JPH0495429A - Multiplex communication equipment - Google Patents

Abstract

PURPOSE:To save a memory capacity for a common data or the like by using two signals as a data identification signal and a node priority signal to manage a bus. CONSTITUTION:When a data is sent to each node in the reception enable state, a reception data is sent to a data reception circuit 15 via a bus BS input output interface 14, in which an error is checked and a data ID code DID and a main data DT are extracted from a data frame signal and they are inputted to a data buffer control section 11. The control section 11 checks whether or not a same data as the code DID is registered in a data buffer 21 and stores the inputted code DID and main data DT to the buffer 21 when the same code is in existence and inputs a data reception request designating the code DID to a communication control section 50. When the same code DID is not in existence according to the comparison above, the received data frame signal is aborted.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a multiplex communication device applied to in-vehicle communication such as automobiles and construction vehicles, or in-machine communication in industrial machinery, and particularly relates to a multiplex communication device that is applied to in-vehicle communication such as automobiles and construction vehicles, or in-machine communication in industrial machinery. The present invention relates to a distributed multiplex communication device in which controllers (nodes) are distributed and information is exchanged between the plurality of nodes.

[Conventional technology]

With recent advances in electronic control technology, many microcomputers have been introduced into vehicles, especially automobiles, contributing to improved performance and comfort. On the other hand, however, in these systems, the wiring between sensors, switches, controllers, and actuators is routed separately for each system, so as the number of advanced functions increases, the space and weight increase, and the design becomes more complicated. - Complicated maintenance and inadequate means of exchanging information between controllers have become problems. Therefore, attempts were made to solve these problems by applying the multiplex communication system that is already widespread in offices.
Several systems have been proposed and put into practical use.

One of these systems is CAN (Control
There is an in-vehicle multiplex communication system as shown in FIG. 6, which is known as an in-vehicle area network. In this system, several controllers (nodes) are arranged for each of the body electrical system, self-diagnosis system, power train, brake, and suspension system, and a node is connected between these multiple nodes. . This system uses a data frame signal as shown in FIG. 5 as a communication protocol.

DID, data identification coat (data ID coat) DL
, data length code DT, data body ERRCRC, error check code data ID2)" DI D is used to identify the message content (data name) of the data frame signal.
This data ID code DID also serves to identify the priority order of bus use.

In this case, the lowest number 00/0 has the highest priority, and as the number increases, the priority decreases.

Furthermore, in this CAN system, each node constantly monitors the bus and starts transmitting itself when the bus becomes free. On this occasion,
Since it is a multi-access method, multiple nodes can access the lot at the same time, and when there is simultaneous access, the data ID code D at the beginning of the data frame signal is
They compete for the right to use by comparing IDs (priorities) bit by bit. On the CAN lotus, it is "0" or dominant,!・
If there is a collision between "0" and "]" on the bus, the signal on the bus will be "0" and "]".
Since it has been pulled down so that it becomes 0,
After all, the data I of the message being sent to the bus at that time
Among D, only the one with the highest priority remains, and the others are destroyed. Since each node monitors the bus, this mechanism allows it to know if there is a message on the bus that has higher priority than its own, and if so, it can take over as the receiver. Therefore, among the messages sent, only the one with the highest priority is sent to the end.

Furthermore, in the CAN system, a message is sent to all notes, and the receiving side determines whether the message is a necessary message or not.

Which message to import is determined by registering a required data ID in each note when each node is initialized.

That is, the data ID registered with each note is compared with the message on the bus, and only messages that match are taken in, and unnecessary messages are discarded.

[Problem to be solved by the invention]

In this way, in this CAN system, data transmission arbitration is controlled based on priority using the data ID code DID. This arbitration method is suitable for real-time control systems such as those for vehicles that require high responsiveness because the responsiveness of high-priority data does not deteriorate even if the communication load increases.

However, in this CAN system, if there is data that is commonly used across multiple notes, the following inconvenience will occur. In other words, if the same data ID code DID is assigned to each common data across multiple nodes, if multiple nodes send out data frame signals with the same data ID code DID, the data frame signals will be completely identical. Data with priority will be sent out at the same time, and the data content will no longer be guaranteed.

In addition, for these common data, a separate ID is provided for each note.
When assigning codes, MXN ID codes are required for M nodes and N common data, and ID
Managing codes becomes troublesome and complicated, and these IDs
There is a problem that the storage area for the code increases.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a multiplex communication device that can facilitate the management of common data and reduce the common data storage area.

[Means to solve the problem]

In the present invention, in a multiplex communication device in which a plurality of nodes are connected to a bus in which one of the binary signal levels is given priority, and multiplex communication is performed between the plurality of nodes,
Each of the nodes transmits a data frame signal including a data identification signal indicating a data name and the priority of the data, a node priority signal indicating the priority of the node, and data; bus arbitration means for determining the presence or absence of the right to use the bus from the states of the data identification signal and node priority signal in the data frame signal sent on the bus, and controlling the transmission means in accordance with the determination result; and a data discarding device that compares the data identification signal in the data frame signal on the bus with the data identification signal registered in advance in the node concerned, and controls the discarding of the received data frame signal in accordance with the comparison result. A control means is provided on the receiving side.

[Effect]

According to this configuration, the presence or absence of the right to use the bus is determined using two signals, the data identification signal and the node priority signal.

〔Example〕

The present invention will be described below with reference to embodiments shown in the accompanying drawings.

FIG. 1 shows the overall configuration of this embodiment system, in which a plurality of controllers (nodes) 1 to M are connected to a 1-bit bus BS.
It is connected to the. These plurality of nodes 1 to M all have the same configuration and include a communication section 10 and a memory 20 inside.

FIG. 2 shows a data frame signal used in this embodiment system. In contrast to the conventional data frame signal shown in FIG. 5, a node identification code (node ID code)
I am trying to add an NID. That is, in FIG. 2, DID, data ID code NID/note ID code DL, data length code DT; data body ERR, error check code such as CRC.

The node ID code NID serves both to identify each of the nodes 1 to M and to identify the priority order of each node, and different code contents are set for each node.

Like the data ID code DID, this code NID also has a priority order that increases as the number decreases, with 000...0 having the highest priority.

As mentioned above, the data ID code DID is used to identify the message content (data name), and the same code should be set for common data that is commonly used across multiple nodes. There is. Regarding these common data, the priority order is distinguished using the node ID code NID, so that bus arbitration can be performed when data is simultaneously transmitted.

That is, in this device, the node ID code NID
Manage data transmission using two codes:

Note that, for example, when the data frame signal indicates "on" of a light, the data ID code DID indicates that it is a command regarding turning on/off the light,
The data body DT indicates "on".

The bus BS shown in FIG. 1 is subjected to pull-down processing, and the state of the bus is determined according to the following two rules.

・Rule 1. If all nodes transmit "1", the state of bus BS becomes "1".

-Rule 2: If there is even one node transmitting "0", the state of bus BS becomes "0".

FIG. 3 shows the internal configuration of each node 1 to M.
It includes a communication section 10, a memory 20, an information processing section 30, a control input/output interface 40, and a communication control section 50.

The control input/output interface 40 is connected to actuators that drive a load according to control data from the node 1 and sensors that input detection data etc. to the node 1. Perform alignment.

The information processing unit 30 converts the data DT in the received data frame signal into a signal that can drive the actuator connected to the node, and converts the signals from the sensors connected to the node into data of the data frame signal. D
Performs processing such as conversion to the T format and error checking processing.

In the data buffer 21 of the memory 20, a data ID code DID corresponding to data used in the node is registered in advance. Moreover, this data buffer 21 has
It also has a work area for temporarily storing transmitted and received data.

The node ID setting memory 22 has a node ID code NID corresponding to the node set in advance, and its output is connected to the ID adding circuit 12.

The communication section 10 includes a data buffer control section 1, an ID addition circuit 12, a bus arbitration circuit 13, a bus input/output interface 14, and a data reception circuit 15.

The data buffer control unit 11 reads and writes data from and to the data buffer 21, and in the reception process, compares the data ID code DID of the received data with the data ID code DID registered in the data buffer 21, and only when they match, transfers the received data to the data buffer 21. Write to buffer 21.

The ID addition circuit 12 receives the data ID code DID and data length code D received through the data transfer control unit].
L, memory 2 for setting node ID for data body DT
Add the registered node ID code NID to 2.

Data receiving circuit 15 is bus input/output interface 1
4, and manually inputs the received data to the data buffer control section 11.

The bus arbitration circuit 13 arbitrates bus usage by monitoring the bus BS and comparing the data ID code DID and node ID code NID in the data frame signal bit by bit when transmitting data. In this case, if a certain node detects that the rlJ is a bus or "0" even though it has sent an rlJ, it will send it (because this means that a message with a higher priority than the message it is sending is being sent). is stopped, and reception processing is started.

The communication control unit 50 causes each component of the communication unit 10 to perform a transmission operation in response to a data transmission request from the information processing unit 30, and also performs an operation of transmitting a data reception request from the data buffer control unit 11 to the information processing unit 30. Let's do it.

Next, to explain the transmission operation, the information processing unit 30 calculates the data ID code DI and data length code in the data frame signal shown in FIG. 2 from the sensor data received via the control input/output interface 40. DL and data body DT are formed, a data transmission request is issued to the communication control unit 50 by designating the data ID code DID, and these are written into the data buffer 21.

In response to this, the communication control unit 50 causes each component of the communication unit 1° to perform a transmission operation, and also specifies the data ID code DID to the data buffer control unit 11. The data buffer control unit 11 reads data (DID, DL, and DT) corresponding to the designated data ID code DID from the data buffer 21 and inputs them to the ID adding circuit 12. The ID adding circuit 12 adds the setting contents of the node ID setting memory 22, that is, the node ID code NID, to the input data, and further adds an error check code ERR to form the data frame signal shown in FIG. , which is input to the bus arbitration circuit 13.

The bus arbitration circuit 13 performs bus arbitration according to the procedure shown in FIG. In other words, first check the status of the bus BS,
When the bus BS is empty, a transmission operation is started (steps 100 to 12o). When the transmission operation is started, it is determined whether or not there is a data collision (step...130).
If there is no collision, the transmission operation continues from now on until the transmission is completed (steps 170, ]80). If there is a data collision, first monitor the bus BS and compare the data ID code DID at the head of the data frame signal bit by bit to check whether there is data with a higher priority than the own node ( Step...140), if there is, interrupt the transmission operation (Step...160)
.

However, if it is determined in step 140 that there is no data with a higher priority than the own node, then the node ID code NID in the data frame signal is compared bit by bit to determine the node ID code NID with a higher priority than the own node.
(Step 15)
0), if there is, the transmission operation is interrupted; otherwise, the transmission operation is continued.

That is, as mentioned above, in the Hass BS, rOJ is dominant, and if "0" and "1" collide on the bus BS, the signal on the Hass BS becomes "0", so the data ID code DID on the bus BS By monitoring the node ID code NID, you can know whether there is a message with a higher priority than the one you sent, and as a result, among the messages sent, only the one with the highest priority or the last remain until

For example, in FIG. 1, assume that node 1 and node 2 simultaneously send out common data between nodes 1 and 2. It is assumed that a node with a smaller node number has a higher priority. The bus arbitration circuit 13 of node 1 and node 2 first checks the data ID code DID on the bus BS, or in this case, since the data is common data, the priority order is the same, and at this point, node 1 and node 2 Both have the right to use Hass BS. Next, in each node 1.2, the node ID code NID on the bus BS is checked.In this case, since the node 1 side with the smaller number has a higher priority, the node 1 side is given the right to use the bus BS. or given.

In the above transmission operation, if the transmission is interrupted or terminated due to a data collision, the node immediately goes to the receiving side and waits to receive data (step...190.2).
00).

Next, the reception operation will be explained.

Each node prepares for data reception and is ready for data reception when not in a transmission operation.

When data is sent in this state, the received data is sent to the data receiving circuit 15 via the Hass BS input/output interface 14, where an error check is performed and the data ID code DID is detected from the data frame signal. The data body DT is taken out and input to the data buffer control section 11. The data buffer control unit 11 checks whether the same data ID code DID as the manually entered data ID code DID is registered in the data buffer 21. If the data ID code DID entered manually is the same as the data ID code DID, the input data ID code DID and the data body DT are transferred to the data buffer 21. While storing it in the buffer 21,
A data reception request specifying the data ID code DID is input to the communication control unit 50. The same data I according to the above comparison
If the D-code DID is not present, the received data frame signal is discarded.

The communication control unit 50 inputs the input data reception request and data ID code DID to the information processing unit 30. Thereby, the information processing section 30 reads the corresponding data body DT from the data buffer 21, and performs predetermined information processing based on this. For example, data is output to the actuators of the node via the control input/output interface 40 to drive the actuators.

According to this embodiment, the node ID code NID indicating the priority of each node is added to the data frame signal, and the Hass BS arbitration is performed using two ID codes, the node ID code NID and the data ID code DID. Since this is done by using the ID code and common data, the memory capacity for the ID code and common data can be reduced. Also, when receiving, the above two I
Since the receiving operation can be performed using only the data ID code DID among the D codes, management of the common data becomes easy even when a large amount of common data exists.

〔Effect of the invention〕

As explained above, according to the present invention, bus management is performed using two signals, the data identification signal and the node priority signal, so even if the number of nodes or common data increases, common data, etc. In addition to reducing the memory capacity required for data processing, the management of common data becomes easier.

15... Data receiving circuit, 20... Memory, 21... Data buffer, 22... Memory for node ID setting, 30... Information processing section, 40... Control input/output interface, 50 ...Communication control section

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing data frame signals used in the embodiment, Fig. 3 is a block diagram showing the internal configuration of each node, and Fig. 4 is a bus arbitration diagram. FIG. 5 is a diagram showing a conventional data frame signal, and FIG. 6 is an external configuration diagram of an in-vehicle multiplex communication system. 1 to M...Node (controller), 10...Communication unit,]
1...Data buffer control unit, 12...I'D addition circuit, 13...Has arbitration circuit, ]4 Hass input/output interface Figure 1

Claims (1)

[Scope of Claim] A multiplex communication device in which a plurality of nodes are connected to a bus in which one of binary signal levels is given priority, and multiplex communication is performed between the plurality of nodes, wherein each of the nodes transmits data. transmitting means for transmitting a data frame signal including a data identification signal indicating a name and the priority of the data, a node priority signal indicating the priority of the node, and data; and a data frame signal sent onto the bus. The transmitting side includes bus arbitration means for determining the presence or absence of the right to use the bus from the states of the data identification signal and node priority signal in the bus, and controlling the transmitting means in accordance with the result of this determination; The receiving side is provided with a data discard control means for comparing the data identification signal in the data frame signal with a data identification signal registered in advance in the node, and controlling the discarding of the received data frame signal in accordance with the comparison result. A multiplex communication device characterized by: