JPH0276337A - Automatic diagnosis method for failures in multiplex communication - Google Patents

Abstract

PURPOSE:To complete automation and to reduce time required for an operation by allowing a microcomputer to implement the operation of a switch circuit and the discrimination of a faulty position based on a value detected by the operation. CONSTITUTION:Communication equipments 1-n are connected in series mutually by a communication trunk line 5 via an isolation unit 8 respectively. A 1st communication equipment 1 and the last communication equipment (n) are connected by a loop standby line 6. In the automatic diagnosis of a trouble, at first the communication equipment from the 1st to the last communication equipment are polled sequentially. When there is a communication equipment giving no reply to the polling, which order number of the communication equipment gives no reply is detected. When the detection is provided, the microcomputer 10 activates a switch circuit 9 to connect the communication trunk line 5 and the loop standby line 6. Then whether the communication equipment is faulty or the communication trunk line 5 tying the communication equipment and its adjacent communication equipment is faulty as to the communication equipment giving no reply is discriminated depending on the state of a communication current flowing through the loop standby line 6.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides communication between a plurality of communication devices such as sequence circuits,
In a multiplex communication system connected in series to a communication main line via an isolation unit, this technology is used to automatically detect whether or not a failure has occurred in the communication device itself or in the communication main line connecting adjacent communication devices. Concerning automatic failure diagnosis method.

(Prior art) Sequence circuits in machine tool control devices, etc., connect each sequence circuit with a communication device via an isolation unit in order to send workpieces to successive processes and process them. FIG. 3 shows an example of a conventional method of transmitting and receiving communications between communication devices. =- and n are communication devices, respectively, which transmit output signals of a sequence circuit (not shown) to other sequence circuits as necessary.

These communication devices 1.2.3. + and n are connected by a communication main line 5 via a branch switch 4, respectively.
Further, the 0 branch switch 4 connects the first communication device l and the communication device n at the final position with a loop backup line 6, and further connects adjacent communication devices with a double backup line 7. In addition to the communication trunk line 5 that constantly connects communication devices,
The loop backup line 6 and the double backup line 7 are connected to each other by switching, and the operator manually switches the connection as necessary.

In a conventional multiplex communication device having such a configuration, communication device 1
．． 2.3. +, n itself is out of order, or these communication devices 1.2.3. When there is a failure in the communication main line 5 that connects the communication devices 1.2.3. −＋
, n, or a faulty part of the communication main line 5 connecting these has been discovered. After discovering the faulty part, communication trunk 5
When the main line 5 is out of order, the loop backup line 6 or double backup line 7 is used to continue communication, and the communication main line 5 is repaired or replaced at an appropriate time.

(Problems to be Solved by the Invention) The above-mentioned conventional technology has a problem in that it takes a lot of time to operate a branch switch to discover a fault, resulting in extended system downtime. Communication again? There was also the problem that it took a lot of time to distinguish between a failure of the A-mounted body and a failure such as a disconnection of the communication main line connecting it.The present invention was made with the aim of solving these problems. It is something that

(Means for Solving the Problems) The method of the present invention connects a plurality of communication devices in series via a communication main line via an isolation unit, and
A loop backup line is provided to connect the communication device at the final position and the communication device at the final position, and when there is a failure in the communication main line or any communication device connected to it, the loop backup line is used. In multiplex communication that continues communication between other communication devices, a switch circuit is provided to connect the communication main line and the loop protection line, and from the master station to the first communication device to the final communication device. and detects whether there is a response or not, and if there is a communication device that does not respond, what number of communication device it is, and when such a detection occurs, turns on the switch circuit. The communication main line and the loop backup line are connected, and from the state of the communication current flowing through the loop backup line, it is possible to determine whether the communication device that does not respond is due to a failure of the communication device itself.
This is an automatic diagnosis method for a failure in multiplex communication, characterized by automatically determining whether the failure is in a communication main line connecting the communication device and an adjacent communication device.

(Operation) The automatic failure diagnosis method according to the present invention having such a configuration is as follows:
By having a microcomputer perform the operation of the switch circuit and the determination of the faulty part from the values detected by this operation, automation becomes complete and the time required for this operation can be significantly reduced. .

(Example) Next, a circuit prepared for carrying out the automatic failure diagnosis method according to the present invention will be described with reference to FIG. Code 1.2,3. Those indicated by ++ and n are communication devices similar to those described above. Note that the communication device here includes, for example, a PC.
This also includes link devices such as. Each communication device ii1.2.
3. =, n each have an isolation unit 8
The isolation units 8 are connected to each other in series via the communication main line 5. In addition,
A tap 5a leading to a switch box of a master station (not shown) is provided in a portion of the communication main line 5 between each communication device. The first communication fill and the communication device n at the final position are connected by a loop backup line 6, and a switch circuit 9 is connected to the loop backup line 6 and the communication main line 5. , the switch circuit 9 is controlled on/off by a microcomputer IO. There is a switch (not shown) between each communication device and the communication main line, and the microcomputer IO can automatically control the switch on and off.

The automatic failure diagnosis method according to the present invention is performed in the following steps. First, the master station polls in order from the first communication device to the communication device at the final location (step 11 in Figure 2), and then checks whether there is a response to this polling and the communication device that does not respond. If so, it is detected which communication device it is (step 12), and when this detection occurs, the microcomputer IO turns on the switch circuit 9 (step! 3) and connects the communication main line 5 and the loop. After connecting with the backup/backup line 6, from the state of the communication current flowing through this loop backup line 6,
It is determined whether the communication device receiving no response is due to a failure in the communication device itself or a failure in the communication main line 5 connecting this communication device and an adjacent communication device.

Identification of whether the failure is in the communication device itself or in the communication main line that connects the communication device is done as follows.
When the device shown in the figure operates, it first polls the first communication device l and then starts communication, but if an abnormality occurs during communication, it polls again. When there is no response from the failed communication device, the 0th switch circuit 9 is turned on (step 3), which allows the user to know the failed communication device, and the loop backup line 6 is utilized to detect the failure. Check whether there is a response from the received communication device (step 1).

When there is a response, the communication main line from the communication device to the front side (m-1 and m when the communication device that received the response is m)
It is determined that there is an abnormality in the area between In this case, basically the communication main line 5 has to be rewired, but if all else fails, communication can be resumed as is by using the loop backup line 6. If there is no response, it can be determined that the m communication device is out of order. In this case, the communication device will have to be replaced, but especially if the system is distributed, it may be possible to back it up with another communication device. 0 ROM, but this is only possible if each communication device and communication main line are isolated. Conventionally, when a failure due to a short circuit or a ground fault occurs in a communication main line, it takes a long time to restart communication, but according to the method of the present invention, this problem can be solved in a short time.

Note that although it is theoretically possible for the method of the present invention to be carried out manually by an operator without using the microcomputer, the purpose of the present invention, which is to quickly respond to failures, is achieved by doing so. It will be difficult to follow.

(Effects of the Invention) Since the present invention is a method for automatically diagnosing failures in multiplex communication configured as described above, it is possible to automatically diagnose all communication failures. In addition, complete automatic recovery is possible in the event of a breakdown in the communications main line. In this case, the time required to discover the failure and the time required to replace the communication main line with the loop protection line can be made instantaneous.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an example of a circuit to which the method of the present invention is applied, FIG. 2 is a flowchart for explaining the operation of the circuit shown in FIG. 1, and FIG.
The figure is a conventional system diagram. 1.2.3. n-Communication device 5-Communication main line 6-Loop reserve line 8-Isolation unit 9-Switch circuit 1G-Microcomputer patent Applicant Toyota Motor Corporation Fig. 1 5 Communication main line 6 Loop pre-4s woman 8 Isolation unit 9 Nui Nona circuit 10 Microcomputer Figure 2 Figure 3

Claims (1)

[Claims] (1) A plurality of communication devices are connected in series via a communication main line via an isolation unit, and a loop reserve line is provided to connect the first communication device and the communication device at the final position, and the communication main line or this In multiplex communication in which communication is continued between other communication devices using the loop protection line when there is a failure in any of the communication devices connected to the communication main line and the loop protection line, A switch circuit is provided to connect the communication devices, and the master station polls the communication devices in order from the first communication device to the communication device at the final location, and checks whether there is a response or not, and if there is a communication device that does not respond, what it is. Detecting whether it is the second communication device,
When this detection occurs, the switch circuit is turned on to connect the communication main line and the loop backup line, and from the state of the communication current flowing through the loop backup line, it is determined that the communication device that does not respond is the communication device itself. 1. A method for automatically diagnosing a failure in multiplex communication, the method comprising automatically determining whether the failure is a failure in a communication device or a failure in a communication main line connecting the communication device and an adjacent communication device.