JPH02268531A - Communication system - Google Patents

Abstract

PURPOSE:To detect abnormality in data transmission mutually among plural processors by providing a code transmission means to transmit a code area after updating with prescribed sequence at every operation of a program, and an abnormality detecting means to detect the abnormality in data communication by judging the above update at each of plural processors. CONSTITUTION:The processor 1 at a transmission side transmits the code area of a communication data unit by its code transmission means after updating with prescribed sequence at every operation of the program. Meanwhile, the processor 2 at a reception side receive the communication data unit from the transmission side by its abnormality detecting means, and also, judges whether or not the value of the code area of the communication data unit is updated according to the sequence of the code transmission means at the transmission side. When noncoincidence is obtained, it is judged that the abnormality occurs in the data communication. In such a way, it is possible to monitor the abnormality mutually among the plural processors 1 and 2.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a communication method for performing data communication between a plurality of processors, and in particular, to an improved detection means for detecting an abnormality in data communication. Regarding communication methods.

(Prior Art) In recent years, in large industrial plants such as nuclear power plants, it has been considered to apply processors to systems extremely important for safety, such as safety protection systems.

In this case, it is desirable to detect processor failure early so that processor failure does not affect system safety.

Furthermore, it is necessary to provide redundancy to the processors so that even if one processor fails, the failure does not affect the entire system.

In this case, it is usual to provide communication means for exchanging data between a plurality of processors configured in a redundant system.

For example, it is conceivable to apply data from a system such as a security system to a plurality of processors, compare the outputs of these processors, and output data only when the outputs match.

Therefore, such communication means between a plurality of processors is extremely important, and it is necessary to promptly detect any abnormality that occurs in the communication means.

Furthermore, if the processors that make up the redundant system can monitor the operations of other processors through such data communication, mutual monitoring between multiple processors can be performed, and abnormalities can be detected more quickly. This makes it possible to detect the problem quickly at each stage, increasing the safety of the system.

By the way, as communication methods for exchanging data between a plurality of computer systems such as processors, there are the following conventional methods.

(1) Serial communication method This is basically a method in which data transmission is performed by transmitting bits consisting of rlJ rOJ on one transmission line in time series.

(2> Parallel communication method This is a method of transmitting bit signals of multiple "1" and "0" signals on multiple transmission lines (8 or 16 signal/q lines are often used as data transmission lines). This is a method that transmits data by simultaneously transmitting data.

These are also R8232C and R due to differences in transmission methods.
There are many types of communication methods, such as 8422 (serial communication method) and GPIB (parallel transmission method), and the following methods are known as data transmission error detection methods in this communication.

(1) Parity check (2) CRC (3) Check sum All of these are per transmission unit of transmitted data (usually 8 or 16 bits, but in special cases it may be longer or shorter). Errors are detected by focusing on the number of bits that are 1 in the transmission data, or the total number of bits that are 1 in the transmitted data.

In addition, we focused on the time required for transmission and the timing of data transmission and reception between the receiving processor and the transmitting processor. There is a timeout monitoring method, etc., which measures the time until the end of data transmission and detects an error when this measured time exceeds a certain fixed period of time.

(Problem to be Solved by the Invention) However, all of these error detection methods merely detect bit gaps (missing) in transmitted data or the position of transmission timing, but cannot detect the cause thereof. do not have.

For example, if a parity error is detected, it means that the data went from 1 to 0 or from O to 1 during data transmission, which was caused by noise during data transmission. It is not possible to identify whether this is caused by a difference in the threshold value for determining rlJ rOJ between the sending processor and the receiving processor.

In addition, if a timeout error is detected, this means that data communication was not performed within the specified time, but if only from a timeout error, the software of the sending processor that issues the transmission command is specified. It is not possible to determine whether the problem is caused by the inability to drive on the street or, for example, by a transmission line being cut.

Furthermore, it is difficult to discern whether communication cannot be performed because the transmitting processor has stopped, or whether the communication failure is due to some other cause.

The present invention has been made in consideration of the above circumstances, and its purpose is to provide a communication system that allows a plurality of processors connected via a communication line to mutually detect abnormalities in the other processor.

[Structure of the invention]

(Means for Solving the Problems) The present invention has been made to solve the above problems, and is configured as follows.

That is, the present invention provides a code transmission method in which a code area added to a transmission data unit to be transmitted is updated in a predetermined sequence for each program operation in a communication system in which a plurality of processors are connected through a communication line so as to freely transmit data. means, and abnormality detection means for receiving the transmission data unit, determining whether the received value of the code area is updated according to the sequence of the code transmission means, and detecting an abnormality in data communication,
It is characterized in that each of the processors is provided with one of the processors.

(Operation) Each time the processor on the transmitting side operates a program using its code transmitting means, it updates the code area of the communication data unit in a predetermined sequence and transmits the updated code area.

On the other hand, the processor on the receiving side receives the communication data unit from the transmitting side by its abnormality detection means, and checks whether the value of the code area of the communication data unit is updated according to the sequence of the code transmitting means on the transmitting side. If they do not match, it is determined that an abnormality has occurred in this data communication.

Since these code transmitting means and abnormality detection means are provided in each of the plurality of processors, abnormality monitoring can be mutually performed among the plurality of processors.

(Example) An example of the present invention will be described below based on FIGS. 1 and 2.

Figure 2 shows the communication method according to the present invention in 8 bits (1 byte).
FIG. 2 is a configuration diagram of an embodiment when applied to unit serial communication; in order to simplify the explanation, only a transmitting processor 1 and a receiving processor 2 are shown, and other processors are omitted.

The transmitting processor 1 is connected to the receiving processor 2 via a communication line 3 for data transmission, so that data can be transmitted bidirectionally between the transmitting and receiving processors 1.2.

The transmitting and receiving processors 1.2 each have code transmitting means and anomaly detecting means.

The code transmitting means updates and transmits the code area of the communication data unit 4 shown in FIG. 1 in a predetermined sequence for each program operation.

The communication data unit 4 is configured as shown in FIG.
For example, one transmission unit consists of 1 byte (8 bits) of data with 5 start bits, 6 stop bits, and 7 parity bits for detecting transmission errors. There is.

In FIG. 1, n is the number of data units to be transmitted, and checksum 8 is the number of units of data to be transmitted.
, and these are set by the code sending means.

That is, the code transmitting means is configured so that the transmitting processor 1 issues a transmitting command at least once every time the program runs once, even if there is no data to actually transmit.

Normally, when a processor is applied to a plant or the like, the program is repeatedly run on a regular basis.

The code transmitting means sets a value in the counter of the transmitting processor 1 each time it issues a transmitting command, but this value is set in a predetermined sequence so that it increases or decreases by one each time it issues a transmitting command. is programmed.

Therefore, as long as the transmitter Brossena 1 is operating, the value of the counter continues to increase or decrease by one.

On the other hand, the abnormality detection means receives the transmission data unit transmitted from the transmission side processor 1, and determines whether the value of the code area of the received data unit is updated according to the sequence of the code transmission means, and determines whether or not the value of the code area of the received data unit is updated according to the sequence of the code transmission means. Configured to detect anomalies.

That is, the abnormality detection means temporarily stores the value of the counter set by the code transmission means every time a transmission data unit is input.

Then, when the next data is input, the abnormality detection means compares the counter value input this time with the counter value input last time.

If the counter value increases or decreases by one compared to the previous value, the data transmission is normal because the predetermined sequence of the code transmitting means is followed; otherwise, it is determined to be abnormal.

Therefore, according to this embodiment, an abnormality in the operation of the transmitting processor 1 can be detected by monitoring the value of the counter of the abnormality detecting means of the receiving processor 2.

In this 11th example, the sending processor 1 is provided with the code transmitting means and the abnormality detecting means, while the receiving processor 2 is provided with the abnormality detecting means and the code transmitting means. Even when data is transmitted in the reverse direction from the processor 2 to the transmitting processor 1, an abnormality in the receiving processor 2 can be detected by the abnormality detection means of the transmitting processor 1.

Although the above embodiment describes the case where the present invention is applied to a communication method of 8-bit serial transmission, the present invention is not limited to this, and can also be applied to serial transmission of other bit numbers or parallel transmission, for example. can do.

Furthermore, even in a communication system in which the transmitting and receiving processors 1 and 2 are connected via a shared memory, 61 may be configured to allocate a specific address of the shared memory to the counter.

Furthermore, as a method of updating the code area, that is, a method of setting the value of the counter of the code transmitting means, the method of updating the code area is as follows.
In the example, the method of increasing or decreasing one by one was explained, but the present invention is not limited to this. For example, the present invention may be configured to issue a plurality of transmission commands during one running cycle of the program, and respond to each one. The required code may be set in a counter.

According to this method, depending on the code content, the receiving processor 2 can detect whether the transmitting processor 1 is always operating periodically, and also check whether the transmitting processor 1 is operating in a predetermined sequence or if When the operation of the side processor 1 is stopped, it is possible to detect at what stage the operation has stopped, which has an extremely large practical effect.

〔Effect of the invention〕

As explained above, the present invention includes a code transmitting means for updating and transmitting a code area added to a transmission data unit to be transmitted in a predetermined sequence every time a program operates, and receiving the transmission data unit t. abnormality detection means for determining whether the received value of the code area has been updated in accordance with the sequence of the code transmission means and detecting an abnormality in data communication; Since each processor is provided with one, abnormalities in data transmission can be detected between a plurality of processors.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a transmission data unit transmitted by an embodiment of the present invention shown in FIG. 2, and FIG. 2 is a configuration diagram showing the configuration of a communication system to which the communication system according to the present invention is applied. . DESCRIPTION OF SYMBOLS 1... Transmission side processor, 2... Receiving side processor, 3... Communication line, 4... Communication data unit. Diagram

Claims (1)

[Claims] In a communication method in which a plurality of processors are connected through a communication line so that data can be freely transmitted, code transmitting means updates and transmits a code area added to a transmission data unit to be transmitted in a predetermined sequence every time a program operates;
an abnormality detection means for receiving the transmission data unit and determining whether or not the value of the received code area has been updated in accordance with the sequence of the code transmission means, and detecting an abnormality in data communication; A communication method characterized by being provided in each processor.