JP2936671B2 - Communication device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device, and more particularly, to a communication device that forms one station of a multiplex transmission network that multiplexes a communication line and transmits information.

[Prior Art] Conventionally, a network in which a plurality of communication devices (hereinafter, referred to as nodes) multiplex communication lines and communicate with each other,
For example, a multiplex transmission system for a vehicle in which a master node as a central station and a plurality of slave nodes communicating only with the master node perform serial bidirectional communication via a communication line multiplexed by a time division method. It has been known.

In this type of multiplex transmission system, each slave node is connected to external devices such as various switches and actuators, and outputs an operation signal to the external device according to operation information transmitted from the master node. In addition, when an input signal from an external device changes, normal transmission for transmitting information about the signal state to the master node is performed, and the signal state information transmitted in the immediately preceding normal transmission is periodically transmitted to the master node. Backup transmission is also performed to re-transmit and inform that the own station is operating normally. On the other hand, the master node collects and processes information from each slave node, and transmits operation information to each slave node.

As described above, since transmission frequently occurs between the master node and each slave node and contention may occur, in a multiplex transmission system, transmission priorities are generally determined in advance, and priority is given to transmission priorities. The communication order is maintained by giving priority to the transmission of the node with the higher rank.

[Problems to be Solved by the Invention] However, in the multiplex transmission system, when a slave node having a lower priority transmits signal state information and collides with backup transmission of a slave node having a higher priority, the latter transmission is performed. Priority is given to the former, and the former transmission is delayed, so it takes time for information collection and processing at the master node, and as a result, the transmission of operation information from the master node to the slave node is delayed, and operation of external devices is delayed. There was a problem.

Therefore, an object of the present invention is to provide a communication device capable of transmitting information quickly.

Means for Solving the Problems The gist of the present invention is that a communication line is multiplexed to constitute one station of a multiplex transmission network for transmitting information, and mutual transmission between other stations collides. A communication device in which priorities in a multiplex communication network regarding which station is to be prioritized when contention occurs are determined in advance in said multiplex communication network, and said first priority information setting means sets said priority information. Second priority information setting means for setting information of a priority lower than the predetermined priority of another station; detection means for detecting a change in the state of a signal input from an external device; A first transmitting unit that, when a change in the state of the signal is detected by the unit, transmits the state information indicating the change state by adding the priority information set by the first priority information setting unit; By means A second transmission in which, at a predetermined time during which no change in the signal state is detected, the priority information set by the second priority information setting means is added to the operation information indicating the operation state of the own station and transmitted. Means for determining when the contention occurs during transmission by the first or second transmitting means, the level of the priority of the own station and the priority of the other station which is the partner of the transmission collision; Communication stopping means for stopping transmission of the first or second transmitting means when the priority of the own station is determined to be lower than the priority of the other station by the means. In the device.

[Operation] According to the communication device of the present invention configured as described above,
The second transmission means transmits the operation information indicating the operation state of the own station with priority information lower than the priority of the other station added to the operation information at a predetermined time while the detection means does not detect a change in the state of the signal. At this time, when contention occurs, the determination unit determines that the priority of the own station is lower than the priority of the other station that is the transmission collision destination. Then, the transmission stopping means stops the transmission of the second sending means.

Therefore, in a multiplex transmission network including a plurality of communication devices having the above-described configuration, when contention occurs, transmission of status information of another station is always given priority over transmission of operation information of the own station, and transmission of status information of another station is always performed. The transmission of the status information of the own station always takes priority over the transmission of the operation information.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

First, FIG. 1 is a block diagram showing a configuration of a communication apparatus according to an embodiment to which the present invention is applied, FIG. 2 is a block diagram of a local area network (hereinafter simply referred to as a network), and FIG. FIG. 4 is an explanatory diagram illustrating a configuration of a message to be transmitted.

As shown in FIG. 2, the network NW includes a central communication device 3 and a plurality of communication devices 5 connected to one system of communication line W, and is generally called a bus network. In this network NW, the communication line W is multiplexed by a time division method, and serial bidirectional communication is performed by a pulse width modulation method (PWM).

The central communication device 3 is called a master node and communicates with an arbitrary communication device 5, and each communication device 5 is called a slave node and communicates only with the central communication device 3. For example, when mounted on a vehicle, status information from various switches SW of each part of the vehicle is transmitted from each communication device 5 to the central communication device 3, and various command information is transmitted from the central communication device 3 to each communication device 5, and the actuator is AC is operated.

Further, in the network NW, the communication proceeds in accordance with a predetermined communication procedure (for example, the communication procedure J1850 of the American Society of Automotive Engineers of Japan), and the priority when contention occurs (to be described later) is maintained so that the communication order is maintained. It is predetermined. Further, the message is transmitted in a fixed configuration and format. For example, as shown in FIG. 3, the transmission control character SOM indicating the beginning of the message, the priority information PRI, the code numbers ID of the transmission destination and the transmission source, the text data D1 to Dn, the error detection code CRC, and the end of the message. It comprises a transmission control character EOM shown, a transmission control character IMS for synchronizing between stations, and the like.

The central communication device 3 includes a well-known CPU 3a, a ROM 3b, a RAM 3c, a serial communication controller 3d and the like and has a judgment processing capability, and communicates with each communication device 5. In addition,
The central communication device 3 is well-known as a serial communication control device, and thus details are omitted.

Next, as shown in FIG. 1, each communication device 5 includes a communication control circuit 10 for controlling transmission and reception, and a change detection signal when a signal input from various external switches SW to the input circuit 12 changes.
An input monitor circuit 14 for outputting Ssg, a timer circuit 16 for outputting a periodic signal Sti at a predetermined cycle, and a change detection signal Ssg from the input monitor circuit 14 or a preset according to the periodic signal Sti from the timer circuit 16 Priority information PRI or
A priority information setting circuit 18 that outputs PRIα to the communication control circuit 10, and a transmission shift register 20 that converts parallel information from the communication control circuit 10 and the input circuit 12 into serial information.
A communication interface circuit 22 that performs serial transmission / reception and arbitration (described later); a reception shift register 24 that converts serial information from the communication interface circuit 22 into parallel information; and a latch circuit that latches parallel information from the reception shift register 24. External actuator AC
And a clock supply circuit 28 for supplying a clock signal to each of the units 10 to 26.

In this embodiment, the priority information setting circuit 18 corresponds to the first and second priority information setting means, and the communication interface circuit 22 corresponds to the determination means.

When the change detection signal Ssg is input from the input monitor circuit 14, the communication control circuit 10 transmits the information D1 to Dn indicating the signal state of the switch SW from the input circuit 12 as text data to the transmission shift register 20 and the communication control circuit 10. Interface circuit
22 (hereinafter referred to as normal transmission). Further, when the periodic signal Sti is input from the timer circuit 16, the central communication device 3 instructs that the own station is operating normally by instructing retransmission of the signal state information D1 to Dn transmitted in the immediately preceding normal transmission. (Hereinafter referred to as backup transmission).

On the other hand, at the time of reception, the character ID and CRC input via the communication interface circuit 22 and the reception shift register 24 are checked to check the code numbers and check for code errors.

The timer circuit 16 outputs a periodic signal Sti to the communication control circuit 10 at a predetermined cycle, and its time count is reset by a reset signal Sre from the communication control circuit 10 at the end of the normal communication.

When the change detection signal Ssg is input from the input monitor circuit 14, the priority information setting circuit 18
When the periodic signal Sti is input from the timer circuit 16, the predetermined priority information PRIα lower than the other stations is output to the communication control circuit 10, respectively.

Here, an example of the priority order in a network having one central communication device 3 and three communication devices 5 is shown in Table 1. In this network, in order to identify each station, the central communication device 3 is called a node 0, and each of the communication devices 5 is called a node 1, a node 2, and a node 3, and the smaller the value of the priority information, the higher the priority. Stipulated. The numerical value is
Represented in hexadecimal.

At the time of transmission, the communication interface circuit 22 uses SOM and EOM / IMS as a symbol / bit pattern at the beginning and end of the transmission, and converts the serial information from the transmission shift register 20 into a pulse width-modulated bit pulse. Send to

Further, the communication interface circuit 22 monitors the presence or absence of contention simultaneously with the transmission. That is, when transmitting the character PRI (PRIα), every time the own station transmits a bit pulse, it is determined whether or not the level of the communication line W is high when the level of the bit pulse is low. If the priority of the own station is lower or higher than that of the partner station (arbitration), and if the priority of the own station is lower than the partner station (the level of the communication line W is High), the transmission stop request signal Sst is transmitted. Output to the control circuit 10. In addition,
The decision logic is wired or logic,
The details are described in J1850, and are omitted.

 Next, the operation of the communication device 5 will be described.

At the time of normal transmission, the communication control circuit 10 receives a detection signal Sid from the communication interface circuit 22 indicating that the communication line W is idle and in an idle state (IDLE).
First, transmission of the character SOM is instructed to the communication interface circuit 22. Next, the communication control circuit 10 transmits the character PRI
The ID and the character CRC are added before and after the signal state information D1 to Dn (text data), output from the transmission shift register 20 to the communication interface circuit 22, and instruct the communication interface circuit 22 to transmit. Finally,
The communication control circuit 10 instructs transmission of the characters EOM and IMS.

Then, when a transmission end signal is input from the communication interface circuit 22, the communication control circuit 10 enters a receiving state.

The message is transmitted to the central communication device 3 in this manner. When contention occurs in the transmission process and the communication interface circuit 22 determines that the priority of the own station is lower than that of the other station, the communication interface circuit 22 The transmission stop request signal Sst is input from the
A value of 0 instructs the communication interface circuit 22 to switch from transmission to reception, and stops transmission.

At the time of backup transmission, predetermined priority information PRIα lower than the other stations is used instead of the priority information PRI, and the signal state information D1 transmitted in the immediately preceding normal transmission as text data.
To Dn form a message, respectively, and are transmitted to the central communication device 3 in the same manner as the normal transmission.

If contention occurs during this transmission process,
The priority of the own station is the priority of all other stations (normal transmission)
Since it is lower, the communication interface circuit 22 outputs the transmission stop request signal Sst to the communication control circuit 10. Then, the communication control circuit 10 instructs the communication interface circuit 22 to stop transmission and stops transmission. Further, when a collision occurs with the backup transmission of another station, the priority of the backup transmission is also determined, so that transmission continuation or transmission stop is determined according to the priority.

On the other hand, during reception, when a detection signal indicating that the symbol / bit pattern of the character SOM has been detected is input from the communication interface circuit 22, the communication control circuit 10 instructs the communication interface circuit 22 to receive. When the character ID is transferred via the reception shift register 24, the communication control circuit 10 determines whether or not the received code number matches the code number of the own station. Then, the communication interface circuit 22 is instructed to receive the information (if the code numbers do not match, the reception stop is instructed). Then, the text data D1 to Dn are input to the reception shift register 24, and the text data D1 to Dn and the character CR are input to the communication control circuit 10.
When C is transferred, the communication control circuit 10 checks the character CRC, and if no error is detected, the text data D1.
受 信 Dn is instructed to output to the shift register 24 via the latch circuit 26 to the actuator AC. Thereafter, the reception state is continued until the next transmission.

When the backup transmission is performed together with the normal transmission from each communication device 5 to the central communication device 3 in this way, the central communication device 3 issues various commands to each communication device 3 based on the transmitted signal state information D1 to Dn. Transmit to operate actuator AC.

Further, the central communication device 3 checks the signal state information D1 to Dn sent in the backup transmission and the signal state information D1 to Dn sent in the immediately preceding normal transmission, and determines whether or not they match. Is checked, the reliability of the received data is increased, and whether or not each communication device 5 is operating normally is determined by determining whether or not backup transmission is performed periodically. That is, the central communication device 3 monitors the operation state of each communication device 5 and increases the reliability of the received data by the backup transmission from each communication device 5.

As described above, in the present embodiment, since each communication device 5 performs backup transmission with a priority lower than the priority of other stations (during normal transmission), normal transmission of each communication device 5 performs backup transmission of another station. If there is a collision with the transmission, priority is given.
Therefore, each communication device 5 can immediately transmit a change in the state of the switch SW to the central communication device 3.

Therefore, even in the central communication device 3, each communication device 5
Since the collection and processing of the signal state information from the AC is quickly performed, the command information to the actuator AC can be transmitted to each communication device 5 without delay. Therefore, the operation of the actuator AC is not delayed as in the related art.

Here, in this embodiment, as shown in Table 1, the priorities of the nodes 1 to 3 at the time of backup transmission are set in the same order as the order of the order at the time of normal communication. May be set as follows. That is, the priority of the node 3 during normal transmission is set lower than that of the nodes 1 and 2, but the priority of backup transmission may be set higher than that of the nodes 1 and 2.

By setting the priorities at the time of backup transmission in this way, for example, the number of normal transmissions (per unit time) in the node 3 is smaller than that of the nodes 1 and 2, but the backup transmission needs to be performed in a shorter cycle. In such a case, the communication efficiency is improved.

Further, in the present embodiment, the communication device 5 is configured to periodically perform backup transmission, but may be configured to perform backup transmission in response to a transmission request from the central communication device 3. Alternatively, in addition to the periodic backup transmission, when the input signal from the outside changes, the normal transmission may be performed and the backup transmission may be performed a predetermined number of times following the normal communication.

[Effects of the Invention] As described above, according to the present invention, when transmitting operation information indicating the operation state of the own station, priority information lower than the priority of other stations is added and transmitted. When a contention occurs, the transmission of the status information of the other station is always given priority over the transmission of the operation information of the own station, and the transmission of the status information of the own station is always given priority over the transmission of the operation information of the other station. .

 Therefore, the transmission of the state information is performed quickly.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a communication device according to an embodiment, FIG. 2 is a block diagram illustrating a configuration of a network, and FIG. 3 is an explanatory diagram illustrating a configuration of a message. 3 central communication device, 5 communication device 10 communication control circuit, 16 timer circuit 18 priority setting circuit 22 communication interface circuit NW network W communication line

Claims (1)

(57) [Claims] 1. A multiplex transmission network for multiplexing communication lines and transmitting information, wherein one of the stations is given priority when contention occurs in which transmissions conflict with each other. A first priority information setting means for setting the priority information, wherein the first priority information setting means sets the priority information, and Second priority information setting means for setting low-priority information; detecting means for detecting a change in the state of a signal input from an external device; First transmission means for adding the priority information set by the first priority information setting means to the state information indicating the change state and transmitting the information; and a predetermined state while the state change of the signal is not detected by the detection means. Time A second transmitting means for adding the priority information set by the second priority information setting means to the operating information indicating the operating state of the own station and transmitting the added information; When contention occurs at the time of transmission, determining means for determining the level of the priority of the own station and the priority of the other station which is the partner of the transmission collision; and determining the priority of the own station by the determining means. A communication stopping means for stopping the transmission of the first or second transmitting means when it is determined that the order is lower than the ranking.