JPH0556084A - Data transmission method for communication controller - Google Patents

Abstract

PURPOSE:To enhance the reliability of data transmission in the communication controller by sending newest data with high necessity quickly. CONSTITUTION:After data in an input port 21 are stored once in a transmission buffer memory, the data are sent from a communication control section 26 to a multiplex bus MB in the data transmission method for the communication controller and a data change in the input port 21 is detected by a port control section 23. When the data change is detected, while the data stored in a transmission buffer memory 24 are being sent again, the port control section 23 stops the storage of the changed newest data to the transmission buffer memory 24. In the state of transmission wait in which the data transmission is not implemented even once, the newest data are stored in the transmission buffer memory 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control device connected to a multiplex transmission line for transmitting a message, and more particularly to a data transmission method of the communication control device for transmitting data.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a multiplex node having a communication control device of this type has a communication control device (LSI) 11 connected to a multiplex transmission line (multiplex bus) MB composed of paired wires or the like. And a control circuit (CPU) 12 and an input / output interface (I / F) circuit 13. The CPU 12 takes in events (data) from various switches and the like via the I / F circuit 13, and the LSI 11 makes C
It has a transmission buffer memory for storing the data of the message input from the PU 12 and a data ID for identifying the data, and transmits the message of the transmission buffer memory to the multiplex bus MB. Some multi-nodes having an LSI for communication control do not have a CPU. In this case, after storing the data and data ID fetched via the I / F circuit 13 in the data buffer memory,
It was stored in the transmission buffer memory and transmitted to the multiplex bus MB. These multiple nodes are connected to multiple buses to form a network, and CSMA / CD (Carrier Sense Multiple
It is used, for example, for multiplex transmission of data in an automobile using the Access / Collision Detection) transmission method. At the node where the event has changed, the CPU 12
The transmission data is written in the transmission buffer memory 11 to generate a transmission request. The LSI 11 receiving the transmission request starts transmitting the transmission data, and the CPU 12 causes the LSI 1 to
After the transmission of 1 is completed and the transmission buffer memory becomes empty, the next transmission data can be written.

FIG. 7 is a diagram showing an embodiment of a message format of a data frame transmitted between multiple nodes. In the figure, the data frame includes a SOM (Start Of Message) that indicates the beginning of a message and a priority (PRI) that determines the priority when multiple multiple nodes simultaneously transmit data to multiple buses.
And a message ID indicating the content of each data (DATA) that follows, a control data area (CONT) containing data indicating the data length, and a length indicated by CONT (variable length)
Data area (DATA1 to DATA4), error check code such as CRC, and EOD (End Of Dat) that indicates the end of the data
a), an ACK signal area for returning an ACK signal from all the multiple nodes in a bit-corresponding manner, and a 1-bit ACK confirmation area indicating that the ACK signal has been returned from all the registered nodes and the data transmission is completed. And an EOM (End Of Message) indicating the end of the message.

Here, as shown in FIG. 8, the transmission multiplex node transmits a data frame composed of SOM to EOD via a multiplex bus, and the other multiplex nodes receive data normally without error. Returns an ACK signal to a predetermined ACK signal area. When the basic multiplex node having the ACK management function confirms that the ACK signals have been returned from all the registered nodes, it sends the dominant ACK confirmed bit to the ACK confirmed area. In FIG. 8, the transmitting multi-node A and the receiving multi-node E correspond to basic multi-nodes, and the receiving multi-nodes B, C and D are simple multi-nodes having no ACK management function. If there is no ACK returned from the receiving multiplex node B, the transmitting multiplex node A does not send the ACK confirmation bit and retransmits the data frame. This retransmission operation ends after a certain number of times, for example, X times, and if the registration of the receiving multi-node B is deleted, a certain node fails and an ACK
If the signal is not sent back, the retransmission will not be repeated indefinitely. When the simple multiplex node transmits a data frame, when the ACK confirmation bit is received, it is judged that the data transmission is normally performed and the transmission is terminated, and when the ACK confirmation bit is not received, the transmission is performed. It is judged that an error has occurred and retransmission is performed. This resend operation is
Similarly, it ended in X times.

Also, when new data to be transmitted is generated before the transmission is completed, there is a device which can cancel the transmission request of the data already written in the transmission buffer memory and can write the new data. is there.

[0006]

However, in the above-mentioned conventional example, when the data stored in the transmission buffer memory is in the transmission waiting state, the data in the transmission buffer memory is transmitted even if the event changes. The latest data cannot be sent until later. For example, in the case of data transmission in an automobile, when the data of wiper on is stored in the transmission buffer memory, even if the data of the horn changes from off to on, the data of the wiper on in the transmission buffer memory is transmitted. Only after that, the latest horn-on data cannot be transmitted, and there is a problem that the transmission of the latest data with higher necessity is delayed.

Further, there is a problem that if the transmission request for the data already stored in the transmission buffer memory is canceled, the data is lost. for that reason,
There is a problem that a buffer memory for the queue is required and the cost is increased. If a transmission error occurs during the transmission of a certain message and the transmission request is canceled while the message is being retransmitted, the data held by the node will differ between the node that could receive the message and the node that could not. There was a problem that it would end up.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a data transmission method of a communication control device capable of rapidly transmitting the latest data with high necessity.

[0009]

In order to solve the above-mentioned object, the present invention has a transmission storage means connected to a multiplex transmission line and storing data of a message to be transmitted to the multiplex transmission line. In the data transmission method of the communication control device for temporarily storing the input data in the transmission storage means, and then transmitting the data to the multiplex transmission path, when the change of the input data is detected and the change of the data is detected, Retransmission of the data stored in the transmission storage means is detected, and storage of the changed data in the transmission storage means according to the detection result of the retransmission is performed. A method for transmitting data in a communication control device that stops until transmission is completed is provided.

[0010]

When the data stored in the transmission storage means including the transmission buffer memory is being retransmitted, the storage of the changed latest data in the transmission storage means is stopped. It is possible to store the above data in the transmission storage means. Therefore, it is possible to quickly transmit the most necessary and latest data without the data between the nodes on the network being different, and to improve the reliability of data transmission in the communication control device.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings of FIGS. FIG. 1 is a configuration block diagram showing the configuration of a communication control device according to the present invention. In this figure, a simple multi-node without a CPU and without an ACK management function is shown. In the figure, the input port 21 takes in data from various switches and the like as parallel signals, as in FIG. The communication control device comprises an input port 21, an output port 22, a port control unit 23, a transmission buffer memory 24 for storing transmission data, a reception buffer memory 25 for storing received data, and a communication control unit 26. The node shown in this embodiment has only one type of transmission ID, and the content of the transmission frame is as shown in FIG. That is, the transmission ID is data that identifies the node, and 1 bit of the data area corresponds to 1 port of the input port. When the number of input ports changes even one port, the data of all ports is latched, the data of the input port A is in the area of DATA1, and the data of the input ports B, C and D is DATA2, respectively.
It is stored and transmitted in the areas 3 and 4.

The port controller 23 detects a change in the parallel data input from the input port 21, and sets an input port change flag when the input data changes. When there is a change in the input data, the communication control unit 26 stores the data in the transmission buffer memory 24 only when the flag indicating that the data is being retransmitted is checked in the communication control unit 26.
Request to send. Further, the port control unit 23 outputs the data stored in the reception buffer memory 25 by the communication control unit 26 to the output port 22.

When receiving the transmission request, the communication control unit 26 detects the idle state of the multiplex bus MB, and when the multiplex bus MB is in an idle state where no multiplex node is used, the transmission buffer memory 24 Data in the multiplex bus M
When the transmission is performed via B and the transmission is completed, the dominant ACK confirmation bit transmitted to the multiplex bus MB from the basic multiplex node having the ACK management function is received, and the AC
It is determined whether or not the data stored in the transmission buffer memory 24 needs to be retransmitted according to the presence or absence of the K confirmation bit.
When retransmission is unnecessary, the retransmission flag is turned off. Further, when the communication control unit 26 receives the data of the frame as shown in FIG. 7 via the multiplex bus MB, the communication control unit 26 stores the received data in the reception buffer memory 25.

FIG. 2 is a diagram showing the contents of the transmission frame transmitted by the communication control device as described above, and the state "abcdefgh" of the input port A is "0000000".
When changing from "0" to "10000000", the data of all ports A, B, C, D are latched and stored in the transmission buffer memory 24, and a transmission request is generated.
When the multi-bus MB is busy and waiting for transmission, port b
Data changes and the status of input port A changes to "11000".
000 ”, the new data“ 1100000 ”
Since 0 ″ is stored in the transmission buffer memory 24, the communication control unit 26 can transmit the latest data in one frame. When there are a plurality of types of transmission IDs, the data of different transmission IDs change. Therefore, it is necessary to prepare a plurality of transmission buffer memories to prepare for transmission waiting. However, in the present embodiment, since there is only one type of transmission ID,
The latest data can be sent by preparing one send buffer memory, discarding the data waiting to be sent, and sending only new data.

Next, the data transmission operation of the communication control device shown in FIG. 1 will be described with reference to the drawings of FIGS. First, the port control unit 23 detects whether or not the input port change flag of the input port 21 is set (step 101). Here, when the flag is not set, the input data from the input port 21 does not change, and thus the standby state is set until the data changes. If the flag is set, the input data has changed, so the data (parallel data) is latched as transmission data (step 102). At this time, the communication control unit 26 detects the idle state of the multiplex bus MB (step 103).

Here, when the multiplex bus MB is in an idle state where no multiplex node is used, the port control section 23 stores the latched data in the transmission buffer memory 2.
4 and issues a transmission request to the communication control unit 26. Upon receiving the transmission request, the communication control unit 26 transmits the SOM of the transmission data in the transmission buffer memory 24 to the multiplex bus MB to fix the transmission data (step 104), and then from the PRI to EOD shown in FIG. Then, the data frame is transmitted (step 105). Then, it is determined whether there is a competition loss with another node (step 106).

Here, if there is no loss of competition with other nodes, the communication control unit 26 transmits the data frame, and then, A is placed in a predetermined ACK area as shown in FIG.
The CK signal is transmitted (step 107), and it is determined whether the ACK confirming area for storing the ACK confirming bit transmitted by the basic multiplex node having the CPU is dominant (step 108).

If the ACK confirmation area is dominant, the flag indicating that retransmission is in progress in the communication control unit 26 is turned off, and the number of retransmissions provided in the communication control unit 26 is counted. The count value of the retransmission counter is cleared (step 109), the process returns to step 101, and it is determined whether the input port change flag is set. If the ACK confirmation area is in the passive state, it is determined that the transmission data is to be retransmitted, the retransmission flag is turned on (step 110), and the count value of the retransmission counter is set to 1.
After the addition (step 111), it is judged whether or not the retransmission has been completed X times (step 112).

Here, the communication control device determines that the re-transmission is X
When the transmission is completed, the process returns to step 101 to perform the same operation as above. When the retransmission is not completed X times, the process returns to step 103 to detect the idle state of the multiplex bus MB, When the bus MB becomes empty, the data in the transmission buffer memory 24 is retransmitted. If the multiplex bus MB is in use in step 103,
Alternatively, if the competition is lost in step 106 (the communication control device enters the reception state), the transmission data in the transmission buffer memory 24 is transferred to the communication control unit 26 as shown in FIG.
Is being retransmitted by the retransmission flag (step 113). If the above flag is off, the transmission data is not being retransmitted, and the input port change flag is set (step 114), the transmission is performed. Since there is a change in data (input of new transmission data), the transmission data is latched from the input port 21 (step 115).

When the retransmission flag is set in step 113 and the transmission data is being retransmitted, the input port change flag is not set in step 114, or the transmission data is latched in step 115, Returning to step 103, the idle state of the multiplex bus MB is detected. Therefore, in this embodiment, it is determined by the retransmission flag whether the latest data from the input port 21 is stored in the transmission buffer memory 24, and only when the data stored in the transmission buffer memory 24 is being retransmitted, Transmission buffer memory 2 of changed latest data
4 is stopped, the latest data is stored in the transmission buffer memory 24 after the retransmission is completed, and the data stored in the transmission buffer memory 24 is not transmitted at all, and in the waiting state for transmission, It becomes possible to store the latest data in the transmission buffer memory 24. Therefore, it is possible to quickly send the latest data that is highly necessary.

In the case where the node which can receive the message being retransmitted and the node which cannot receive the message may have different data, or the highest priority data has occurred. In this case, since the data may be stored in the transmission buffer memory 24 even during the retransmission, whether the latest data changed during the retransmission is stopped to be stored in the transmission buffer memory 24 is determined by, for example, an external terminal. If it can be set, it will be more versatile.

In this embodiment, the case where the data transmission method according to the present invention is used for a multi-node having no CPU has been described, but the present invention is not limited to this, and may be used for a multi-node having a CPU. It is possible.

[0023]

As described above, according to the present invention, there is provided the transmission storage means for storing the data of the message which is connected to the multiplex transmission line and which is to be transmitted to the multiplex transmission line, and the input data is transmitted by the transmission. In the data transmission method of the communication control device, which temporarily stores in the storage means and then transmits to the multiplex transmission path, the change in the input data is detected, and when the change in the data is detected, the transmission storage means is stored. Retransmission of the stored data is detected, and storage of the changed data in the transmission storage means according to the detection result of the retransmission is performed until the retransmission of the data stored in the transmission storage means ends. Since it is stopped, the latest data with high necessity can be transmitted quickly, and the reliability of data transmission in the communication control device can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of a communication control device for explaining a data transmission method according to the present invention.

FIG. 2 is a diagram showing the contents of a transmission frame transmitted by the communication control device shown in FIG.

FIG. 3 is a diagram showing a flowchart for explaining a transmission operation of the communication control device shown in FIG.

FIG. 4 is a diagram showing a flowchart for explaining a transmission operation of the communication control device shown in FIG.

5 is a diagram showing a flowchart for explaining a transmission operation of the communication control device shown in FIG.

FIG. 6 is a configuration diagram showing a schematic configuration of a multi-node.

FIG. 7 is a diagram showing a structure of a frame of a signal transmitted between multiple nodes.

FIG. 8 is a diagram for explaining data transmission between multiple nodes.

[Explanation of symbols]

 11 communication control circuit (LSI) 12 control circuit (CPU) 13 input / output interface (I / F) circuit 21 input port 22 output port 23 port control unit 24 transmission buffer memory 25 reception buffer memory 26 communication control unit MB multiplex transmission line ( (Multiple buses)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshikazu Nobutoki, 3-1, Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Inventor Hiroaki Sakamoto 3-3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Within the corporation

Claims (2)

[Claims] 1. A transmission storage unit, which is connected to a multiplex transmission line and stores data of a message to be transmitted to the multiplex transmission line, wherein after input data is temporarily stored in the transmission storage unit, In the data transmission method of the communication control device for transmitting to the multiplex transmission path, the change of the input data is detected, and when the change of the data is detected, the retransmission of the data stored in the transmission storage means is detected. A communication control characterized in that the storage of the changed data in the transmission storage means in accordance with the detection result of the retransmission is stopped until the retransmission of the data stored in the transmission storage means is completed. Device data transmission method. 2. The storage of the changed data in the transmission storage means is set to be stopped or not stopped until the retransmission of the data stored in the transmission storage means is completed. Item 1. A data transmission method of the communication control device according to Item 1.