JP2590108B2 - Monitor for sequence program control system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a monitor for a sequence program control system.

(Prior Art) A sequence program control is generally known in which a program specifying an operation sequence of equipment to be controlled is formed, and each step of control is sequentially advanced according to the program. Such sequence control is used in an assembly line of machine tools, a machine tool, or the like to automatically perform a next-stage operation according to a previous-stage operation.

In this sequence control, when monitoring whether or not the control is performed normally, that is, when monitoring, a program for this monitor is incorporated in a program for controlling the operation of the equipment, and an alarm is issued when an abnormality occurs. There is an idea of doing. That is, for example, when there is a limit switch that detects the forward end and the backward end of the cylinder device, since both switches are not turned on at the same time, a circuit that outputs an abnormal signal when both are turned on is incorporated. This is a method of checking the so-called rationality. However, in this method, it is necessary to change both the program for operating the equipment and the program for monitoring each time the equipment is changed, and the total program capacity for the operation and for the monitoring increases.

On the other hand, a playback type monitor device is known. In this device, the operation patterns of the respective components of the sequence control circuit when the equipment is operated for control in advance are sequentially stored, and the operation patterns coincide with those stored in the actual operation of the equipment. Whether they are present or not is sequentially collated for each corresponding step, and when they do not match, an abnormal alarm is issued. For example, Japanese Patent Application Laid-Open No. 60-238906 discloses that in a playback-type monitor device, when the above pattern mismatches occur continuously, it is determined that an abnormality has occurred, and the operation patterns before and after the occurrence of the abnormality are stored to clarify the cause of the abnormality. The idea of facilitating is described.

(Problems to be Solved by the Invention) By the way, in the case of the playback-type monitor device, even when an abnormality (a first abnormality) occurs in one of the components of the control system, the equipment continues to operate without stopping. If so, it is not known whether it is a true abnormality or not, so it is not enough to stop the equipment. However, if there is the first abnormality, the monitor apparatus tends to point out the abnormality in each of the subsequent steps. That is, when the first abnormal element, for example, when the limit switch is kept off, it is pointed out that the step is normally on when the limit switch is off, and when the limit switch should be changed even in the step where the off is normal. By not changing the on / off state, the synchronization between the transition step of the operation pattern and the step of the storage pattern is lost, and an abnormality is pointed out.

Therefore, in such a case, when the second abnormality occurs and the facility stops afterwards due to a failure, it is not possible to monitor the time point of occurrence of the second abnormality and its contents, and it is not possible to monitor the first abnormality. In the case where the second abnormality has occurred, it is not known how the first abnormality has caused the first abnormality. Even if the part is repaired, it is easy to perform the repair in a state where the root cause of the failure is not grasped, and there is a problem that the same failure occurs again even if the equipment is restarted.

(Means for Solving the Problems) In order to solve the above problems, a solution of the present invention is a sequence program control system which sequentially advances each stage of control by a program specifying an operation order of equipment,
A change detection unit that detects a change in the operation state of each element constituting the control system; and a normal state that stores the operation pattern of each element during normal operation of the equipment as a normal pattern for each step in which the pattern changes. A pattern storage unit,
A comparison unit that compares the actual operation pattern of each element detected by the change detection unit with the storage pattern of the normal pattern storage unit, and determines whether there is an abnormality in the operation pattern of each element by comparison by the comparison unit. A diagnosis processing unit that monitors each time and indicates an abnormal element when there is an abnormality; an abnormality history storage unit that stores the presence or absence of an abnormality indication for each element diagnosed by the diagnosis processing unit; and an abnormality history storage unit. In addition to removing the abnormal element stored in the monitoring target from the monitoring target, create a new normal pattern from which the abnormal element is removed as the storage pattern, from the step next to the step where the abnormal element is pointed out, the new It is provided with a comparison execution control unit that continues monitoring by comparing the normal pattern with the operation pattern excluding the abnormal element.

(Operation) In this way, in the present invention, the operation pattern and the stored pattern are compared for each step in which the pattern changes, and if an abnormality is found by the comparison, the abnormal element is indicated by the diagnosis processing unit, and The abnormality of the element is stored in the history storage unit. Thereby, the comparison execution control unit excludes the abnormal element from the monitoring target, creates a new normal pattern from which the abnormal element is removed, and compares the new normal pattern with the operation pattern from which the abnormal element is removed. Monitoring, the second and subsequent abnormal elements can be specified.

Therefore, according to the present invention, according to the present invention, when there is an abnormal element based on a comparison between the normal pattern and the operation pattern, an indication of an abnormality is stored for the element, and the element is excluded from the monitoring target thereafter. By sequentially removing abnormal elements from both the pattern and the operation pattern and monitoring them, even if the first abnormality occurs, the occurrence of the second and subsequent abnormalities can be monitored, and the reliability of the monitoring device is improved. Can be increased. Then, when abnormalities occur sequentially and the equipment stops, it becomes easy to accurately grasp all the abnormalities from the first one and to investigate the root cause of the equipment stoppage, Abnormality or failure can be prevented from recurring.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall configuration of a monitor device in a sequence program control system.

In the figure, reference numeral 1 denotes equipment whose operation is controlled, and a control system of the equipment 1 causes a plurality of detection elements (for example, limit switches) for detecting a state of the equipment 1 to process and move a work or the like. An output element (for example, a cylinder device).

Reference numeral 2 denotes an I / O state input unit for inputting a signal (IN / OUT) representing an operation state of each element, and 3 denotes a change in the I / O state by an output from the I / O state input unit 2, that is, each element. A change detection unit 4 for detecting a change in the operation pattern of the control unit 4 is a normal pattern storage unit. The normal pattern storage unit 4 causes the equipment 1 to perform a normal operation in advance, and changes the operation pattern of each element at that time for each step in which the pattern changes (I / O state of at least one element changes). Is stored as a normal pattern.

Reference numeral 5 denotes an actual operation pattern of each element obtained from the I / O state input unit 2 via the change detection unit 3 and a value of each element obtained from the normal pattern storage unit 4 via the comparison target extraction unit 6. The comparison unit compares the stored pattern with the stored pattern. The comparison result is provided to the diagnosis result unit 7. The diagnostic processing unit 7 monitors the presence or absence of an abnormality (mismatch) in the operation pattern of each element from each comparison step, and indicates an abnormal element when there is an abnormality. , The abnormality history recording unit 9 and the abnormality history storage unit 10.

The diagnosis result output unit 8 notifies the presence or absence of an abnormality of each element. The abnormality history recording unit 9 sequentially records the presence or absence of an abnormality indication for each element. The history can be output. Further, the abnormality history storage unit 10 stores the presence / absence of an abnormality indication for each element in the past one cycle. When a change about an abnormal element is extracted by the changed element extraction unit 12, the abnormality history is stored. Cancel the abnormal memory. Then, the above-described comparison and diagnosis processing is performed based on a command from the comparison execution control unit 13.

 That is, the comparison execution control unit 13 has the following functions.

When a change in the element is detected by the change detection unit 3, the comparison unit extraction unit 6 is instructed to update the monitoring step and extract the storage pattern of the next step from the normal pattern storage unit 4. Give an execution command.

The element in which the abnormality is stored in the abnormality history storage unit 10 is not monitored by the diagnosis processing unit 7 (it is determined whether or not there is a match in comparison with the storage pattern, but no abnormality is indicated). Instructions.

In the monitoring step in which the abnormal element which has been excluded from the monitoring first should be changed, when the operation pattern does not match the storage pattern of the step, this operation pattern is compared with the storage pattern of the next step, and when the pattern matches. Monitoring will continue from this step.

If the abnormal element that was previously excluded from the monitoring target changes and the storage in the abnormality history storage unit 10 is canceled, this element is included in the monitoring target, and the updating of the monitoring step, comparison, and diagnosis are stopped only at that time. I do.

In the above, whether or not the updated monitoring step should be a step in which the abnormal element previously excluded from the monitoring target should be changed depends on whether there is a match / mismatch in the diagnosis related to the abnormal element in comparison with the storage pattern. Can be detected. In other words, since the abnormal element basically does not change due to the abnormality, the fact that the diagnosis has changed from a match to a mismatch or from a mismatch to a match in the updated step means that the abnormal element changes on the memory pattern side. You can see that it is doing.

The flow of the algorithm of the control system is as shown in FIG.

First, the playback type monitor is started, and the
Whether or not there is a change in the I / O state is seen by the change detection unit 3 (S1). If there is a change, the abnormality history storage unit 10 determines whether or not the abnormal element has been pointed out in the past one cycle, and if not, the storage pattern step to be extracted by the comparison target extraction unit 6 is updated (counted). Up) (S2, S
3).

Then, it is determined whether or not the updated monitoring step is a step in which the element for which an abnormality has been pointed out in the past one cycle should be changed. If not, the normal playback type monitor monitors the operation pattern and the corresponding storage pattern. In comparison with the above, it is found that there is an abnormality. If there is an abnormality, the abnormal element and its contents are pointed out and recorded, and a plug is set up corresponding to the abnormal element and removed from the monitoring target (S4, S5).

However, if there is an element that indicates an abnormality in the past one cycle as described above, and if the element that has changed in S1 is the abnormal element, the cause of the abnormality is removed by some factor and changes to normal. As a result, the previous flag is reset, and this element is included in the monitoring target (S6). If it is determined in step S4 that the element indicated by the abnormality is a step that should be changed, the storage patterns of this step and the next step are set as comparison targets, and the one that matches is set as a monitoring step ( S7).

Next, the mode of the monitor will be described based on a specific example of the equipment.

FIG. 3 shows a specific example of the above equipment. That is, the work W is sent from the preparation station 14 to the conveyor 17 driven by the motor (M) 16 by the feeding means (SOL1) 15 and the work W sent to the processing station 18 by the conveyor 17 is processed by the processing means. (SOL2) Processed by 19 and taken out. Preparation station 14, starting point and intermediate point of conveyor 17, machining station
18 are provided with limit switches (LS1 to LS4) 21 to 24 for detecting the work W, and the processing means 19 are provided with limit switches (LS5, SL6) 2 for detecting the backward and forward ends.
5,26 are provided. In addition, a safety mat 27 is laid near the processing station 18, and a safety mat switch 28 that outputs a facility stop signal when an operator gets on the vehicle is provided.

 The control circuit of the above equipment is shown in FIG.

Pressing the automatic operation button 30 activates the relay means 31a to 31c,
As long as the automatic changeover switch 32, the safety mat switch 28, and the stop switch 33 do not operate, energization is maintained. Work W
Is in the preparation station 14 and not in the conveyor 17 and the processing station 18 and the processing means 19 is at the retracted end (LS1
And LS5 are on, and LS2 to LS4 are off), the feed means 15 is operated by the operation of the relay means 15a and 15b to transfer the workpiece W to the conveyor 1.
Send to 7.

When the work W is on it and not at the processing station 18 (LS2 or LS3 is on, LS4 is off), the motor 16 is operated by the operation of the relay means 16a and 16b to transfer the work W to the processing station. Send to 18. Processing means 19
Is not at the forward end (LS6 is off), the workpiece W is at the processing station 18 (LS4 is on), and when the retreat relay means 19c is not operated, the forward relay means 19
When the workpiece W is advanced by the operation of d and 19e to process the workpiece W and reaches the forward end (LS6 is ON), the limit switch for detecting the backward end (LS5) is OFF and the forward relay means 19f is not operated. Then, the retreat relay means 19a, 19b operate to retreat.

The patterns stored in the normal pattern storage unit 4 for the above facilities are as shown in Table 1.

When the automatic operation button 30 is pressed in a state where the work W is in the preparation station 14 but not in the conveyor 17 and the processing station 18 and the monitor is started in a state where the feeding means 15 is operated (step (1)), the work W Is sent out from the preparation station 14, and LS1 becomes (1 → 0)
Is changed, the operation pattern at that time is compared with the storage pattern of step (2). Since these two patterns match, it is determined to be “normal”, and then LS2 is set to (0
When the SOL1 changes to (1 → 0), it is compared with the storage pattern of step (3).

Hereinafter, each time the operation pattern changes as described above, it is compared with the updated storage pattern of the step to determine whether the operation pattern is normal. For example, in the state of step (4), LS3 When a failure occurs and the switch is turned on <1>, the operation pattern is as shown in (a) of Table 2.
In this case, if the abnormality is diagnosed as the change (0 → 1) of the LS3 is too fast, the abnormality is stored in the LS3, and the LS3 is excluded from the monitoring target from then on, and the monitoring step is not changed.

Since the abnormality of LS3 does not directly stop the equipment, the operation pattern is as shown in Table 2 (a).
→ (b) → (c) → ...

That is, there is a change (0 → 1) in LS1, and the operation pattern changes from (A) to (B), and this operation pattern (B)
Is compared with the updated storage pattern of the monitoring step (5). Both patterns are identical except for LS3, and no abnormality is diagnosed.

Next, the updating of the monitoring steps (5) → (6) → (7) should be performed by the change of LS3 (0 → 1 → 0), but in reality LS3 is abnormal and fixed to <1> Since the operation pattern (B) remains, the LS4 changes (0 → 1) due to the transfer of the work W from the conveyor 17 to the processing station 18, and becomes the operation pattern (C).

Due to the change in the LS4, the operation pattern (c) is compared with the updated storage pattern in the monitoring step (6), but they do not match in the LS4 and the motor M. In this case, since the monitoring step (6) is a step in which the abnormal element LS3 previously excluded from the monitoring target should be changed, the operation pattern (c) is compared with the storage pattern of the next monitoring step (7). , And LS4 and motor M do not match. Also in this case, since the monitoring step (7) is a step in which the abnormal element LS3 should change, the operation pattern (c) is compared with the storage pattern of the next monitoring step (8).
Since both match, the monitoring step corresponding to the operation pattern (c) is (8), and no abnormality diagnosis is performed.

Next, LS5 changes (1 → 0) and the operation pattern (d)
Are compared with the updated storage pattern of the monitoring step (9), and the two patterns match.

Then, the processed work W is carried out, and LS4 (1)
(0), but since the abnormal element LS3 remains <1>, the motor M simultaneously changes (0 → 1), and the operation pattern becomes (E).

Therefore, the operation pattern (e) is compared with the updated storage pattern of the monitoring step (10). However, the two do not match in the motor M, and the abnormality (second abnormality) of the motor M is stored. Is excluded from monitoring.

Next, when LS6 changes from (0 → 1 → 0), the operation pattern changes from (e) to (f) → (g), and is sequentially compared with each storage pattern of the monitoring steps (11) and (12). However, no abnormality is diagnosed because there is no discrepancy.

Then, LS5 changes next (0 → 1), but since the abnormal element LS3 remains <1>, the feeding means 15 does not operate, and the equipment stops in the state of the operation pattern (H). on the other hand,
The monitoring device operates (h) and the monitoring step (1)
By comparing with the memory pattern of the above, an abnormality of SOL1 (third abnormality) will be pointed out.

In this case, the equipment is in a situation where the conveyor 17 continues to operate and the feeding means 15 does not send the work W to the conveyor 17, but it is not clear from this situation alone why the equipment could not work on the work.

Therefore, if the monitoring device is not operating effectively, it is necessary to check substantially all the elements for abnormalities. In this embodiment, however, the first to third abnormalities are stored. Therefore, it is possible to know the reason for the above situation.

That is, since the first abnormality is that LS3 remains at <1>, the condition that LS3 is <1> and the condition that LS3 is <1> and there is no work W in the processing station 18 and LS4 is <0>
It can be understood that the second abnormality (the conveyor 17 is still operating) has occurred, and the third abnormality (the feeding means 15 is not operating) is also LS3.
Is caused by the first abnormality <1>.

Therefore, the root cause of the stop of the work on the work W by the equipment is the abnormality of the LS3, and this abnormality should be resolved.

An abnormality in the operation pattern can be pointed out by using various determination methods such as a determination based on comparison with a stored pattern and a determination based on whether or not a change in an element is performed at a scheduled time.

[Brief description of the drawings]

Drawings show an embodiment of the present invention, FIG. 1 is a block diagram showing a configuration of a monitor device, FIG. 2 is a flowchart showing a flow of monitor start control, FIG. 3 is a plan view showing an example of equipment, FIG. 4
The figure is a sequence control circuit diagram of the same equipment. 1 ... Equipment 2 ... I / O state input unit 3 ... Change detection unit 4 ... Normal pattern storage unit 5 ... Comparison unit 7
Diagnosis processing unit, 10... Abnormality history storage unit, 13... Comparison execution control unit.

Claims (1)

(57) [Claims] 1. A sequence program control system for sequentially proceeding each stage of control by a program specifying an operation sequence of equipment, a change detection unit for detecting a change in an operation state of each element constituting the control system, A normal pattern storage unit that stores an operation pattern of each of the above-described elements as a normal pattern for each step in which the pattern changes, and an actual operation pattern of each of the elements detected by the change detection unit. A comparison unit for comparing the storage pattern of the normal pattern storage unit with the storage unit; and a diagnosis for monitoring the presence / absence of an abnormality in the operation pattern of each element for each step by comparison by the comparison unit, and pointing out the abnormal element when there is an abnormality. A processing unit; an abnormality history storage unit configured to store presence / absence of an abnormality indication for each element diagnosed by the diagnosis processing unit; The abnormal element stored in the section is excluded from the monitoring target, and a new normal pattern in which the abnormal element is removed is created as the storage pattern. And a comparison execution control unit that continues monitoring by comparing the normal pattern with the operation pattern excluding the abnormal element.