21c and 22c. The message frame to be transmitted is transmitted from the connection unit 12. The transmission / reception control unit 20c of the communication device 2c that has received the switching instruction message frame from the connection unit 22c recognized as the upstream side uses the bus switching unit of the connection unit 21c different from the connection unit 22c for transmission of the first transmission / reception unit. An instruction signal is output so as to short-circuit the terminal Tx and the receiving terminal Rx. Thereby, the inside of the connection unit 21c in the communication device 2c is in a loopback state, and the signal output from the transmission terminal Tx of the first transmission / reception unit is folded.

  As a result, not only the influence of the communication abnormality in the communication line 3c can be excluded from the entire system, but also the physically arranged state is maintained (the communication line 3c is apparently connected to the communication devices 2b and 2c). Can be reconfigured into a network of two linear topology configurations.

  FIG. 7 is an explanatory diagram conceptually showing a logical connection relationship that changes depending on the processing of the communication devices 1, 2a, 2b, 2c, and 2d in the present embodiment. As shown in FIG. 7, the connection form, which is a single ring type configuration, is logically two daisy chain types when the connection unit 22 b and the connection unit 21 c of the communication devices 2 b and 2 c are in a loopback state. Reconfigured to a linear topology.

  The data is logically reconfigured into two daisy-chain linear topologies, and the data received by the communication devices 2b and 2c are returned by the loopback state of the connection 22b and connection 21c that are disconnected. Since the communication device 1 of the master node can continue the communication independently through the two connection parts 11 and 12, even if an abnormality occurs in the communication on the communication line 3c, the transmission capacity of the entire system is prevented from being lowered. Is possible.

  The example of the above-described abnormality is an example in the case where an abnormality occurs in communication on the communication line 3c, such as the communication line 3c being disconnected. As another example of the abnormality, the case where an operation abnormality of the transmission / reception control unit 20c of the communication device 2c or the first transmission / reception unit and the second transmission / reception unit occurs is taken as an example. , 2c, 2d will be described.

  FIG. 8 is a sequence diagram illustrating a process in which connection is switched by each communication device 1, 2a, 2b, 2c, 2d when an operation abnormality of one communication device 2c occurs in the in-vehicle communication system. In the example of FIG. 8, an operation abnormality of the transmission / reception control unit 20c of the communication device 2c occurs, and the communication device 2c continuously transmits abnormal frames to the communication line 3c and the communication line 3d. The transfer of data transmitted from the communication device 2b and the transfer to the communication device 2d are continued. At this time, the communication device 1 as the master node cannot detect an abnormality depending on whether or not the data transmitted from the connection unit 12 can be received from the connection unit 11.

  The communication device 2b in the present embodiment monitors and records an error at two different connection portions 21b and 22b. The transmission / reception control unit 20b, the first transmission / reception unit of the connection units 21b and 22b, the second transmission / reception unit, or the monitoring unit may be monitored and recorded. Other slave node communication devices 2a, 2c, and 2d have the same function.

  For example, each time the monitoring unit 23b continues to receive an abnormal frame (for example, CRC is abnormal), the monitoring unit 23b counts the number of error detections, and when the number of error detections exceeds a preset threshold, the master node communication device 1 is notified to the transmission / reception control unit 20b. The transmission / reception control unit 20b that has received the notification includes a count result of the number of times of error detection from one of the connection unit 21b and the connection unit 22b, in this case the connection unit 21b that has not received an abnormal frame, and notifies the abnormality. Is transmitted to the communication device 1. In the case of the LIN protocol, an abnormality notification may be realized by transmitting it as a response to an inquiry from the master node. Similarly, the number of error detections is similarly counted in the monitoring unit 23d of the communication device 2d, and a message notifying the abnormality is transmitted from the connection unit 22d to the communication device 1.

  As a result, the communication device 1 that is the master node determines that there is an abnormality in communication between the communication device 2b and the communication device 2d. When the communication device 1 determines that there is an abnormality in communication between the communication device 2b and the communication device 2d, the communication device 1b first switches from the transmission / reception control unit 20b to the bus switching unit of each of the connection units 21b and 22b. A message frame for instructing to output the instruction is transmitted from the connection unit 11. Thereby, the transmission / reception control unit 20b of the communication device 2b that has received the message frame of the switching instruction from the connection unit 21b is connected to the transmission terminal Tx of the second transmission / reception unit at the bus switching unit of the connection unit 22b different from the connection unit 21b. An instruction signal is output so as to short-circuit the receiving terminal Rx. Thereby, the inside of the connection unit 22b in the communication device 2b is in a loopback state, and the signal output from the transmission terminal Tx of the second transmission / reception unit is folded. At this time, since the communication device 2d still recognizes the connection unit 21d as the upstream side, it does not receive the message from the communication device 1 from 22d.

  Thereafter, the communication device 1 transmits the WKUP_m frame again in response to the separation between the communication device 2b and the communication device 2d due to the occurrence of an abnormality, and the upstream side of each communication device 2a, 2b, 2d Re-recognize the connection. At this time, the communication device 1 transmits the WKUP_m frame from both of the different connection units 11 and 12. The communication devices 2a, 2b, and 2d re-recognize the connection unit that has received the WKUP_m frame as the upstream connection unit, as in the above-described initial process. Specifically, the communication device 2b re-recognizes the connection unit 21b as the upstream side, and the communication device 2d re-recognizes the connection unit 22d as the upstream side.

  Since the communication device 2d recognizes the connection unit 22d as the upstream side, the communication device 1 instructs the communication device 2d to output a switching instruction from the transmission / reception control unit 20d to the bus switching units of the connection units 21d and 22d. The message frame to be transmitted is transmitted from the connection unit 12. The transmission / reception control unit 20d of the communication device 2d that has received the switching instruction message frame from the connection unit 22d that is recognized as the upstream side uses the transmission terminal Tx of the first transmission / reception unit at the bus switching unit of the connection unit 21d different from the connection unit 22d. An instruction signal is output so as to short-circuit the receiving terminal Rx. Thereby, the inside of the connection unit 21d in the communication device 2d is in a loopback state, and the signal output from the transmission terminal Tx of the first transmission / reception unit 211d is folded.

  Thereby, not only the influence of the operation abnormality of the communication device 2c can be excluded from the entire system, but also the physically arranged state is maintained (the communication device 2c apparently communicates with the communication devices 2b and 2d). It is possible to reconfigure to a network of two linear topology configurations (while still connected via lines 3c, 3d).

  Next, a description will be given of the process when the communication device 2c in which an abnormal operation has occurred returns to a normal operation due to a reset or the like. FIG. 9 is a sequence diagram illustrating a process in which connections are switched by the communication devices 1, 2a, 2b, 2c, and 2d when the communication device 2c in which an operation abnormality has occurred in the in-vehicle communication system is restored.

  When the communication device 2c returns its operation due to a reset or the like, the communication device 2c transmits a WKUP_s frame from both the connection units 21c and 22c. In the communication device 2b, when the monitoring unit 23b detects the WKUP_s frame, it notifies the transmission / reception control unit 20b. The transmission / reception control unit 20b instructs the bus switching unit of the disconnected connection unit 22b to connect the transmission / reception terminals Tx and Rx of the first transmission / reception unit to the transmission / reception terminals Tx and Rx of the second transceiver, respectively. Output. Thereby, the connection part 22b is connected to the communication line 3c. Similarly, in the communication device 2d, the connection unit 22d is connected to the communication line 3d by the function of the monitoring unit 23d.

  The WKUP_s frames transmitted from the connection units 21c and 22c by the communication device 2c are received by the connection unit 12 of the communication device 1 and the connection unit 11 of the communication device 1 via the communication devices 2b and 2a, respectively. The communication device 1 that has received the WKUP_s frame at both the connection unit 11 and the connection unit 12 waits for a predetermined standby time, determines whether both the connection unit 11 and the connection unit 12 can receive data, and Determine if there is no break in the ring connection (Ring Break).

  When the transmission / reception control unit 10 of the communication apparatus 1 determines that the connection is not interrupted, the transmission / reception control unit 10 transmits a WKUP_m frame from the connection unit 12 that is initially set as a base point. Thereafter, as described with reference to FIG. 5, each communication device 2a, 2b, 2c, 2d recognizes the connection units 21a, 21b, 21c, 21d that have received the WKUP_m frame as the master side (upstream side), and is in an active state. As a result, communication using a normal ring topology is realized.

(Modification)
In the above example, the communication on each of the communication lines 3a, 3b, 3c, 3d, and 3e is all based on the LIN protocol. However, communication on some communication lines may be another communication protocol. FIG. 10 is a configuration diagram when communication between the communication devices 1, 2a, 2b, 2c, and 2d of the in-vehicle communication system is set to a different communication protocol.

  Also in the example illustrated in FIG. 10, the communication devices 1, 2 a, 2 b, 2 c, and 2 d are each configured to have two connection portions. However, the communication line 3c is replaced with the power supply line 6, and the communication line 3d and the communication line 3e are replaced with UTP (Unshielded Twist Pair) harnesses 71 and 72.

  Communication between the communication device 1 and the communication device 2a via the communication line 3a and the communication line 3b and communication between the communication device 2a and the communication device 2c are performed by the LIN protocol. Communication between the communication device 2b and the communication device 2c via the power line 6 is performed using a protocol corresponding to PLC (Power Line Communication). Communication between the communication device 2c and the communication device 2d via the communication line 71 and the communication line 72, and communication between the communication device 2d and the communication device 2a are performed by the CAN protocol. All communication is basically performed on a one-to-one basis.

  The communication device 1 is connected to the communication line 72 and the communication line 3a which are different by the two connection units 16 and 12 respectively. The connection unit 16 implements communication using the CAN protocol. Note that the internal configuration of the connection unit 16 includes the first transmission / reception unit having transmission / reception terminals Tx and Rx for inputting and outputting signals based on the CAN protocol, the bus switching unit, and the transmission / reception terminals Tx and Rx, similarly to the connection unit 12. It is configured to include a CAN transceiver (not shown). Similarly, the bus switching unit has a function of switching the connection between the transmission / reception terminals Tx, Rx of the first transmission / reception unit and the transmission / reception terminals Tx, Rx of the CAN transceiver and the connection of the transmission / reception terminals Tx, Rx of the first transmission / reception unit. Have.

  The communication device 2b is bus-connected to the communication line 3b and the power supply line 6 by the connection unit 21b and the connection unit 24b. The connection unit 24b realizes communication using a protocol corresponding to the PLC. Similarly, the internal configuration includes a second transmission / reception unit, a bus switching unit, and a PLC transceiver (not shown). By the function of the bus switching unit, switching can be performed so as to be in a loopback state in the connection unit 24b.

  The communication device 2c is connected to the power line 6 and the communication line 71 by buses at the connection portions 24c and 25c. Similar to the connection unit 24b, the connection unit 24c realizes communication using a protocol corresponding to the PLC. Similarly to the connection unit 16 of the communication device 1, the connection unit 25c includes a second transmission / reception unit, a bus switching unit, and a CAN transceiver, and is in a loopback state in the connection unit 25c by the function of the bus switching unit. You can switch to The communication device 2d is bus-connected to the communication line 71 and the communication line 72 by the connection unit 25d and the connection unit 26d, respectively. The connection unit 25d of the communication device 2d is the same as the connection unit 16, and the connection unit 26d is the same as the connection unit 25c.

  Further, as shown in FIG. 10, not only the communication device 1 and the communication device 2a but also the communication device 4 and the sensor 5 which are other slave nodes are connected to the communication line 3a by a bus. As described above, other communication devices may be connected to the communication lines 3a and 3b, the power supply line 6, and the communication lines 71 and 72 in addition to the two communication devices. Even in the case of such a configuration, signal waveform deterioration in each communication line 3a, 3a, 71, 72 or power supply line 6 than the configuration in which all communication devices, sensors, etc. are connected to a single communication line by bus. Is reduced.

  In this way, by adopting a configuration in which communication devices are basically connected one-to-one, communication based on different protocols can be mixed between the communication devices as necessary. It is also possible to reduce the cost of the entire system as necessary, such as using a method with high noise resistance only in a specific section and hardware resources corresponding to the method. In addition, by adopting a configuration in which communication by the PLC method via the power line 6 can be performed only between the communication devices 2b and 2c, it is possible to reduce the wiring of the harness arranged in the vehicle by using the power line 6 and communication together. It can also be realized.

  The disclosed embodiments should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Communication device (master node)
DESCRIPTION OF SYMBOLS 11, 12 Connection part 111 1st transmission / reception part 112 Bus switching part 113 1st transceiver 121 2nd transmission / reception part 122 Bus switching part 123 2nd transceiver 2a, 2b, 2c, 2d Communication apparatus (slave node)
21a, 22a, 21b, 22b, 21c, 22c, 21d, 22d connection unit 211a first transmission / reception unit 212a bus switching unit 213a first transceiver 221a second transmission / reception unit 222a bus switching unit 223a second transceiver 23a, 23b monitoring unit 3a, 3b, 3c, 3d, 3e Communication line 6 Power supply line 71, 72 Communication line

Claims (13)

In a communication system in which a plurality of communication devices communicate with each other via a communication line,
Some or all of the plurality of communication devices are
It has two connections that connect to two different communication lines separately,
A communication system, characterized in that each of the other two communication devices is connected to the two connection units via different communication lines. In a communication system including one master communication device and a plurality of slave communication devices, each communication device being connected and communicating via a communication line,
Some or all of each communication device
Two different communication lines are connected to the two different communication lines, respectively, and are connected to the other two communication devices via different communication lines, respectively.
The slave communication device is
When the information transmitted from the master communication device is received by one of the two connection units, when the received information corresponds to itself, a response corresponding to the information is transmitted from the one and received. When the received information does not correspond to itself, the received information is transferred from the other. Each communication device
Determining means for determining normality / abnormality of communication with other connected communication devices;
3. The communication system according to claim 1, further comprising: a unit that disconnects a connection at a connection unit via communication with a communication device that is determined to be abnormal when the determination unit determines that the abnormality is present. The master communication device transmits a specific signal,
Each communication device
Of the two connections, whether the connection that received the specific signal is recognized as upstream and the other connection as downstream, and the data received from the upstream connection is transferred from the downstream connection Or a response to the data received by the upstream connection unit is transmitted from the downstream connection unit,
When disconnecting the connection at the upstream connection portion, the other connection portion recognized as the downstream side is re-recognized as the upstream connection portion,
The communication system according to claim 3, wherein when data is received from a connection unit re-recognized as the upstream side, a response is transmitted from the connection unit on the upstream side. The connection part of each communication device
A transceiver having a transmission / reception terminal, executing transmission of a signal input to the transmission terminal to the communication line, and output from the reception terminal of a signal received from the communication line;
A transceiver terminal having a transceiver terminal connected via a switch, and a transceiver unit for inputting / outputting a signal to be transmitted / received to / from the transceiver;
5. The communication according to claim 1, wherein the switch is configured to be able to switch between a connection of a transmission / reception terminal of the transmission / reception unit to a transceiver and a short circuit between the transmission / reception terminals. system. Each communication device
6. The apparatus according to claim 5, further comprising means for outputting an instruction to switch to a short circuit between the transmission / reception terminals of the transmission / reception unit to the connection unit via the communication determined to be abnormal when the determination unit determines that there is an abnormality. The communication system described. The connection unit of the communication device includes a monitoring unit that monitors the output of the reception terminal of the transceiver,
The monitoring unit
The communication system according to claim 5 or 6, further comprising means for detecting a signal corresponding to an external connection return instruction set in advance. The master communication device is
A determination means for determining normality / abnormality of communication in another communication device;
The switching means for switching to a short circuit between the transmission / reception units of the connection unit is transmitted to a communication apparatus having a connection unit through which the determination unit determines that the communication is abnormal. Communication system. Any two of the communication devices that can be connected are:
Communication according to a communication protocol different from communication between other communication devices or communication via a communication medium different from communication between other communication devices is performed. The communication system described. The communication system according to any one of claims 1 to 9, wherein each communication device communicates based on a LIN (Local Interconnect Network). It has two connections that are bus-connected to two different communication lines,
The two connections are respectively
A transceiver having a transmission / reception terminal, executing transmission of a signal input to the transmission terminal to the communication line, and output from the reception terminal of a signal received from the communication line;
A transceiver terminal having a transceiver terminal connected via a switch, and a transceiver unit for inputting / outputting a signal to be transmitted / received to / from the transceiver;
The switch is configured to be capable of switching between connection of a transmission / reception terminal of the transmission / reception unit to a transceiver and a short circuit between the transmission / reception terminals. Means for determining normality / abnormality of communication in the two connection portions;
The means for switching to a short circuit between the transmission / reception terminals of the transmission / reception unit is output to the connection unit determined to be abnormal when the unit determines that there is an abnormality. Communication device. In a communication system including one master communication device and a slave communication device, each communication device communicates with another communication device via a communication line.
A part or all of each communication device includes two connection portions that are respectively connected to two different communication lines by buses, and the other two communication devices are connected via different communication lines depending on the two connection portions. Connected to communicate,
The slave communication device is
When the information transmitted from the master communication device is received by one of the two connection units, when the received information corresponds to itself, a response corresponding to the information is transmitted from the other,
When the received information does not correspond to itself, transfer the received information from the other,
Each communication device
Determine the normality / abnormality of communication with other connected communication devices,
If determined to be abnormal, disconnect the connection at the connection with the communication line via communication with other communication devices determined to be abnormal,
When information is received by a connection unit different from the connection unit, the information is returned by the disconnected connection unit.

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