JPH03171948A - Data communication method in terminal equipment for multiplex transmission - Google Patents

Abstract

PURPOSE:To execute an economical data transmission of high reliability by performing a simple and special data processing to data for a CPU and a communication control circuit. CONSTITUTION:For instance, a communication control circuit 3 repeats data and transmits it to a CPU 2, and the CPU 2 receives it. When the data is correct data sent by a repeated state determined in advance, that is, when the repeated data all conform, the CPU 2 which receives the data operates, based thereon and executes the prescribed control. However, when an error is generated in the repeated state of the data, it is decided that the data is different and it is not used. In such a way, even if an error is generated on a wiring between the CPU 2 and the communication control circuit 3, a malfunction caused thereby and others can be avoided, and reliability of the data transmission time is enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a data communication power method in a multiplex transmission terminal device. “Conventional technology” CSMA/CD (Carrier Se
nse MultipleAccess / Coll
Detection) As one of the transmission methods, the one described below has already been proposed. This system includes a plurality of multiplex nodes interconnected through a common multiplex transmission path, and transmits data frame by frame from one of the multiplex nodes to the multiplex transmission path, and transmits data to the other multiplex nodes (terminal equipment). When the receiving multiplex node (terminal device) successfully receives the transmitted data, the receiving multiplex node (terminal device) returns a reception confirmation signal to the multiplex transmission path. Incidentally, the multiplex transmission system for vehicles (automobiles) using the CSMA/CD transmission system employs the structure shown schematically in Figure 2. In Fig. 2, the front multiplex node F, which is the terminal device 1,
N, combination switch CS, meter MT, rear multiplex node RN, etc. are all equipped with a CPU 2 and a communication control circuit 3, and these terminal devices 1 are connected to a common multiplex transmission path via a path interface circuit 4. (Multiple bus) 5. Of each terminal device 2tl (=multiple node), a front turn light signal lamp 6, a front turn left signal lamp 7, a front small lamp 8, and a horn 9 are connected to the front multiple node FN, and the combination switch CS is turn light switch 1
0, turn left switch l1, small lamp switch 12, horn switch 13, headlamp high beam switch l4 are set to 1. The meter MT has a turn light indicator 15 and a Yuichi left indicator 1.
6. A headlamp high beam indicator 17 is connected, and a rear turn light signal lamp 18.6 is connected to the rear multiple door RN. The rear turn left signal lamp 19 and tail lamp 20 (lit when the small lamp switch 7 is turned on) are connected. In the multiplex transmission system for automobiles, a frame for transmitting automobile driving information has a structure shown in FIG. 3, as an example. Frame F shown in FIG. 3 includes a transmission start code SON for recognizing the start of frame transmission, and a frame identification code ID for identifying what kind of data is assigned to each bit in the data area. and data D1 to D
N and 1 An error check code CRC to check whether there are any errors in the contents of the received frame, a data end code EOD to recognize the end of data on the receiving side, and a bit area in advance for each multiplex node. Each multiplex node has a reception confirmation area ACK-F for confirming normal reception through each bit of the area, and a transmission end code EOM for recognizing the end of frame transmission. ．． In the multiplex transmission system shown in Figure 2, data is transmitted frame by frame from one of the multiplex nodes (FN, CS. MT. RN) to the multiplex transmission path 5 using frame F in Figure 3, and data is transmitted frame by frame from one of the multiplex nodes (FN, CS. MT. RN) to the multiplex transmission path 5. When the receiving multiplex node normally receives the transmitted data and returns a reception confirmation signal to the multiplex transmission path 5, the following happens. When a frame F is transmitted from one of the multiplex nodes, the other multiplex nodes first receive the transmission start code SON to recognize the start of frame transmission, and then receive the frame identification code I[l. identifies what kind of data is allocated to each bit of the data area, and then receives 1-N pieces of data D1 to DN. Following this, an error check code CRC is sent from the transmitting multiplex node, and each receiving multiplex node uses the error check code CRC to check whether there are any errors in the received frame. , each receiving multiplex node sends a reception confirmation signal (AGK signal) to the multiplex transmission path 5. The transmitting multiplex node receives the 80K signal in the reception confirmation area A.
By receiving the data at CK-F, the receiving side recognizes that the data has been received normally. Thereafter, each receiving multiplex node recognizes the end of data by receiving the data end code EOD, and recognizes the end of frame transmission by receiving the transmission end code EOM. In the above, when the receiving multiplex node does not return an ACK signal, the transmitting multiplex node retransmits the frame a predetermined number of times, and if there is still no response, the AC
If the receiving multiplex node that does not return the K signal has left the network, it is determined that there is another failure. ``Problem to be Solved by the Invention'' In the multiplex transmission system described above, when a strong error check code CRC is added to the frame F, it is possible to eliminate errors occurring on the multiplex transmission path 5 with an extremely high probability. Can be done. However, although the probability of an error occurring in the wiring between the CPU 2 and the communication control circuit 3 in each terminal device 1 (=multiple nodes) is low, there is a means to detect the error when it occurs. There is usually no Special means include adding an error check code to the frame and checking it by the CPU, or... It is conceivable to add a sum check, a parity check, etc. for data transfer between the CPU and the communication control circuit, but these also have problems. For example, in the former method, in order to add and check the error check code of the frame by the CPU, C
This increases the burden on the PU side, and since it takes time to complete the check, it also takes time to send back the reception confirmation signal, reducing the responsiveness of the system. The latter method increases the burden on the CPU side, and also increases the circuit size of the communication control circuit, resulting in an increase in circuit size and economic disadvantage. In view of these technical issues, the present invention provides an economical and reliable terminal device for use in this type of multiplex transmission system by applying simple and special data processing to data between the CPU and the communication control circuit. The aim is to provide a method for highly efficient data transmission. In order to achieve the intended purpose, the method of the present invention provides a method for solving the problem in a multiplex transmission system in which a plurality of terminal devices are interconnected via a common multiplex transmission path. When communicating data between the CPU and the communication control circuit. These C
The present invention is characterized in that one of the PU and the communication control circuit repeats data and transmits it to the other, and when the other receives the repeated data normally, it operates based on the data.

1. In the method of the present invention, for example, the communication control circuit repeatedly transmits data to the CPU, and the CPU receives the data.

When the CPU that receives the data is correct and has been sent in a predetermined repeating manner, that is, when all the repeated data match, it operates based on this and executes the predetermined control. When an error occurs in the repetition pattern, do not use this as an indication that the data are different. Therefore, even if an error occurs in the wiring between the CPU and the communication control circuit, malfunctions due to this,
Other problems can be avoided, increasing reliability during data transmission. ``Example'' An example of the method of the present invention will be explained with reference to the drawings. The method of the present invention is applied, for example, to data communication between the CPU 2 and the communication control circuit 3 in the multiplex transmission type terminal device 1 shown in FIG. In FIG. 2, when transmitting data from the communication control circuit 3 to the CPU 2, the communication control circuit 3 repeats the data. The data repetition pattern at this time is shown in Figure 1 (a), (b) (
c) As illustrated in (d).

In other words, in the case of (a) in the same figure, data DI and data D
In the case of (b) in the same figure, part of the data DI1 and the remaining data 012 in the data DI area are repeated. In the case of (C) in the same figure, the data D1 area is repeated. An example in which some data DI1 and some data 07+ in the data D1 area are inverted and repeated, and in the case of (d) in the same figure, two data identification codes ID are repeated each other. There is.

Examples of data repetition patterns other than those shown in the figures include an example in which three or more pieces of data are repeated in the same byte, and Figure 1 (a) (b)
) (c) There are also examples in which two or more of each repeating pattern in (d) are arbitrarily combined. These combinations are determined depending on the degree of reliability required for the data to be transmitted.

The reason for inverting and repeating the data in the above is to avoid the same error occurring at the same location in the case of parallel paths. The CPU 2 that receives data of such a repetitive pattern is equipped with a function to read a predetermined repetitive pattern. Therefore, when the repetitive pattern data sent from the communication control circuit 3 is correct, the CPU 2 executes a predetermined control based on it, but when the repetitive pattern data has an error, It does not operate based on such data.

This is the same when data is transmitted from the CPU 2 to the communication control circuit 3. Thus, CPU2 and communication control times &! Even if an error occurs in the wiring between S3 and S3, troubles caused by this can be avoided. Note that when the method of the present invention is applied to the multiplex transmission system as described in FIGS. 2 and 3, when the terminal device 1 on the receiving side receives the frame F in FIG. Frame identification code ID. All you have to do is extract the data D1 to DN, etc. and write the required repetition data three times therein. Furthermore, when transmitting data from the terminal device I, a transmission start code SOM . All you have to do is add the error check code CRC, data end code EOD, etc. and send it. ``Effects of the Invention'' As explained above, the method of the present invention enables data communication between a CPU and a communication control circuit in a predetermined terminal device. One of the communication control circuits repeats the data and transmits it to the other, and the other
When the repetitive data is received normally, the system operates based on the data, which increases the reliability of communication between the CPU and the communication control circuit.Furthermore, since the repetitive data is used, the load on the CPU is small. In addition, the communication control circuit does not need to be large-sized, and the required communication can be carried out economically.

[Brief explanation of the drawing]

Figures 1 (a), (b), (c), and (d) are explanatory diagrams showing various data repetition patterns in the method of the present invention;
The figure is an explanatory diagram schematically showing the structure of a vehicle multiplex transmission system using the CSMA/CD transmission system, and FIG. 3 is an explanatory diagram showing the frame structure in the multi-insect transmission system. ■...Terminal device 2...CPU 3...Communication control circuit 4...Path interface circuit 5...・
...Multiple transmission line 5...Multiple transmission line D1... Data Dth... Part of data 012... Part Data D2... Data 021... Some data D22... Some data ID... Frame identification code

Claims (1)

[Claims] In a multiplex transmission system in which a plurality of terminal devices are interconnected via a common multiplex transmission path, when data communication is performed between the CPU and communication control circuit in the terminal device, the CPU and communication control circuit One of them repeats the data and sends it to the other, and the other
A data communication transmission method in a multiplex transmission terminal device, characterized in that when the repeated data is normally received, the data communication is operated based on the data.