JP2001209410A - Method for specifying i/o module defect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method to automatically specify a defect of I/O module mounted on a rack without stopping a power supply to realize a short-time module replacement. SOLUTION: The method specifies a defected I/O module by repeating bus checking releasing each I/O bus from the CPU side at defect occurrence time, so as to be able to send out a signal 3 for releasing the bus from CPU to each slot, making a means 2 plysically releasing the bus of each I/O module to specify which I/O module has a defect, when the defect of bus short, etc., occurs in some I/O module, in the case of rack mounted programmable controller mounting a module on a mount base installed bus line 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for specifying a faulty I / O module in a rack-mount type programmable controller (hereinafter abbreviated as PLC) for mounting a module on a mount base.

[0002]

2. Description of the Related Art FIG. 3 is a schematic block diagram of a conventional rack-mount type programmable controller PLC in which modules are mounted on a mount base on which a bus line is installed. As shown in FIG. 3, when a failure such as a bus short circuit occurs in a certain I / O module (for example, slot 1) of each slot connected to the bus line,
In this system, each I / O is connected to a common bus line from the CPU.
O module is connected and CP
Since data communication and bus checking are performed with the U, the I / O modules (slot 2, slot 3,...
Since the I / O service cannot be performed and the bus check cannot be performed for each I / O module, it is impossible to automatically identify the failed I / O module. Therefore,
In order to identify a failed I / O module, a method has been adopted in which a worker goes to a place where equipment is installed, and separates each I / O module (slots 1 to n) to individually check.

[0003]

However, in the above conventional example, it takes time to specify the faulty I / O module, and it is necessary to turn off the power of the system.
In a situation where the system cannot be stopped, there is a problem that a failed module cannot be specified. In view of the above, the present invention enables the replacement of a failed module without powering down the system by automatically specifying the failed module by software from the CPU side.
It is an object of the present invention to provide a method of specifying a failed I / O module that can suppress a decrease in throughput (operating rate) due to a stop of a system.

[0004]

In order to achieve the above object, the present invention relates to a method for specifying a faulty I / O module in a rack mount type programmable controller in which a module is mounted on a mount base on which a bus line is installed. A certain I in the I / O module of
A means for physically releasing the bus of each I / O module in order to identify the I / O module in which the failure has occurred when a failure such as a bus short circuit occurs in the / O module; A signal is sent from the CPU to means for releasing the bus of each slot to release the bus of the I / O module, and a bus check is repeated for each I / O module to specify the faulty I / O. I have.
According to the method of specifying the failed I / O module, the CPU
Sends a bus release signal to each slot,
The I / O bus is disconnected, the bus check is sequentially performed on slots other than the disconnected slot, and the failed I / O module is automatically specified, thereby replacing the failed module without stopping the power supply of the system. Can be.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an I / O bus interface unit of a PLC according to an embodiment of the present invention. FIG. 2 is a flowchart of the operation of the PLC shown in FIG. In FIG. 1, reference numeral 1 denotes an I / O bus line (mount base) from a CPU, and 2 denotes means for physically opening a bus interface of each I / O module.
For example, the internal bus I / F is provided by a switch element such as a relay.
Is a SW circuit for disconnecting the switch. Reference numeral 3 denotes a signal from the CPU, which is an ON / OFF signal for operating the bus release means 2 of each of the slots 1 to n on the mount base. FIG. 1 shows the configuration of a general I / O bus line of a programmable controller PLC. An actual rack mount type PLC is mounted on, for example, a mount base (6 to 16 slots). Power supply module, CPU module, input / output I / O module (DC24V, AC100, 200V, relay),
It has a configuration of a motion module for controlling servos 1 to 4 axes, a communication module, a remote I / O module, and the like.

Next, the operation will be described. Now PLC
An abnormality is detected by the self-diagnosis function (a bus check, a watchdog timer, a memory check, a ladder check, a battery check, a higher-order link check, etc.) of an I / O module (for example, a slot). If a failure such as a short-circuit of the bus occurs in 1), the conventional common bus system cannot perform a normal bus check, so that the slot 1 cannot be specified as a bus short-circuit location.
Indicates the ON / OFF signal 3 of the SW circuit and the S
The faulty slot is automatically transmitted to the W circuit (bus release means) to release the bus of each slot in order and to check the existing bus. In the following, the number of slots is usually n stages, but for simplicity of description, as shown in FIG.
Description will be made as a two- or three-stage configuration.

Hereinafter, a specific procedure will be described with reference to FIG. Now, the CPU releases (OFF) the SW circuit 2 of the slot 1 by the signal 3 while the power of the system is ON (S1).
00). Subsequently, at monitoring timing based on the scan cycle, the CPU utilizes the existing bus check performed in a polling manner using an empty time slot for data communication, and performs a bus check sequentially from the other slot 2 onward. Perform (S101). It is determined from the check result whether slots 2 and below are normal (S102). If it is determined that the slot 1 is normal, the slot 1 is identified as abnormal, and the monitor displays a fault location and details of the fault such as "slot 1, bus short" on the monitor (S103). If it is determined in S102 that the check result of the slot 2 and below is abnormal, the SW circuit of the slot 2 is released (OF).
F), and the slot 1 returns the SW circuit to connection (ON) (S104). Next, the bus of slot 1 and slot 3
A check is performed (S105). It is determined whether the check result is normal (S106). If it is determined that the bus is normal, the CPU identifies and displays the failed bus as slot 2 (S107). Also, in the determination of S106, slots 1, 3
If the result of the following check is abnormal, slot 2 is reconnected and slot 3 is released (S10).
8). Subsequently, a bus check for slots 1 and 2 is performed (S109). Judge the check result (S
110). If the result of the determination is normal, the failed bus is specified to be slot 3 and that fact is displayed (S111). S
If it is determined that there is an abnormality in the determination of 110, slot 1,
The results of the check performed by releasing the slots 2 and 3 individually and sequentially are all abnormal, and it is determined that this is a failure in a plurality of slots. The processing in this case is, for example, to release the slot 1 while leaving the slot 3 open, that is, to put the slots 1 and 3 in the released state and perform the bus check of the slot 2. Performs a check process such that the failed bus is specified as slot 1 and slot 3.
Finally, with the faulty bus in the released state, the operator performs maintenance / maintenance processing such as replacement of the I / O module in the faulty slot with reference to the monitor display, and the CPU performs the check / return processing and performs monitoring. Is displayed and the process is terminated (S11).
2). In this case, if a hot-swap type (hook type) is used in combination with the mounting structure of each module, the repair time can be further reduced.

As described above, according to the present embodiment, the CP
From the U side, the faulty I / O module can be automatically and accurately identified by a simple procedure using software such as a monitoring program, and the release / return (ON / OFF) of the bus can be freely performed for each slot. As a result, a failed module can be replaced without stopping the power supply of the system. In the present embodiment, the example of the I / O module directly mounted on each slot of the mount rack has been described. However, the present invention can be further applied to a branched remote I / O module system or the like. is there. Although the check target has been described for the bus check, the present invention is naturally extended to other function checks of the self-diagnosis function as described above, which is performed via the bus line.

[0009]

As described above, according to the present invention,
The software can automatically identify the failed module from the CPU side, and there is an effect that the failed module can be replaced without turning off the system power by the mechanism for disconnecting the bus. In addition, since there is no need for manual identification by the operator, the time required to identify the failed module, the time required to turn off the power of the entire system, and the time required for module replacement can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an I / O bus interface unit of a PLC according to an embodiment of the present invention.

FIG. 2 is a flowchart of an operation of the PLC shown in FIG. 1;

FIG. 3 is a block diagram of an I / O bus interface unit of a conventional PLC.

[Explanation of symbols]

 1 I / O bus line 2 Release means 3 ON / OFF signal

Claims (1)

[Claims] 1. A method for identifying a failed I / O module in a rack-mount type programmable controller in which a module is mounted on a mount base on which a bus line is installed, wherein a faulty I / O module is selected from among a plurality of I / O modules. Means for physically releasing the bus of each I / O module in order to identify the I / O module in which the failure has occurred when a failure such as a short circuit occurs in the bus. A signal is sent to the means for releasing the bus of the I / O module to release the bus of the I / O module.
By repeating the bus check for each module,
Failure I / O characterized by specifying an I / O module
How to identify the module.