JPH04233852A - Communication fault discrimination system for programmable controller - Google Patents

Abstract

PURPOSE:To set number of times of communication fault discrimination to a proper value depending on the actual operating environment of the user for the programmable controller. CONSTITUTION:Number of times C of communication error discrimination is actually measured for a prescribed time T based on the time measurement in the communication fault discrimination system, which discriminates whether or not a communication error takes place consecutively for a prescribed number of times N of communication error discrimination and stops the system when a communication error takes place consecutively for a prescribed number of times N of communication error discrimination. Then an error occurrence rate is calculated based on the number of times C of communication error discrimination and a communication cycle time (t), and the number of times N of communication error discrimination is decided by the error occurrence rate.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a communication abnormality determination system for a programmable controller, and in particular to a communication abnormality determination system for a programmable controller.
The present invention relates to a communication abnormality determination system in /O systems and the like.

0002

[Prior Art] In a remote I/O system for a programmable controller, a remote I/O master station unit and a remote I/O slave unit connected to it by a transmission line such as an optical fiber cable are connected to each other. data communication is performed.

[0003] In this remote I/O system,
In general, in consideration of the occurrence of communication errors due to external noise such as ambient light, even if a communication error occurs, the system is not immediately stopped and data transmission is retried several times, but as a safety measure. , the same remote I/
When a communication error with respect to the O slave station unit continues to occur a predetermined number of times (communication abnormality determination number), it is assumed that a system abnormality has occurred and the system is automatically stopped.

0004

[Problems to be Solved by the Invention] Conventionally, in the communication abnormality judgment as described above, the number of communication abnormality judgments that cause the system to be stopped has been uniquely determined by the manufacturer based on test runs and empirical rules. There are many different environments in which programmable controllers are used, and in places with bad noise environments, the system may stop frequently and unnecessarily. On the other hand, if the number of communication abnormality judgments is set to a large value, it becomes less likely that the system will stop, but in this case, it will take time for the system to stop if a hardware abnormality occurs. A problem occurs. In other words, in the communication abnormality determination as described above, unless the number of communication abnormality determination times is appropriately set according to the actual usage environment of the programmable controller by each user, an effective communication abnormality determination that does not cause other failures can be achieved. is not performed.

The present invention has been made by focusing on the above-mentioned problems in determining communication abnormalities in conventional programmable controllers. It is an object of the present invention to provide a communication abnormality determination system that can set the value to an appropriate value.

[0006]

[Means for Solving the Problem] According to the present invention, the above object is to measure the number of communication errors in a predetermined time based on time measurement in order to determine the number of communication abnormality determinations. The actual measurement mode and the communication abnormality determination mode, which determines whether or not a communication error has occurred continuously for a predetermined communication abnormality determination number of times, and stops the system if a communication error occurs continuously for the communication abnormality determination number of times. This is achieved by a communication abnormality determination system for a programmable controller characterized by having the following.

[0007] In order to more reliably achieve the above-mentioned object, the communication error determination system for a programmable controller according to the present invention actually measures the number of communication errors in a predetermined time based on time measurement, and detects the communication error. A communication abnormality determination frequency determination mode in which the error occurrence rate is calculated from the number of times and communication cycle time, and the communication abnormality determination frequency is determined from this error occurrence rate, and a communication abnormality determination mode in which the communication error is determined in the communication abnormality determination frequency determination mode. A communication abnormality determination mode in which it is determined whether or not the communication error has occurred continuously for the number of times of determination, and the system is stopped when the communication error has continuously occurred for the number of times determined in the communication abnormality determination number determination mode. It may be characterized by having the following.

[0008]

[Operation] According to the above-described configuration, the number of communication errors is actually measured under the actual usage environment of the programmable controller by the user, thereby clarifying the noise environment under the actual usage environment of the programmable controller. Based on this, the communication abnormality determination frequency is set to an appropriate value suitable for each usage environment.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an example of a programmable controller system to which a communication abnormality determination system according to the present invention is applied. In Figure 1, 1 is the CPU unit 3
and a power supply unit 5, 7 is a remote I
/O master station units are shown, each of which is inserted into a slot of the base unit 9.

The remote I/O master unit 7 is connected to a plurality of remote I/O slave units 13 via an optical fiber cable 11, and performs data communication with each remote I/O slave unit 13. It looks like this.

A user tool 17 such as a programming console is connected to the CPU unit 3 via a connection cord 15.

As shown in FIG. 2, the CPU unit 3 includes a CPU 21, an internal memory 23, a system memory 25 that stores system programs, a user program memory 27 that stores user programs, and a time measurement system. It has a clock function section 29 that can perform functions, and an interface 31 for tools.

As shown in FIG. 3, the remote I/O master station unit 7 includes a CPU 41 and a system memory 43.
, a work memory 45, a data memory 47, a counter 49, a switching circuit 51, a PC main body connector 53, an I/0 interface 55, a serial/parallel converter 57, and an optical/electrical converter 59. , and an optical connector 61.

The system program stored in the system memory 23 includes a communication abnormality determination program. The communication abnormality determination program actually measures the number of communication errors in a predetermined time based on time measurement by the clock function section 29 of the CPU unit 3, calculates the error occurrence rate from the number of communication errors and the communication cycle time, and calculates the error occurrence rate from this number of communication errors and the communication cycle time. A communication abnormality determination frequency determining mode that determines the communication abnormality determination frequency based on the error occurrence rate, and determining whether or not communication errors have occurred continuously over the communication abnormality determination frequency determined in the communication abnormality determination frequency determination mode. and a communication abnormality determination mode in which the system is stopped when communication errors occur continuously for the number of communication abnormality determinations determined in the communication abnormality determination frequency determination mode, and either of these two modes is provided. but one is C
The commands from the tool 17 connected to the PU unit 3 are selectively executed.

Next, the operation of the communication abnormality determination system according to the present invention will be explained using FIG.

First, it is determined whether or not it is in the communication abnormality determination mode (step 10), and when it is not in the communication abnormality determination mode, that is, in the communication abnormality determination number determination mode, the communication error count value C is set to 0. Reset (step 20), then time measurement starts (step 30)
. Based on this time measurement, occurrence of a communication error is monitored under actual operation of the programmable controller for a predetermined time T (step 40), and the number of communication errors C is counted (step 50).

[0018] When the predetermined time T has elapsed (step 60)
, the number N of communication abnormality determinations is calculated according to the following formula (step 70).

N=(C/T/t)K However, t is a communication cycle time and K is a coefficient.

[0020] According to the above calculation formula, the communication abnormality judgment number N
is calculated. Note that the communication abnormality determination number N is an integer.

The number N of communication abnormality determinations calculated according to the above formula is stored in the nonvolatile memory within the CPU unit 3. As a result, the number N of communication abnormality determinations is set (step 80). The nonvolatile memory within the CPU unit 3 that stores the communication abnormality determination number N may be part of the system memory 25.

[0022] When the communication abnormality determination mode is selected,
The occurrence of a communication error is monitored for each communication cycle (step 90), and if a communication error occurs, the communication error count value C is incremented by one (step 100).
), if no communication error occurs, the communication error count value C is reset to 0 (step 110). In this case, the communication error count value C
is incremented for communication to the same remote I/O slave unit 13, and if the remote I/O slave unit 13 to which communication is made changes, the communication error count value C is reset to 0. good.

[0023] Then, the number N of communication abnormality determinations stored in the non-volatile memory in the CPU unit 3 is fetched, and it is determined whether or not the communication error count value C has reached the number N of communication abnormality determinations (step 120), when C≧N, that is, when communication errors occur continuously for the communication abnormality judgment number N in communication with the same remote I/O slave station unit 13, the system is stopped. (Step 130).

Step 70 in the flow as described above,
The process 80 may be performed manually by the user. In this case, the communication abnormality determination frequency determination mode as described above may be referred to as the communication error frequency actual measurement mode, and the communication abnormality determination program is simplified. .

[0025]

As can be understood from the above explanation, according to the communication abnormality determination system for a programmable controller according to the present invention, the number of communication errors is actually measured under the actual usage environment of the programmable controller by the user.
As a result, the noise environment in the actual usage environment of the programmable controller is clarified, and the communication abnormality determination frequency is set based on this, so the communication abnormality determination frequency is set to an appropriate value suitable for each usage environment. A valid communication abnormality determination is now performed without causing any other failures, and the system is stopped unnecessarily frequently or takes a long time to stop when a hardware abnormality occurs. No such problems will occur.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a programmable controller system to which a communication abnormality determination system according to the present invention is applied.

[Fig. 2] C used in a programmable controller system to which the communication abnormality determination system according to the present invention is applied.
FIG. 2 is a configuration diagram showing an example of a PU unit.

FIG. 3 is a configuration diagram showing an example of a remote I/O master station unit used in a programmable controller system to which a communication abnormality determination system according to the present invention is applied.

FIG. 4 is a flowchart showing the operation of the communication abnormality determination system according to the present invention.

[Explanation of symbols]

1　PC body 3 CPU unit 5 Power supply unit 7 Remote I/O master station unit 9 Base unit 11 Optical fiber cable 13 Remote I/O slave unit

Claims (2)

[Claims] Claims: 1. A communication error frequency actual measurement mode in which the number of communication errors is actually measured in a predetermined time based on time measurement in order to determine the number of communication abnormality determinations; A communication abnormality determination mode for a programmable controller characterized by having a communication abnormality determination mode that determines whether or not the communication error has occurred continuously and stops the system when the communication error occurs continuously for the number of communication abnormality determination times. Judgment system. Claim 2: The number of communication errors in a predetermined time is actually measured based on time measurement, the error occurrence rate is calculated from this number of communication errors and the communication cycle time, and the number of communication abnormality judgments is determined from this error occurrence rate. A communication abnormality determination frequency determination mode is set to determine whether or not a communication error has occurred continuously over the communication abnormality determination frequency determined in the communication abnormality determination frequency determination mode. A communication abnormality determination system for a programmable controller, comprising: a communication abnormality determination mode in which the system is stopped when the communication abnormality determination occurs continuously over the number of communication abnormality determinations determined in the determination mode.