JPH05313710A - Programmable controller - Google Patents

Abstract

PURPOSE:To continue the control without the system down even in the case that a state transition corresponding to a state transition pattern at the normal time is not detected in the redundant part of a redundant state transition pattern at the time of providing the redundant state transition pattern in the input/ output. CONSTITUTION:The redundant state transition part in the normal pattern stored in a RAM 24 is designated from an operation part interface 26; and if the state transition corresponding to the normal pattern is not detected in this designated state transition part through an input/output signal monitor line 15, an artificial input/output signal to generate the state transition corresponding to the normal pattern is generated. This signal is applied to a signal switching part 12 through an input signal switching line 16, and the signal on a PLC bus 14 is switched to this signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an anomaly monitoring function for comparing an input / output state transition pattern of a normal input / output and an input / output state transition pattern detected during an actual control to monitor an anomaly. Programmable controller, especially when input / output has a redundant state transition pattern Programmable so that control can be continued even if the state transition corresponding to the normal state transition pattern is not detected in this redundant location Regarding the controller.

[0002]

2. Description of the Related Art In a system controlled by a programmable controller, there has been proposed a configuration in which an abnormality detection function is added to the programmable controller in order to detect an abnormal operation at an early stage.

Conventionally, as a programmable controller to which this abnormality detecting function is added, a normal operation state of a device controlled by the programmable controller is stored, and this normal operation state is collated with an actual operation monitor result in real time. It is known that a method of detecting an abnormal operation of a device is performed by performing the above.

Here, the operating state of the equipment controlled by the programmable controller can be regarded as an input / output state transition pattern of the programmable controller. The input / output state transition pattern of the programmable controller is (1) programmable controller The input / output (contact) on / off state, (2) the order in which the on / off state transitions, (3) the time required for the state transition (standard value + allowable value or minimum value + maximum value), etc. It is used to realize the abnormality detection function with these as criteria.

That is, it is considered that this judgment standard is, so to speak, a data of characteristic points of a timing chart showing the operation of this system.

[0006]

By the way, the number of input devices such as sensors tends to increase in this type of system with the recent advancement of systems such as small-quantity high-mix type production lines. In many cases, redundant sensors are equipped as input devices.

In a system equipped with such a redundant sensor, the abnormality is monitored by comparing the input / output state transition pattern of the input / output in a normal state with the input / output state transition pattern detected in the actual control. With the configuration, even if a failure occurs in this redundant sensor, a situation occurs in which this is detected as an abnormality and the system goes down.

For example, when a certain sensor equipped in the system as an input device is redundant and the output of this sensor does not affect the control of this system regardless of the value, the sensor is not damaged. When it occurs, the input / output state transition pattern of the programmable controller will be different from the state transition pattern at the normal time, so the conventional programmable controller with the abnormality detection function will detect this as an abnormality and Goes down and normal operation cannot be continued.

Therefore, according to the present invention, when the input / output has a redundant state transition pattern, even if the state transition corresponding to the normal state transition pattern is not detected in this redundant portion, the system is controlled without shutting down. It is an object of the present invention to provide a programmable controller capable of continuing.

[0010]

In order to achieve the above object, the present invention provides a state transition storing means for storing a normal pattern corresponding to an input / output state transition pattern during normal control, and a control object under control execution. State transition selecting means for detecting the input / output state transition pattern, and an abnormality monitoring means for comparing the normal pattern set by the state transition setting means with the state transition pattern detected by the detecting means to monitor abnormality. And a state transition point designating unit that designates a redundant state transition point of a normal pattern stored in the state transition setting unit, and a state transition point designated by the state transition point designating unit. If the state transition corresponding to the normal pattern is not detected by the state transition detection means in , And the pseudo input generating means for generating a pseudo input to form a state transition corresponding to the normal pattern in the set state transition portion by a transition portion specifying means, characterized by comprising a.

[0011]

In the present invention, the state transition point designating means designates a redundant state transition point in the normal pattern stored in the state transition setting means, and the state transition point designated by the state transition point designating means. When the state transition corresponding to the normal pattern is not detected by the state transition detection means in the above, pseudo input / output is generated which forms the state transition corresponding to the normal pattern at the state transition location set by the state transition location designating means. It originates from the means.

As a result, even if an abnormality occurs in the input / output forming the redundant state transition point, the abnormality does not bring down the system, and the control can be continued.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the programmable controller of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a system configuration of a system configured by applying one embodiment of the programmable controller of the present invention. The system of this embodiment includes a programmable logic controller 10 and the programmable logic controller 10. Connected control object 3
It consists of zero.

Programmable logic controller (P
The LC 10 is a central processing unit (CP) that controls the overall operation of the programmable logic controller 10.
U) 11, signal switching unit 12, a plurality of input / output units (I
I / O unit) 13 and a self-repairing function unit 20. The CPU 11 and the I / O unit 13 are connected by a programmable logic controller bus (PLC bus) 14 via a signal switching unit 12, The / O unit 13 is connected to the controlled object 30.

The self-repairing function unit 20 is connected to the PLC bus 14 via the input / output signal monitor line 15 and also connected to the signal switching unit 12 via the input signal switching line 16 by a programmable logic controller bus interface ( Central processing unit (CP) that controls the overall operation of the PLC bus i / f) 21 and the self-repair function unit 20
U) 22, read-only memory (ROM) 2 in which a program for controlling the self-repair function unit 20 is stored
3. Random access memory (RAM) 24 in which normal pattern data corresponding to input / output state transition patterns during normal control is stored, random access memory (RAM) 25 forming a work area, and an interface with the user The operation unit interface (operation unit i / f) 26 is configured to include the PLC bus i / f2.
1, CPU) 22, ROM 23, RAM 24, RAM 2
5. The operation unit i / f 26 is connected to each other via the system bus 27.

Next, the operation of this embodiment will be described with reference to the flow chart shown in FIG.

First, a program of the programmable logic controller 10 for controlling the controlled object 30, that is, a PLC program is created (step 10).
1).

Here, in order to facilitate understanding of the operation of this embodiment, a simple example of the controlled object 30 will be described with reference to FIG.

The control target shown in FIG. 3 is the belt conveyor 3
1 shows a work placed thereon, and a work detection unit 32 including three sensors A, B, and C is provided to detect this work. Here, the work is two works having different lengths, that is, work W1 and work W.
2 is selectively used, and the work detection unit 32 identifies the work W1 and the work W2 by using the three sensors A, B, and C.

The method of distinguishing the work W1 and the work W2 is as follows.
(1) Work W when all sensors A, B, C are turned on
1), and (2) when the sensors A and B are on and the sensor C is off and the sensor A is off and the sensors B and C are off, the work W2 is identified. This condition is shown in a ladder circuit as shown in FIG.

That is, the ladder circuit shown in FIG. 4 detects as a work W1 when the sensors A, B, and C are all on, and as a work W2 candidate when the sensors A and B are on and the sensor C is off. Then, after the sensor A is turned off and the sensors B and C are turned off after being detected as a candidate for the work W2, the work W2 is detected.

That is, in the case of this control target,
The detection processing portion of the works W1 and W2 of the PLC program created in step 101 is described by a ladder circuit as shown in FIG.

The PLC program created in this way is a programmable logic controller (PLC) 1
0 is stored in a memory (not shown).

When the creation of the PLC program is completed, the system is actually operated according to the created PLC program (step 102). That is, the system is actually tested. At this time, the self-repair function unit 20 of the programmable logic controller 10 is
The input / output signal generated on the C bus 14 is monitored via the input / output signal monitor line 15 and the PLC bus i / f21. Here, in the case where the controlled object 30 has the configuration described in FIG. 3, and the work conveyed on the belt conveyor 31 is the work W1, the signal as shown in the time chart of FIG. 5 can be monitored. That is, as the work W1 is conveyed on the belt conveyor 31, first, the sensor A is turned on, and then the sensor A is turned on, and then the transition time t
The sensor B is turned on after a lapse of 1, and the sensor C is turned on after a lapse of the transition time t2 after the sensor B is turned on. When the sensor C is turned on, the work W1 detection signal is output.

Next, at the time of test operation of this system, P is connected via the input / output signal monitor line 15 and the PLC bus i / f21.
The transition pattern of the input / output signal monitored from the LC bus 14 is stored in the RAM 24 as a normal pattern. Here, a specific example of storing a normal pattern in the RAM 24 will be described with reference to FIG.
Will be described.

The process of storing the normal pattern in the RAM 24 is started by first setting the target input signal. In this case, the input signals of interest are the signals from the sensors A, B, and C, and the signals from the sensors A, B, and C are I / O.
It is input from the O unit 13 to the programmable logic controller (PLC) 10 and transmitted to the CPU 11 via the PLC bus 14.

Therefore, what is actually set here is C
It becomes the allocation address of the I / O unit 13 as seen from the PU 11. Next, the start point is set. in this case,
In the work detection unit 32, the work detection operation is started by the signal of the sensor A, so the start point in this case is when the sensor A is turned on, and the pattern of the input signal of interest at this time is the transition number (NO.). Set to "1". The transition pattern storage method is represented by a three-digit binary number. The most significant digit is associated with the sensor A, the second digit is associated with the sensor B, the least significant digit is associated with the sensor C, and the sensor is turned on. 1 "and OFF is represented by" 0 ".

Therefore, the transition pattern when the transition number is "1" is "100". If the transition number when the sensor B is turned on next is "2", the transition pattern at this time is "110", and the transition number when the sensor C is turned on next is "3". Then, the transition pattern at this time is "111", and when the transition number when the sensor A is turned off next is "4", the transition pattern at this time is "011", and then the sensor B is If the transition number when turned off is "5", the transition pattern at this time is "001".

As described above, in the configuration shown in FIG.
When only the work W1 is conveyed, as shown in FIG.
As the transition number changes from "1" to "5",
The transition patterns are "100", "110", "111",
It changes to "011" and "001".

Further, each time the transition pattern changes, the transition time after the transition number "1" is generated is stored, and the standard transition time tn corresponding to each transition pattern is determined after the operation ends. Here, the standard transition time tn is determined as the maximum transition time during system operation. The standard transition time tn is stored corresponding to each transition pattern. In FIG. 6, transition patterns “100”, “110”, “111”, “01”.
The standard transition times corresponding to "1" and "001" are set as "t1", "t2", "t3", "t4", and "t5", respectively.

When the storage of the normal pattern is completed in this way, next, a redundant state transition portion of the normal pattern is set as a continuable portion (step 104).

That is, in the configuration of FIG. 3, the work W
If only one is conveyed, in the work detecting section 32, the work W1 should pass if the sensors A and C are simultaneously turned on even if the sensor B is not turned on, so the sensor B is redundant. However, when the sensor B actually fails to detect the work, the work W1 is not detected, as is apparent from the ladder circuit of FIG. Therefore, the transition numbers “2”, “3”, which sensor B is on,
In "4", the sensor B is set as a continuable portion.

The setting of this continuable portion is performed by the operation unit i.
/ F26.

When the storage of the normal pattern and the setting of the continuable portion are completed in this way, the actual operation is monitored (step 105). In this production monitoring,
The normal pattern stored in step 103 and the transition pattern monitored from the PLC bus 14 via the input / output signal monitor line 15 and the PLC bus i / f21, that is, the actual operation data are constantly compared to detect an abnormality.

An abnormality occurs in this state (step 10
6) It is assumed that the sensor B has failed. FIG. 7 shows actual operation data monitored from the PLC bus 14 in this case. In this case, even if the transition time "t1" of the transition number "1" has passed, the transition to the transition number "2" when the sensor B is turned on does not occur, which is abnormal.

In this case, the actual input data is switched to the simulation data (step 107). That is, in this case, in step 104, since the sensor B is set as the continuable portion at the transition numbers "2", "3", and "4", the abnormality occurrence due to the failure of the sensor B is avoided, and the operation is performed. Control to continue.
This operation is shown in FIG. That is, if the sensor B is not turned on even after the transition time “t1” of the transition number “1” has passed, the CPU 22 generates a pseudo signal corresponding to the turn-on of the sensor B having a normal pattern, and the pseudo signal is sent to the system bus 2
7, the signal is sent to the signal switching unit 12 via the PLC bus i / f21 and the input signal switching line 16, and the signal corresponding to the sensor B on the PLC bus 14 is switched to this pseudo signal. This allows the system to continue operation despite the sensor B not producing an ON signal.

[0038]

As described above, according to the present invention,
The state transition location designating means designates a redundant state transition location of the normal pattern stored in the state transition setting means, and the state transition corresponding to the normal pattern at the state transition location set by the state transition location designating means. Is not detected by the state transition detecting means, the pseudo input / output generating means generates pseudo input / output for forming a state transition corresponding to a normal pattern at the state transition point set by the state transition point designating means. Therefore, it has the following effects.

(1) Even if a redundant sensor or the like fails, the system continues to operate without being down, so unnecessary downtime can be reduced.

(2) The behavior of the system can be easily grasped by the user by looking at the stored normal pattern.

[Brief description of drawings]

FIG. 1 is a block diagram showing a system configuration of a system configured by applying an embodiment of a programmable controller of the present invention.

FIG. 2 is a flowchart for explaining the operation of the embodiment shown in FIG.

FIG. 3 is a diagram showing a specific configuration example of a control target in the embodiment shown in FIG.

FIG. 4 is a ladder circuit describing a part of a PLC program for controlling the controlled object shown in FIG.

5 is a time chart showing input / output signals monitored by the self-repairing function unit of the embodiment shown in FIG.

FIG. 6 is a diagram for explaining a specific example of storing a normal pattern in the embodiment shown in FIG.

7 is a diagram showing an example of monitor actual operation data when an abnormality occurs in the embodiment shown in FIG.

FIG. 8 is a diagram illustrating an operation of avoiding the occurrence of an abnormality and continuing the operation when an abnormality occurs in the embodiment shown in FIG.

[Explanation of symbols]

10 programmable logic controller (PLC) 11 central processing unit (CPU) 12 signal switching unit 13 input / output unit (I / O unit) 14 programmable logic controller bus (PL
C bus) 15 input / output signal monitor line 16 input signal switching line 20 self-repair function unit 21 programmable logic controller bus interface (PLC bus i / f) 22 central processing unit (CPU) 23 read-only memory (ROM) 24 random access memory (RAM) 25 Random access memory (RAM) 26 Operation unit interface (operation unit i / f) 27 System bus 30 Control target 31 Belt conveyor 32 Work detection unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Ishiguro, 10 Odoroncho, Hanazono, Ukyo-ku, Kyoto

Claims (1)

[Claims] 1. A state transition storing means for storing a normal pattern corresponding to an input / output state transition pattern during normal control, and a state transition selecting means for detecting an input / output state transition pattern during control execution of a controlled object. A programmable controller having an abnormality monitoring unit for comparing the normal pattern set by the state transition setting unit with a state transition pattern detected by the detecting unit to monitor for an abnormality, and storing the programmable controller in the state transition setting unit. State transition part designating means for designating a redundant state transition part of the generated normal pattern, and a state transition corresponding to the normal pattern at the state transition part designated by the state transition part designating means is the state transition detecting means. If it is not detected by, the state transition location designated by the state transition location designating means There are programmable controller, characterized in that anda pseudo input generating means for generating a pseudo input to form a state transition corresponding to the normal pattern.