JP2015088919A - Communication system and communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system having a simple configuration and capable of suppressing increase in noise, and a communication device essentially constituting the communication system.SOLUTION: A communication system comprises three or more communication devices daisy chain connected using a plurality of twist pair lines 3, and each of the three or more communication devices 1 communicates by receiving or outputting differential signals. A communication device (ECU) 1 connected with two twist pair lines 3 comprises: a first terminal 16a to which one part of voltage representing a differential signal should be applied, and a second terminal 16b to which the other part of voltage representing the differential signal should be applied; a first connection part electrically connecting one signal line of one twist pair line 3, one signal line of the other twist pair line 3, and the first terminal; and a second connection part electrically connecting the other signal line of the one twist pair line 3, the other signal line of the other twist pair line 3, and the second terminal.

Description

  The present invention relates to a communication system that performs communication using differential signals and a communication device used in the communication system.

  Conventionally, a lot of electronic devices (communication devices) are mounted on a vehicle, and each electronic device is connected via a communication line and cooperates while exchanging information with each other. In addition, control and the like related to comfort in the passenger compartment are realized. When an electronic device mounted on a vehicle performs communication, CAN (Controller Area Network) is widely adopted as a communication protocol (see Non-Patent Document 1).

  In general, in a communication system employing a CAN communication protocol, a twisted pair wire in which a pair of signal lines is twisted is used as a communication line, and each electronic device performs communication using a differential signal. In general, a communication system adopting a CAN communication protocol adopts a bus type network topology. In a bus-type network topology, each electronic device is connected to a branch line that branches from a main line used for communication in common with other electronic devices. In Non-Patent Document 2, the length of the branch line is defined as a maximum of 30 cm when the communication speed is 1 Mbps.

ISO 11898-1: 2003 Road vehicles--Controller area network (CAN)-Part1: Data link layer and physical signaling ISO 11898-2: 2003 Road vehicles--Controller area network (CAN)-Part2: High-speed medium access unit

  In the above-described bus-type network topology, branching from a trunk line to a branch line is realized by using a branch connector or by crimping or pressing a communication line to be a branch line to a communication line that is a trunk line. As the number of communication devices that perform communication increases, the number of branch points from the trunk line to the branch line increases, and the connection cost increases due to an increase in the number of parts. In addition, since the number of branch points increases, the labor for connection increases. In addition, when branching, the communication line to be the branch line is connected to the communication line that becomes the trunk line by untwisting the pair of signal lines, so that when the length is as short as 30 cm as described above, There is a risk that noise including ringing and electromagnetic noise may increase due to a decrease in length.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a communication system capable of suppressing an increase in noise with a simple configuration and a communication apparatus constituting the communication system.

  A communication system according to the present invention includes three or more communication devices connected in a daisy chain using a plurality of twisted pair wires in which a pair of signal wires are twisted, and each of the three or more communication devices is connected. A communication system for performing communication by inputting and outputting a differential signal represented by a difference between two voltages applied to each of the twisted pair lines, wherein the communication is connected to the two twisted pair lines. The apparatus includes: a first terminal to which one voltage representing the differential signal is to be applied; a second terminal to which the other voltage representing the differential signal is to be applied; and one signal in one twisted pair line. A first connection portion electrically connecting the first signal line in the other twisted pair line and the first terminal, the other signal line of the one twisted pair line, and the other twisted pair Characterized in that it comprises a second connecting portion which is connected the other signal lines, and the second terminal electrically in.

  In the present invention, a communication device connected to two twisted pair wires includes a first terminal to which one voltage representing a differential signal is to be applied. The communication device connected to the two twisted pair wires includes a second terminal to which the other voltage representing the differential signal is to be applied. The communication device connected to the two twisted pair lines electrically connects one signal line in one of the two twisted pair lines, one signal line in the other, and the first terminal at the first connection portion. It is. The communication device connected to the two twisted pair lines electrically connects one signal line in one of the twisted pair lines, the other signal line in the other, and the second terminal at a second connection portion. It is. The differential signal transmitted by one communication device is transmitted to the communication device connected to the communication device via the first connection unit and the second connection unit included in each of the other communication devices connected to the two twisted pair wires. And a signal is transmitted to a communication part via the said 1st connection part and 2nd connection part. Therefore, the first connection portion and the second connection portion serve as a branch, and it is not necessary to separately provide a branch in the twisted pair wire, and it is not necessary to untwist the twisted pair wire for the branch. Each device can communicate. In addition, the twisted pair wire is only connected to the communication device, and it is not necessary to untwist the twisted pair wire for branching. Therefore, an increase in noise including ringing and electromagnetic noise can be suppressed.

  In the communication system according to the present invention, the first connection part and the second connection part are wiring patterns formed on a circuit board.

  In the present invention, the first connection portion and the second connection portion are wiring patterns formed on the circuit board. Therefore, since the first connection part and the second connection part that play a role of branching can be formed in advance with a wiring pattern, for example, the wiring pattern is applied to a circuit board used in a communication device connected to two twisted pair wires. By forming, a simpler configuration can be obtained.

  In the communication system according to the present invention, the first connection portion and the second connection portion are wiring patterns formed on different surfaces of the circuit board.

  In the present invention, the first connection portion and the second connection portion formed in the wiring pattern on the circuit board are formed on different surfaces on the circuit board. Therefore, it is possible to prevent the wiring pattern corresponding to the second connection portion or the first connection portion from being detoured due to the wiring pattern corresponding to the first connection portion or the second connection portion.

  In the communication system according to the present invention, at least one of the communication devices includes a phase shift unit that shifts a phase of a differential signal to be input and output.

  In the present invention, at least one communication device includes a phase shift unit that shifts the phase of a differential signal to be input and output. Therefore, when one communication device is connected to, for example, a communication device that includes a phase shift unit and a communication device that does not include a phase shift unit, a reflected wave when the one communication device transmits a signal. Can be shifted in phase. Therefore, ringing can be suppressed.

  In the communication system according to the present invention, there are four or more communication devices, and at least one of the two communication devices at both ends of the three communication devices connected in series includes the phase shift unit. In addition, the phase shift amounts of the differential signals inputted to and outputted from the two communication devices at both ends are different from each other.

  In the present invention, four or more communication devices are provided. Of the three communication devices connected in series, at least one of the two communication devices at both ends includes a phase shift unit, and each differential signal is input to and output from the two communication devices at both ends. The phase shift amount differs. Therefore, when one communication device is connected to, for example, a communication device that includes a phase shift unit and a communication device that does not include a phase shift unit, a reflected wave when the one communication device transmits a signal. Can be shifted in phase. Further, even when one communication device is connected to, for example, two communication devices each having a phase shift unit, the phase shift amount of each phase shift unit is made different from each other, thereby The phase of the reflected wave when the device transmits a signal can be shifted. Therefore, ringing can be suppressed.

  In the communication system according to the present invention, the phase shift amounts of the differential signals respectively inputted to and outputted from at least one set of the two consecutive communication devices out of the four consecutively connected communication devices match. It is characterized by the above.

  In the present invention, the phase shift amounts of the differential signals input / output to / from at least one set of two consecutive communication devices out of the four communication devices connected in series match. For example, when a communication system is constructed by alternately connecting two communication device groups that include a phase shift unit and two communication device groups that do not include a phase shift unit, among four consecutively connected communication devices The phase shift amounts of the differential signals input / output to / from the two communication devices match. Further, in the communication system, the phase shift amount of the differential signal input / output to / from the communication devices at both ends of the three consecutive communication devices is different, and ringing in the differential signal transmitted by the center of the three communication devices Can be suppressed. Therefore, it is possible to construct a communication system in which ringing is suppressed with at least one type of phase shift unit.

  The communication system according to the present invention is characterized in that the terminal communication device includes a terminal circuit interposed between a pair of signal lines constituting a connected twisted pair line.

  In the present invention, the terminal communication device includes a terminal circuit interposed between a pair of signal lines constituting a connected twisted pair line. Therefore, the terminating communication device can match the value of the input impedance by the terminating circuit with the value of the characteristic impedance of the twisted pair wire connected thereto, and thus can suppress ringing.

  A communication system according to the present invention includes three or more communication devices connected in a daisy chain using a plurality of twisted pair wires in which a pair of signal wires are twisted, and each of the three or more communication devices is connected. A communication system for performing communication by inputting and outputting a differential signal represented by a difference between two voltages applied to each line of the twisted pair line, wherein the communication apparatus is connected to the two twisted pair lines. Each of the communication devices includes a first terminal to which one voltage representing the differential signal is applied and a second terminal to which the other voltage is applied, and is connected to the two twisted pair wires. A connector interposed in one twisted pair wire, the connector including one signal line in one of the twisted pair wires, one signal line in the other twisted pair wires, and the first end Are electrically connected to the first connection part, the other signal line in the one twisted pair line, the other signal line in the other twisted pair line, and the second terminal. And 2 connecting portions.

  In the present invention, a communication device connected to two twisted pair wires includes a first terminal to which one voltage representing a differential signal is to be applied and a second terminal to which the other voltage is to be applied. . In addition, the communication system includes a communication device connected to two twisted pair wires and a connector interposed between the two twisted pair wires. In the connector, one signal line in one of the two twisted pair wires, one signal line in the other, and the first terminal are electrically connected by the first connection portion. In the connector, the other signal line in one of the twisted pair wires, the other signal line in the other, and the second terminal are electrically connected by a second connection portion. The differential signal transmitted by one communication device is transmitted to the communication device connected to the communication device via the first connection unit and the second connection unit included in each of the other communication devices connected to the two twisted pair wires. And a signal is transmitted to a communication part via a 1st connection part and a 2nd connection part. Accordingly, the first connection unit and the second connection unit play a role of branching, and it is not necessary to provide a separate branch, so that each communication device can communicate with a simple configuration. In addition, the twisted pair wire is simply connected to the communication device via the connector, and it is not necessary to provide a branch in the twisted pair wire, and it is not necessary to untwist the twisted pair wire for the branch, so that noise including ringing and electromagnetic noise is included. Can be suppressed.

  The communication system according to the present invention is characterized in that at least one of the connectors includes a phase shift unit that shifts a phase of a differential signal input and output by the connected communication device.

  In the present invention, at least one connector includes a phase shift unit that shifts a phase of a differential signal input and output by a connected communication device. Thus, for example, when one communication device is connected to a communication device connected to a connector having a phase shift unit and a communication device connected to a connector not having a phase shift unit, the one communication device The phase of the reflected wave when the communication device transmits a signal can be shifted.

  The communication device according to the present invention is a communication device to be connected to two twisted pair wires in which a pair of signal lines are twisted together, and a first terminal to which one voltage representing a differential signal is to be applied, and the difference The second terminal to which the other voltage representing the dynamic signal is to be applied is electrically connected to one signal line in one of the twisted pair lines, one signal line in the other twisted pair line, and the first terminal. And a second connection part to electrically connect the other signal line in the one twisted pair line, another signal line in the other twisted pair line, and the second terminal. Features.

  In the present invention, one voltage representing a differential signal is applied to the first terminal. The other terminal representing the differential signal is applied to the second terminal. The first connection portion electrically connects one signal line in one of the two twisted pair lines, one signal line in the other, and the first terminal. The second connection unit electrically connects the other signal line in one of the twisted pair lines, the other signal line in the other, and the second terminal. Therefore, for example, when communicating with a plurality of communication devices, the first connection unit and the second connection unit play a role of branching in the communication line, so that it is possible to communicate with each communication device with a simple configuration. Further, for example, when communicating with a plurality of communication devices, the twisted pair wire is only connected to one communication device, and there is no need to provide a branch for connecting to the plurality of communication devices, and the twisted wire is twisted for the branch. Therefore, it is possible to suppress an increase in noise including ringing and electromagnetic noise.

  According to the present invention, it is possible to construct a communication system that has a simple configuration and can suppress an increase in noise.

1 is a schematic diagram illustrating an overall configuration of a communication system according to Embodiment 1. FIG. It is a block diagram which shows the structure of ECU. It is explanatory drawing which shows the structure of a connection part. It is a block diagram which shows the structure of terminal ECU. 6 is a block diagram showing a configuration of an ECU in a second embodiment. FIG. It is explanatory drawing which shows the structure of a connection part. FIG. 9 is a schematic diagram showing an overall configuration of a communication system in a third embodiment. It is a block diagram which shows the structure of ECU. FIG. 10 is a schematic diagram illustrating an overall configuration of a communication system according to a fourth embodiment. FIG. 10 is a block diagram showing a configuration of a male connector in a fifth embodiment.

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

(Embodiment 1)
FIG. 1 is a schematic diagram showing an overall configuration of the communication system according to the first embodiment. The communication system according to the first embodiment includes a plurality of ECUs (Electronic Control Units) 1 mounted on the vehicle, two terminal ECUs 2 mounted on the vehicle, and a plurality of twisted pair wires 3. In the communication system, the ECU 1 and the terminal ECU 2 are connected in a daisy chain manner by a plurality of twisted pair wires 3, both ends are the terminal ECU 2, and the plurality of ECUs 1 are arranged in the middle. In FIG. 1, the plurality of ECUs 1 are distinguished from each other with reference numerals 1a to 1e, and the two terminal ECUs 2 are distinguished from each other with reference numerals 2a and 2b. Similarly, the plurality of twisted pair wires 3 are distinguished from each other by being denoted by reference numerals 3a to 3f. That is, the communication system in FIG. 1 has a terminal ECU 2a as one end, and ECUs 1a to 1e and a terminal ECU 2b are connected in series via twisted pair wires 3a to 3f in this order. Moreover, ECU1 and termination | terminus ECU2 are corresponded to the communication apparatus in this invention.

  The twisted pair wire 3 is a communication wire in which a pair of signal wires are twisted together, and it does not matter whether or not the insulator is covered. The ECU 1 is connected to the two twisted pair wires 3 via a connector, which will be described later. In the communication system configured as described above, the ECU 1 and the terminating ECU 2 each output a differential signal to the connected twisted pair wire 3 or input a differential signal from the twisted pair wire, thereby allowing the other ECU 1 and the terminating ECU 2 to Communicate with.

  FIG. 2 is a block diagram showing the configuration of the ECU 1a. The ECU 1 a is connected to the two twisted pair wires 3 a and 3 b via the connector 4. The connector 4 has a male connector 42 connected to the two twisted pair wires 3a and 3b, and a female connector 41 connected to the ECU 1. The female connector 41 has four pins as terminals and is connected to a connection portion 17 provided in the ECU 1 described later. In the first embodiment, the connector 4 has been described in which the male connector 42 is connected to the two twisted pair wires 3a and 3b and the female connector 41 is connected to the ECU 1. However, the connection relationship is reversed. There may be. That is, the female connector 41 may be connected to the two twisted pair wires 3a and 3b, and the male connector 42 may be connected to the ECU 1. In the first embodiment, the configuration of the ECU 1a will be described. However, the other ECUs 1b to 1e have the same configuration as the ECU 1a, and thus the description thereof is omitted.

  The ECU 1 includes a circuit board, and a control unit 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, an input unit 14, an output unit 15, a driver 16, a connection unit 17, and the like are mounted on the circuit board. Has been. The control unit 11 is configured using an arithmetic processing device such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and performs various controls by reading and executing a control program stored in the ROM 12. Processing can be performed.

The ROM 12 is configured by a nonvolatile memory element such as an EEPROM (Electrically Erasable Programmable ROM) or flash memory, for example, and a control program executed by the control unit 11 and information necessary for processing performed by the control unit 11 Etc. are stored in advance. The RAM 13 is configured by a memory element such as SRAM (Static RAM) or DRAM (Dynamic RAM), for example, and is transmitted and received between the information generated by the processing of the control unit 11 and the other ECUs 1b to 1e. Various information such as information to be stored is stored.

  The input unit 14 receives a signal from an input device such as a sensor such as a vehicle speed sensor or a temperature sensor of the vehicle, or various switches for operation disposed inside and outside the vehicle, and performs sampling of the input signal or A / Information obtained by performing processing such as D conversion is given to the control unit 11. The output unit 15 is connected to a load such as a motor or a lamp, and outputs a drive signal for driving these loads in response to an instruction from the control unit 11. Note that the ECU 1a does not necessarily include both the input unit 14 and the output unit 15, and may be configured to include only one of them.

  The driver 16 transmits and receives information according to the CAN protocol between the other ECUs 1b to 1e and the terminal ECU 2, and has a pair of terminals 16a and 16b. The pair of terminals 16a and 16b are electrically connected to the two twisted pair wires 3a and 3b via a connecting portion 17 and a connector 4 which will be described later. Specifically, one signal line 31a included in the twisted pair line 3a and one signal line 31b included in the twisted pair line 3b are electrically connected to the terminal 16a, and the other signal lines 32a included in the twisted pair line 3a Another signal line 32b included in the twisted pair line 3b is electrically connected to the terminal 16b.

  The driver 16 includes a transmission unit 16c and a reception unit 16d. The driver 16 converts the transmission information given from the control unit 11 into transmission data (frame) according to the CAN protocol and gives the data to the transmission unit 16c. The transmission unit 16c of the driver 16 has two twisted pair wires 3a connected via the connection unit 17 and the connector 4 in accordance with the value of each bit (0 (dominant) or 1 (recessive)) of given transmission data. And 3b are output differential signals. When transmitting a dominant signal, the transmitter 16c applies a different voltage value to each of the pair of terminals 16a and 16b so that the potential difference between the pair of signal lines constituting the twisted pair line is 2V. A dynamic signal is output. When transmitting a recessive signal, the transmitter 16c outputs a differential signal by applying the same voltage value to each of the pair of terminals 16a and 16b so that the potential difference becomes 0V. One of the pair of terminals 16a and 16b corresponds to a first terminal, and the other corresponds to a second terminal.

  The receiving unit 16d of the driver 16 detects a potential difference between the pair of terminals 16a and 16b to determine whether the signal transmitted on the twisted pair wires 3a and 3b is a signal corresponding to dominant or recessive. Then, data in which each bit is represented by dominant or recessive is received. The driver 16 gives the data received by the receiving unit 16d to the control unit 11. Further, the driver 16 receives the data transmitted by the transmission unit 16c at the reception unit 16d, and the transmission data does not match the reception data (the recessiveness of the transmission data has changed to dominant in the reception data). ), It is detected that data is being transmitted by the other ECUs 1b to 1e or the terminal ECU 2, and arbitration processing is performed. The arbitration process performed by the ECU 1a is the same as that performed by the conventional CAN protocol, and thus detailed description thereof is omitted.

  The connection portion 17 is a wiring pattern formed on the circuit board, and electrically connects the pair of terminals 16 a and 16 b included in the driver 16 and the four pins of the female connector 41. Below, the specific structure of the connection part 17 is demonstrated.

  FIG. 3 is an explanatory diagram illustrating the configuration of the connection unit 17. FIG. 3 schematically shows a rectangular parallelepiped female connector 41 and a flat circuit board 18 provided in the ECU 1. For example, the female connector 41 is fixed so that its longitudinal direction runs along one edge of the circuit board 18 and rises vertically from one surface of the circuit board 18. On the front and back surfaces of the circuit board 18, wiring patterns 18 a and 18 b connected to the terminals 16 a and 16 b (not shown) of the driver 16 are formed toward one end edge where the female connector 41 is provided. The wiring pattern 18a is bifurcated near the female connector 41 to form wiring patterns 17a and 17b. Similarly, the wiring pattern 18b is bifurcated near the female connector 41 to form wiring patterns 17c and 17d. Here, the wiring patterns 17 a to 17 d including the branch portions constitute the connection portion 17.

  The female connector 41 has four pins 41a, 41b, 41c, and 41d arranged in parallel in the longitudinal direction. One end sides of the pins 41 a to 41 d are embedded in the female connector 41. A signal line 31a is connected to one end of the pin 41a via a male connector 42, and a signal line 32a is connected to one end of the pin 41b via a male connector 42. Similarly, the signal line 31b is connected to one end of the pin 41c via the male connector 42, and the signal line 32b is connected to one end of the pin 41d via the male connector 42. The other sides of the pins 41a to 41d extend parallel to the surface of the circuit board 18 and are bent at substantially right angles toward the surface. The other ends of the pins 41a and 41c are wiring patterns on the surface of the circuit board 18. 17a and 17b. The other ends of the pins 41b and 41d pass through the circuit board 18 and reach the back surface, and are connected to the wiring patterns 17c and 17d.

  By configuring the connection portion 17 in this way, the pins 41a, 41c, and one terminal 16a of the driver 16 (not shown) are electrically connected by the wiring patterns 17a and 17b. That is, the wiring patterns 17a and 17b electrically connect one signal line 31a in the twisted pair line 3a, one signal line 31b in the twisted pair line 3b, and one terminal 16a through the pin 41a and the pin 41c. . Similarly, the pin 41b, the pin 41d, and the other terminal 16b of the driver 16 (not shown) are electrically connected by the wiring patterns 17c and 17d. That is, the wiring patterns 17c and 17d electrically connect the other signal line 32a in the twisted pair line 3a, the other signal line 32b in the twisted pair line 3b, and the other terminal 16b through the pin 41b and the pin 41d. . Each set of the wiring patterns 17a and 17b and 17c and 17d corresponds to a first connection part and a second connection part.

  FIG. 4 is a block diagram showing a configuration of the terminal ECU 2. The termination ECU 2 includes a control unit 21, a ROM 22, a RAM 23, an input unit 24, an output unit 25, a driver 26, a termination circuit 27, and the like. Here, since the control part 21, ROM22, and RAM23 operate | move similarly to the control part 11, ROM12, and RAM13 in FIG. 2, description is abbreviate | omitted. The input unit 24, the output unit 25, and the driver 26 are the same as the input unit 14, the output unit 15, and the driver 16 in FIG. The terminal ECU 2 is connected to one twisted pair wire 3.

  The termination circuit 27 is arranged between the twisted pair line 3 connected to the driver 26 and includes a series circuit including two resistors 27 a between a pair of signal lines included in the twisted pair line 3. Yes. The termination circuit 27 includes a capacitor 27b. One end of the capacitor 27b is connected between the two resistors 27a, and the other end is grounded. The termination circuit 27 configured in this way is a so-called split termination in the CAN protocol, and matches the input impedance to the driver 26 with the characteristic impedance of the connected twisted pair wire 3. Note that the termination circuit 27 may be a termination resistor and may be configured other than the split termination.

  In the communication system configured as described above, when one ECU 1 or the terminal ECU 2 transmits a differential signal, the other ECU 1 receives the differential signal from one of the connected twisted pair wires 3. At this time, for example, the differential signal is transmitted to the wiring patterns 17a and 17b (or 17c and 17d) via the pins 41a and 41b (or 41c and 41d), and then transmitted to the driver 16 via the wiring patterns 18a and 18b. Entered. Further, when the differential signal is transmitted to the wiring patterns 17a and 17b (or 17c and 17d), it is transmitted to the wiring patterns 17c and 17d (or 17a and 17b) by each branch portion, and the pins 41c and 41d (or 41a) are transmitted. And 41b) to the other twisted pair wire 3 connected thereto. For example, the differential signal output from the terminal ECU 2a is transmitted to the ECU 1a via the twisted pair wire 3a. The differential signal is transmitted to the wiring patterns 17a and 17b included in the ECU 1a, and is input to the driver 16 included in the ECU 1a via the wiring patterns 18a and 18b. The differential signal is transmitted through the wiring patterns 17c and 17d, and is transmitted to the ECU 1b via the twisted pair wire 3b. Similarly, the differential signals are sequentially transmitted from the ECU 1b to the ECU 1c, from the ECU 1c to the ECU 1d, from the ECU 1d to the ECU 1e, and from the ECU 1e to the terminal ECU 2b. Therefore, the connecting portion 17 in the ECU 1 serves as a branch, and it is not necessary to separately provide a branch in the twisted pair wire 3. Therefore, a communication system in which the ECU 1 and the terminal ECU 2 can communicate with each other can be constructed with a simple configuration. In addition, since the twisted pair wire 3 connected to the ECU 1 does not need to be untwisted for branching, an increase in noise including ringing and electromagnetic noise can be suppressed. Further, since the connection portion 17 is formed as the wiring patterns 17a to 17d on the circuit board 18, it is not necessary to provide a branch circuit or the like, and a simpler configuration can be achieved. Furthermore, since the wiring patterns 17a to 17d are formed on different surfaces of the circuit board 18, it is possible to prevent each wiring pattern from being detoured.

(Embodiment 2)
In the first embodiment, it has been described that the connection portion 17 of the ECU 1 electrically connects the driver 16 and each of the two twisted pair wires 3. In the second embodiment, an example in which the connector 4 has a function corresponding to the connecting portion 17 will be described. Since the other configurations and operations except the configurations and operations described below are the same as those in the first embodiment, detailed description on the same configurations and descriptions of the operations and effects are omitted for the sake of brevity.

  FIG. 5 is a block diagram showing a configuration of the ECU 1a in the second embodiment. The female connector 41 has a connection portion 43, and the pair of terminals 16 a and 16 b included in the driver 16 and the two twisted pair wires 3 a and 3 b are electrically connected by the connection portion 43. . Below, the specific structure of the connection part 43 is demonstrated.

  FIG. 6 is an explanatory diagram illustrating the configuration of the connection unit 43. The female connector 41 is provided with a connecting portion 43. Here, in FIG. 6, the outer shell of the female connector 41 is indicated by a two-dot chain line in order to clearly show the configuration of the connection portion 43.

  The connection unit 43 includes pins 43a and 43b. The pins 43a and 43b are spaced apart in the rising direction of the female connector 41 so as not to contact each other. The pins 43a and 43b have one end side extending in parallel on the surface of the circuit board 18 and bent at a substantially right angle toward the surface, and one end of the pins 43a and 43b is connected to the wiring pattern 18a and the surface of the circuit board 18. 18b. The other sides of the pins 43a and 43b are bifurcated in the outer shell of the female connector 41. The two branched ends of the pin 43a are connected to the signal lines 31a and 31b via the female connector 41, and the two branched ends of the pin 43b are connected to the signal lines 32a and 32b via the male connector 41. doing.

  The pin 43a configured in this manner electrically connects one signal line 31a in the twisted pair line 3a, one signal line 31b in the twisted pair line 3b, and one terminal 16a through the wiring pattern 18a. . Further, the pin 43b electrically connects the other signal line 32a in the twisted pair line 3a, the other signal line 32b in the twisted pair line 3b, and the other terminal 16b through the wiring pattern 18b. In the second embodiment, the pins 43a and 43b correspond to the first connection portion and the second connection portion in the present invention.

  In the communication system having the above configuration, the connecting portion 43 in the connector 4 serves as a branch, and it is not necessary to separately provide a branch in the twisted pair wire 3. Therefore, the communication system in which the ECU 1 and the terminal ECU 2 can communicate with each other with a simple configuration. Can be built. In addition, since the twisted pair wire 3 connected to the ECU 1 does not need to be untwisted for branching, an increase in noise including ringing and electromagnetic noise can be suppressed.

  In the second embodiment, the wiring patterns 18a and 18b may be formed on different surfaces of the circuit board 18.

(Embodiment 3)
In the third embodiment, in addition to the configuration of the communication system of the first and second embodiments described above, ringing can be suppressed by using a configuration that shifts the phase of the differential signal input and output by the ECU 1. An example of a communication system will be described. Since the other configurations and operations except for the configurations and operations described below are the same as those in the first and second embodiments, a detailed description of the same configuration and a description of the operations and effects are omitted for the sake of brevity. .

  FIG. 7 is a schematic diagram illustrating an overall configuration of a communication system according to the third embodiment. In the third embodiment, the ECU 1 includes a phase shift unit 5 that shifts the phase of the differential signal. Specifically, the ECUs 1 a, 1 c, and 1 d include the phase shift unit 5. Here, the phase shift unit 5 included in the ECU 1a and the ECU 1d is referred to as a first phase shift unit 5a, and the phase shift unit 5 included in the ECU 1c is distinguished from the second phase shift unit 5b. The first phase shifter 5a and the second phase shifter 5b shift the phase of the differential signal to different phases. That is, the phase shift amounts of the differential signals that are input and output by the ECUs 1a and 1d including the first phase shift unit 5a and the ECU 1c including the second phase shift unit 5b are different from each other. For example, the first phase shift unit 5a and the second phase shift unit 5b are configured such that one phase is a multiple of the other prime number. In the ECU 1 that does not include the phase shift unit 5, the phase shift amount of the differential signal to be input / output is zero. Moreover, the specific structure of the 1st phase shift part 5a and the 2nd phase shift part 5b is mentioned later.

  FIG. 8 is a block diagram showing the configuration of the ECU 1a. In the third embodiment, in the ECU 1a, the first phase shift unit 5a is interposed in two wiring patterns between the driver 16 and the connection unit 17. The first phase shift unit 5a includes two delay lines 51 interposed in each wiring pattern. The delay line 51 shifts the phase of the differential signal by delaying the differential signal input / output by the driver 16.

  Note that the ECU 1c having the second phase shifter 5b is different from the first phase shifter 5a in that the differential signal is delayed in the second phase shifter 5b, and has the same configuration as the ECU 1a. Therefore, the description is omitted. Further, the ECU 1d has the same configuration as the ECU 1a, and the ECUs 1b and 1e are the same as the configuration of the ECU 1 in the first and second embodiments described above, and thus the description thereof is omitted.

  In the communication system configured as described above, it is possible to suppress the influence of ringing that occurs when a differential signal transmitted from one ECU 1 is transmitted to another ECU 1. Hereinafter, an example in which the influence of ringing can be suppressed by the communication system according to Embodiment 3 will be described.

  When a differential signal is output from the central ECU 1b among the three ECUs 1a, 1b, and 1c connected in succession in FIG. 7, the differential signal is sent to both ends via the twisted pair wires 3b and 3c. The ECU 1a and the ECU 1c are reached. The differential signals that have reached the ECU 1a and the ECU 1c are partially reflected according to the degree of impedance mismatch and become reflected waves. For example, a reflected wave is generated at the connection portion 17 and the pair of terminals 16 a and 16 b of the driver 16. In general, the input impedance of the driver 16 is extremely higher than the characteristic impedance of the wiring pattern of the circuit board 18. Therefore, the degree of impedance mismatch becomes large, and most of the differential signals reaching the ECU 1a and the ECU 1c become reflected waves at the pair of terminals 16a and 16b. The reflected wave generated as described above reaches the ECU 1b via the twisted pair wires 3b and 3c (see the broken arrow in FIG. 7). At this time, when the reflected waves transmitted through the twisted pair wires 3b and 3c have the same phase, the amplitude of the combined wave increases and the influence of ringing increases.

  In the third embodiment, the first phase shift unit 5a included in the ECU 1a and the second phase shift unit 5b included in the ECU 1c are different in the degree of delaying the differential signal. That is, since the phases of the reflected waves are different from each other, the amplitude of the combined wave can be reduced compared to the case of the same phase, and the influence of ringing can be suppressed in communication between the ECU 1a, ECU 1b, and ECU 1c. . The differential signal output from the ECU 1b also reaches the ECUs 1d and 1e, and a reflected wave is generated similarly. In addition, although reflected waves are also generated in the terminal ECUs 2a and 2b, each terminal ECU 2 has a terminal circuit 27, so that the reflected waves have little influence on the ECU 1b.

  In addition, for all combinations that can be three ECUs 1 connected in series, at least one of them includes a phase shift unit 5, and the amount of shift of the phase of the differential signal input / output by the ECUs 1 at both ends is made different. The influence of ringing can be suppressed in the entire system. All combinations that can be three ECUs 1 connected in series are, for example, three sets of ECUs 1a, 1b, and 1c, ECUs 1b, 1c, and 1d, and ECUs 1c, 1d, and 1e in FIG. is there. In the set of ECUs 1b, 1c, and 1d, the ECU 1b does not include the phase shift unit 5, and the ECU 1d includes the phase shift unit 5. Therefore, the phase shift amounts of the differential signals input and output by the ECUs 1 at both ends are different. In the set of ECUs 1c, 1d, and 1d, the ECU 1c includes the phase shift unit 5, and the ECU 1e does not include the phase shift unit 5. Therefore, the phase shift amounts of the differential signals input and output by the ECUs 1 at both ends are different. In the communication system configured as described above, when each ECU 1 outputs a differential signal, the ECU 1 or the terminal ECU 2 connected to the output ECU 1 has a different phase shift amount of the differential signal to be input / output. The phase of the reflected wave is different. Therefore, the influence of ringing can be suppressed in the entire communication system.

  The communication system having the above configuration has a simple configuration and can suppress the influence of ringing. In the third embodiment, the configuration in which the phase of the first phase shift unit 5a, the second phase shift unit 5b, and the like is shifted is illustrated using a delay line. May be. For example, a resistor and a Schmitt trigger connected in series and a capacitor having one end connected between the resistor and the Schmitt trigger and the other end grounded may be used. Further, for example, a so-called gate delay including a plurality of logic gates may be used.

(Embodiment 4)
In the third embodiment, a configuration is used in which the phases of two types of differential signals of the first phase shifter 5a and the second phase shifter 5b are shifted. In the fourth embodiment, an example in which one type of phase shift unit 5 is used will be described. Since the other configurations and operations except the configurations and operations described below are the same as those in the above-described third embodiment, a detailed description of the same configurations and a description of the operations and effects are omitted for the sake of brevity.

  FIG. 9 is a schematic diagram illustrating an overall configuration of a communication system according to the fourth embodiment. In the communication system in FIG. 9, the ECUs 1a, 1b, and 1e include the phase shift unit 5, and the ECUs 1c and 1d do not include the configuration. The phase shift unit 5 includes a delay line and the like, similar to the phase shift units 5a and 5b. Here, among the four communication devices of the ECUs 1a to 1d connected in series, the differential signals to be inputted and outputted in each of the two sets of the ECUs 1a and 1b and the set of the ECUs 1c and 1d. The amount of phase shift is the same. At this time, in ECUs 1a to 1d, all combinations that can be three ECUs 1 connected in series are a set of ECUs 1a, 1b, and 1c and a set of ECUs 1b, 1c, and 1d. Since one of the ECUs 1 at both ends of each set of the three ECUs 1 includes the phase shift unit 5 and does not include the other, the phase shift amounts of the differential signals input and output by the both ends ECU 1 are different. Therefore, the influence of ringing in each set of three ECUs 1 connected in series can be suppressed. That is, the influence of ringing in the continuously connected ECUs 1a to 1d can be suppressed. In addition, the influence of ringing can be suppressed by only one type of phase shifter 5.

  Further, in all combinations that can be four ECUs 1 or terminal ECUs 2 connected in series, at least one set of two consecutive ECUs 1 or terminal ECUs 2 is made to have the same phase shift amount of input / output differential signals. Thus, the influence of ringing can be further suppressed.

  The communication system having the above configuration has a simple configuration and can suppress the influence of ringing. In addition, a communication system capable of suppressing the influence of ringing can be constructed by using only one type of phase shifter 5.

(Embodiment 5)
In the above-described third and fourth embodiments, the configuration for shifting the phase of the differential signal is provided in the ECU 1. In the fifth embodiment, an example provided in the connector 4 will be described. Since the other configurations and functions except the configurations and functions described below are the same as those in the third and fourth embodiments described above, a detailed description of the same configurations and a description of the functions and effects are omitted for the sake of brevity. .

  FIG. 10 is a block diagram illustrating a configuration of the male connector 42 according to the fifth embodiment. The male connector 42 includes a terminal 42a connected to each signal line included in the connected twisted pair wire 3 and a terminal 42c electrically connected to a pin of the female connector 41. The male connector 42 includes a delay element 42b interposed between the terminal 42a and the terminal 42c. The delay element 42b is configured by, for example, a delay line. The delay element 42b has a lead wire or the like, and the lead wire is connected to each of the terminal 42a and the terminal 42c by soldering, crimping, pressing, or the like.

  The phase of the differential signal output from the driver 16 can be shifted by connecting the male connector 42 thus configured to the female connector 41 and connecting the twisted pair wire 3 to the ECU 1. The two delay elements 42b connected to the terminal 42a to which the single twisted pair wire 3 is connected correspond to the phase shift unit in the present invention.

  Further, in the fifth embodiment, the ECU 1 connected to the male connector 42 described above does not include the phase shift unit 5 in the third and fourth embodiments.

  The communication system having the above configuration has a simple configuration and can suppress the influence of ringing, as in the third and fourth embodiments.

  In addition, although the communication system in Embodiments 1-5 showed the structure provided with five ECU1, other numbers may be sufficient.

  In addition, it should be considered that the embodiment disclosed this time is illustrative in all respects and not restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of claims for patent, and is intended to include all modifications within the scope and meaning equivalent to the scope of claims for patent.

1 ECU (communication device)
2 Terminal ECU (communication device)
DESCRIPTION OF SYMBOLS 3 Twisted pair line | wire 4 Connector 5 Phase shift part 5a 1st phase shift part 5b 2nd phase shift part 16 Driver 16a, 16b Terminal (1st terminal, 2nd terminal)
17 connection part 17a, 17b, 17c, 17d wiring pattern (first connection part, second connection part)
27 terminal circuit 41 female connector 42 male connector 42b delay element 43 connection portion 43a, 43b pin (first connection portion, second connection portion)

Claims (10)

Three or more communication devices connected in a daisy chain using a plurality of twisted pair wires in which a pair of signal wires are twisted together, and each of the three or more communication devices is connected to each of the connected twisted pair wires. A communication system for performing communication by inputting and outputting a differential signal represented by a difference between two applied voltages,
The communication device connected to the two twisted pair wires is
A first terminal to which one voltage representing the differential signal is to be applied;
A second terminal to which the other voltage representing the differential signal is to be applied;
One signal line in one of the twisted pair lines, one signal line in the other twisted pair line, and a first connection portion that electrically connects the first terminal;
A communication system, comprising: another signal line of the one twisted pair line, another signal line in the other twisted pair line, and a second connection portion that electrically connects the second terminal. The communication system according to claim 1, wherein the first connection part and the second connection part are wiring patterns formed on a circuit board. The communication system according to claim 2, wherein the first connection portion and the second connection portion are wiring patterns formed on different surfaces of the circuit board. The communication system according to any one of claims 1 to 3, wherein at least one of the communication devices includes a phase shift unit that shifts a phase of a differential signal to be input and output. There are four or more communication devices,
Of the three communication devices connected in series, at least one of the two communication devices at both ends includes the phase shift unit,
The communication system according to claim 4, wherein the phase shift amounts of the differential signals input / output to / from the two communication devices at both ends are different from each other. Of the four communication devices connected in series, at least one set of two continuous communication devices is configured such that the phase shift amounts of the differential signals input to and output from each other coincide with each other. The communication system according to claim 5. The terminal communication device includes a terminal circuit interposed between a pair of signal lines constituting a connected twisted pair line. Communications system. Three or more communication devices connected in a daisy chain using a plurality of twisted pair wires in which a pair of signal wires are twisted together, and each of the three or more communication devices is connected to each of the connected twisted pair wires. A communication system for performing communication by inputting and outputting a differential signal represented by a difference between two applied voltages,
Each of the communication devices connected to the two twisted pair wires includes a first terminal to which one voltage representing the differential signal is to be applied and a second terminal to which the other voltage is to be applied,
A communication device connected to the two twisted pair wires, and a connector interposed between the two twisted pair wires,
The connector is
One signal line in one of the twisted pair lines, one signal line in the other twisted pair line, and a first connection portion that electrically connects the first terminal;
A communication system, comprising: another signal line in the one twisted pair line, another signal line in the other twisted pair line, and a second connection part that electrically connects the second terminal. At least one of the connectors is
The communication system according to claim 8, further comprising a phase shift unit that shifts a phase of a differential signal input and output by the connected communication device. In a communication device to be connected to two twisted pair wires in which a pair of signal wires are twisted together,
A first terminal to which one voltage representing a differential signal is to be applied;
A second terminal to which the other voltage representing the differential signal is to be applied;
One signal line in one twisted pair line, one signal line in the other twisted pair line, and a first connection part to electrically connect the first terminal;
A communication apparatus comprising: the other signal line in the one twisted pair line; the other signal line in the other twisted pair line; and a second connection unit to electrically connect the second terminal.

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