JP2737878B2 - 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 in which a sequence program specifying an operation sequence of predetermined control equipment to be controlled is formed, and the operation of each stage of the control is sequentially advanced according to the sequence program is already known. For example, it is widely used in assembly lines of various types of machinery and machine tools for automatically and continuously performing the next operation in response to the operation in the previous operation.

By the way, in this sequence program control,
When time monitoring is performed to determine whether or not the control is performed normally, that is, when sequence monitoring is performed, another program for this monitoring is further incorporated into the sequence program for controlling the operation of the control equipment, and an alarm is generated when an abnormality occurs. Some are configured to do so. However, in such a configuration, every time the equipment is changed, it is necessary to change both the operation control program and the monitoring program of the equipment.
In addition, since two programs for the operation control and the monitor are required, there is a disadvantage that the entire program capacity is enlarged.

Therefore, recently, a playback-type sequence monitor device has been increasingly used particularly without the above-mentioned drawbacks. In this device, the operation patterns of the respective components of the sequence control circuit when the equipment is normally operated are stored in a predetermined memory in order, and the operation patterns of the equipment when it is actually operated are stored in advance. It is sequentially checked whether or not they match the reference operation pattern, and when they do not match, an alarm of abnormality is issued. In this regard, for example,
Japanese Patent Application Laid-Open No. 60-238906 discloses that in the playback type sequence monitor device, when the operation patterns do not match continuously, it is determined that an abnormality has occurred, and the operation patterns before and after the occurrence of the abnormality are stored to determine the cause of the abnormality. It describes the technical idea of facilitating the elucidation.

By the way, in the above-mentioned playback type sequence monitor, when a mismatch pattern is first obtained, in principle, all of the mismatched control elements are determined to be abnormal. Some of them (in most cases, one), and others are often determined to be abnormal in a chain due to the occurrence of a true abnormal element.

That is, in the case of the above-mentioned playback type sequence monitor device, every time there is a predetermined transition (I / O change) in the operation pattern on the equipment side, the steps on the reference storage pattern side are advanced and collated. Occurs, the event itself eventually causes a transition of the operation pattern, and the steps of the storage pattern advance, and the result of comparison of the control element that should be changed with the storage pattern of the advanced step has changed. May be determined to be abnormal. Therefore, when abnormalities are pointed out for a plurality of control elements in the above-described playback-type sequence monitor device, it is necessary to further check whether or not all of the control elements have true abnormalities. However, this is far from practical use.

Therefore, as a means to solve the above problems,
For example, an operation state change detection unit that detects a change in the operation state of each control system element that constitutes the sequence program control system, and an operation pattern of each control element during normal operation of the control equipment in which each step changes the pattern. A normal pattern storage unit that stores a normal operation pattern obtained by the operation state change detection unit and an operation pattern comparison unit that compares an actual operation pattern obtained by detection by the operation state change detection unit with a storage operation pattern stored in the normal pattern storage unit; A playback state monitor comprising a control state diagnosis processing unit, and determining whether or not the control state diagnosis processing unit matches the storage pattern of the corresponding step with the control pattern diagnosis processing unit. Receiving the mismatch determination from the match determination unit and determining the mismatched control element before the corresponding step. A comparison control unit for comparing with the one in the memory pattern of the step, and a priority for judging that a mismatched element that is changed but should not be changed in the corresponding step is preferentially determined to be abnormal by comparison with the one in the previous step. It is conceivable to configure with an abnormality determination unit.

In the playback-type sequence monitor device having such a configuration, first, when a mismatch element is pointed out from the comparison of the operation patterns, the mismatch element is changed by the comparison with the storage pattern of the previous step, although the mismatch element should be originally changed. It is checked whether the element has been mismatched because it has not been changed or the element that has been changed but should not have been changed, that is, back-checked. Since the former mismatching element that has not actually changed does not cause a transition of the operation pattern, the latter is the one that was pointed out as a chain of mismatching as a result of the actual changing mismatching element. Yes, and thus the latter discrepancy element turns out to be the true anomalous element.

Therefore, according to such a configuration, when a mismatch is pointed out by comparing the above operation patterns, it is compared with the storage pattern of the previous step, and it is changed but should not be changed. Since the elements are found, even if a plurality of inconsistent elements as described above are obtained, the true abnormal element can be relatively easily known, and the diagnostic accuracy of the sequence monitor can be improved. Will be.

(Problems to be Solved by the Invention) By the way, the operating equipment of the above-mentioned sequence program system generally has a self-holding circuit as shown in the system of FIG. 4, for example. In the case of the system shown in FIG. 4, the equipment is constructed by combining one main automatic build-up station section 100 and the automated build-up station section 100 with a sub-assembly station 300 which is manually operated via a conveyor system 200. Then, when the work in the automated build-up station section 100 is completed, the conveyor system 200 is started up, the work 500 is transferred to the sub-assembly station 300, and the sub-assembly station 300 is operated. In the above case, the start of the conveyor 200 is performed by first assembling work completion I / O in the automated build-up station section.
The logical product of two conditions of the O signal and the ON of the sub-assembly completion button (having a self-holding circuit) 400 due to the completion of the previous work in the sub-assembly station 300 is established.

However, among the logical product conditions, it is not known which of the completion of the work in the automated build-up station unit 100 and the completion of the work in the sub-assembly station 300 will end first. Therefore, two combinations (I / O patterns) always occur as follows.

[1] When the work in the automation built-up station unit 100 is completed first (* Conveyor 200 is started at the same time that sub-assembly complete button 400 is pressed.) [2] When work is completed at sub-assembly station first (* The sub-assembly complete button 400 is self-holding, and the conveyor 200 is activated by the work completion I / O output of the automated build-up station.) As described above, some control elements of the system have a self-holding circuit. And eventually I /
The transition pattern of the O output is diversified, and it becomes impossible to perform an accurate abnormality determination with the above-described sequence monitor of the break-back type (for example, in the above example, step (a), After the comparison in step (d), no matching pattern can be found).

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above problems, and each step of the control operation is performed by a sequence program specifying a control operation order of predetermined operating equipment. In a sequence program control system that sequentially proceeds according to an instruction, an operation state change detection unit that detects a change in an operation state of various control elements constituting the sequence program control system, and the various controls during normal operation of the operation equipment. A normal pattern storage unit that stores an operation pattern representing a change in the operation state of an element for each step in which the operation pattern changes, and an operation pattern of the various control elements detected by the operation state change detection unit. The normal pattern of the step stored in the normal pattern storage unit of the control elements is used for each step. And an abnormality diagnosis processing unit that monitors the presence / absence of a mismatch between the normal storage pattern and the operation pattern based on the comparison by the operation pattern comparison unit and diagnoses an abnormality in the control state. In the monitoring device of the sequencen program control system, when the operation pattern in the step does not match the normal pattern, the abnormality diagnosis processing unit sequentially compares the operation pattern at that time with a normal storage pattern that has been advanced after the next step. Then, when a matching normal storage pattern is obtained, the step is set as a monitoring step corresponding to the operation pattern, the monitoring of the operation pattern after the step is continued, while when a normal pattern is not obtained, the monitoring is performed. Check whether the operation pattern has transitioned without changing the step, and If there is no transition, it is determined that an abnormality has occurred, and diagnosis of the cause of the abnormality is performed from the control element that caused the mismatch between the operation pattern and the normal storage pattern in the comparison by the operation pattern comparison unit up to that time. .

(Operation) In the configuration of the present invention, first, the operating equipment is operated, and the actual operation pattern of each control element is sequentially monitored at predetermined steps, and if the actual operation pattern does not match the normal storage pattern. In some cases, it is checked whether or not there is a normal storage pattern that matches the step that has advanced ahead of the unmatched step. As a result, if there is a matching normal storage pattern, the step having the normal storage pattern is set as a monitoring step corresponding to the current operation pattern in the normal pattern storage unit, and the monitoring of the operation pattern after that step is continued.

In other words, in this case, in the storage in the normal pattern storage unit, the operation states of a plurality of elements are sequentially changing while repeatedly turning on and off, for example, but actually, a plurality of elements are changed simultaneously or in a different order. This means that there was a normal memory pattern that changed and matched the forward step. Therefore,
When considering the logical product (AND) condition, the operation order is simply different from that in memory, and it is an operation pattern that does not cause any problem for the equipment. Thus, the monitoring of the control state can be continued.

On the other hand, if there is no normal storage pattern corresponding to the operation pattern in the step advanced, the presence or absence of the transition of the next operation pattern is confirmed without changing the monitoring step in the normal pattern storage unit as described above. Will do. If there is such a transition, when looking at the establishment of the above logical product condition, the order of establishment is different from that just memorized, and the equipment changes its state and there is no problem at the moment, as in the previous case It is possible to see whether the corresponding monitoring step or its forward step matches the normal storage pattern. If the above transition does not occur, the cause of the abnormality can be diagnosed from the control element that caused the initial operation pattern inconsistency as an abnormality or the control element that caused the inconsistency in the subsequent forward step.

(Effects of the Invention) Therefore, according to the configuration of the present invention, when a mismatch pattern is obtained in the playback-type sequence monitor device as described above, the actual operation pattern is advanced from the mismatch step to each step. The pattern is compared with the stored pattern, and if the patterns match, the matching step is continued as the monitoring step of the normal pattern storage unit, so that the monitoring is continued. In addition to being able to prevent erroneous diagnosis due to the improper order of fulfillment of the logical product condition without lowering the accuracy, it is possible to avoid the conventional malfunction even when the transition of the mismatch pattern is diversified by the self-holding circuit. And its reliability can be improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

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

In the figure, reference numeral 1 denotes a predetermined operating equipment whose operation is to be controlled sequentially, and a control system of the equipment 1 includes a plurality of detection elements (for example, limit switches) for detecting a state of the equipment 1 and a plurality of detection elements. And an output element (for example, a cylinder device) that operates when all of the detection elements are in a specific operation state, that is, when the AND condition is satisfied.

FIG. 2 shows an example of the equipment 1 (a punch). In this example, a working head 3 provided with a drill 2 is moved up and down by a cylinder device 4 as an output element. The cylinder device 4 includes a safety mat 5
A first limit switch (LS1) 6 for training that there is no worker on the upper side, a second for detecting the positioning of the work 10 by the positioning cylinder devices 8, 9 on the table 7,
When the third limit switches (LS2) 11 and (LS3) 12 are both on, the work head 3 is lowered to perform the boring work.

In the sequence monitor shown in FIG. 1, reference numeral 15 denotes an I / O state input unit for inputting input / output signals (IN / OUT) representing the operation state of each control element, and reference numeral 16 denotes the same I / O signal.
An operation change detection unit 17 for detecting a change in each I / O state based on an output from the / O state input unit 15, that is, a transition of an operation pattern of all elements, and 17 is a normal pattern storage unit. The normal pattern storage unit 17 causes the above-described equipment 1 to perform a normal operation in advance, and changes the operation pattern at that time (the I / O state of at least one element changes).
This is stored as a reference pattern for each step.

Reference numeral 18 denotes a comparison unit that compares an actual operation pattern obtained by the operation change detection unit 16 with a reference storage pattern obtained from the normal pattern storage unit 17.
The reference storage pattern to be compared is extracted by the comparison target extraction unit 20 based on a command from the comparison execution control unit, and the comparison result becomes the actual operation pattern given to the abnormal state diagnosis processing unit 21 and the above reference. The presence or absence of a mismatch with the correct storage pattern is monitored, and the diagnosis result is provided to the diagnosis result output unit 22 and the comparison execution control unit 19.

The comparison execution control unit 19 has the following functions.

(1) First, every time the change in the I / O state is detected by the operation change detection unit 16 and the above-described control step shifts, the comparison target extraction unit 20 is notified of the corresponding monitoring step in the normal pattern storage unit 17. The storage pattern is extracted, and a comparison execution command is given to the comparison unit 18.

(2) Next, when the abnormality diagnosis processing unit 21 detects a mismatch in the operation pattern, the normal pattern storage unit 17 stores the next step after the monitoring step in which the mismatch occurred in the comparison target extraction unit 20. Give a command to extract the pattern. If the pattern does not match even in the step that has been advanced, a forward command is sequentially given to a predetermined step each time the pattern does not match, and the presence or absence of pattern matching is checked in the forward state. And this progress check (below,
When a pattern match is obtained as a result of the forward check with respect to the back check), the matched step is defined as a monitoring step corresponding to the operation pattern in the normal pattern storage unit 17, and from the step (1) The monitoring of the operation pattern is continued by the function of.

Further, in the case of the present embodiment, in order to stop the forward check, the I / O of the output element is stored in the reference storage pattern given from the comparison target extraction unit 20 to the comparison unit 18.
An output change step extracting unit 23 and an operation change detecting unit 16 for extracting whether or not there is an O change (input / output deterioration), that is, whether or not it is a storage pattern of a step with an output change.
And a change content extraction unit 24 for extracting whether or not there is an output change in the operation pattern obtained in step (1).

That is, when the pattern extracted from the normal pattern storage unit 17 is a step having an output change, the change step extraction unit 23 causes the comparison execution control unit 19 to stop the forward check. Give a stop command. Thereby, the comparison execution control unit
In step 19, when the patterns do not match, the comparison target extraction unit 20 returns the step advanced earlier to the original monitoring step, synchronizes it, and performs the subsequent extraction work.

On the other hand, if there is a transition in the operation pattern after the monitoring step is returned to the original as described above, the change content extraction unit 24 extracts the I / O change content in the transition and performs the comparison execution control unit 1.
Give to 9. As a result, the comparison execution control unit 19
Is caused by the output element of the output change step in which the forward check is stopped, the comparison target extraction unit 20
, A control command is issued so as to extract the output change step as a monitoring step, and thereafter the extraction operation is performed sequentially from the output change step.

When the output change step is extracted as a monitoring step, if the operation patterns do not match, the diagnostic processing unit 21 points out the mismatch element, and if a forward check is performed, the diagnostic processing unit 21 checks the element. Diagnosis result output part 22
, And if there is a transition of the operation pattern again, the above indication is cleared (canceled).

Accordingly, the flow of the control operation of the monitor device is as shown in the flowchart of FIG. 3, for example. First, monitoring is started by a start signal, and the presence or absence of a change in the I / O state is determined in the operation change detection unit 16, and as a result, when the predetermined change is YES, the determination result of the previous mismatched I / O is cleared. By the subsequent count-up operation, the number of the monitoring step is advanced by one (count-up), and the reference storage pattern to be extracted from the normal pattern storage unit 17 is switched to that of the next start signal. (Step S ₁
~S _3). Then, by comparing the actual operation pattern with the extracted storage pattern, if the operation patterns match,
The S ₁ sequentially monitoring step is advanced in response to, S _2, S ₃ by the I / O state changes (transition), the pattern if a mismatch, the monitoring step change in output (output element at that time It is determined whether or not there is an I / O change (steps S ₄ and S ₅ ).

When no monitoring step of output change (NO), that each time step number is sequentially advanced to the forward check, and a stored pattern of each step and forward current of the working pattern is compared (step S ₆ , S ₇ ). As a result of the forward check, if there is a pattern match up to the monitoring step having an output change, the matching step is set as the monitoring step corresponding to the current operation pattern, and monitoring from that step is continued (S7). → Return to S1).

If there is no pattern match in the forward check, a mismatch I / O element in the monitoring step with output change is pointed out, and the monitoring step advanced in the forward check is restored, and the forward to point out the elements of disagreement I / O that caused the check (step S _8).

Next, return the step number counted up a forward check that the process proceeds to step S ₉ to the original step number. Also, point out the subsequent disagreement I / O in step S ₁₀ that caused the above-mentioned forward check as a reference.

Furthermore, there was I / O state of change in the step S ₁₁ determines whether the output of the control elements that target in the preceding step S _5, the output when the result is YES the process proceeds to step S ₁₂ while counting up the step number to step number where the changes in the case of NO count down the same step numbers proceeds towards step S _12.

Next, a specific example of the monitoring operation in the facility shown in FIG. 2 will be described.

<Example 1> When the transition of the storage pattern stored in the normal pattern storage unit 17 is as shown in Table 1 below, and the transition of the operation pattern of the experiment is as shown in Table 2.

First, step (a) coincides with monitoring step (1).
When the process proceeds to step (b), the monitoring step becomes (2).

(B) and (2) do not match. Since step (2) is a step in which there is no change in output (operation of the cylinder device), the system advances one step for a forward check, and compares (b) and (3).

(B) and (3) do not match. Since step (3) is also a step in which there is no change in output, it advances one step, and (b)
And (4) are compared.

(B) and (4) do not match. This (4) is an output change step, which points out the elements of the mismatched I / O (LS1, cylinder device), and stops the forward check because the changed I / O is not the output for which the forward check was performed. The advanced monitoring step is returned to (2). Point out the mismatched I / O elements (LS1 to LS3) that serve as references.

Next, when there is a transition to step (c) (change in I / O state), the above-mentioned point of inconsistency is cleared.

In the transition to the above (c), the changed I / O elements are the LS1 and the cylinder device, and this cylinder device is the output element of the output change step (4) where the forward check is stopped. Therefore, the monitoring step is advanced to this (4) and (c) is compared with (4).

 The above (c) and (4) coincide.

Therefore, in the actual operation pattern transition, the order in which the AND condition is satisfied is merely different from that in the memory, and there is no problem as the operation of the facility, and no misdiagnosis (alarm) that causes the stoppage occurs. .

As described above, when the I / O element that has changed in the transition to (c) is the output element of the output change step in which the forward check has been stopped, the monitoring step is forcibly adjusted to this output change step. I did it,
The respective steps of the operation pattern and the storage pattern to be compared are matched based on this output element, thereby preventing misalignment.

In the case of the transition to the above (c), the pattern can be compared from the monitoring step (2) returned to the original. In this case, since (c) and (2) do not match, (c) and (3) by forward check also do not match, and the next (c) and (4) match, the monitoring step is (4). Will be.

<Example 2> Table 3 shows the transition of the storage pattern, and Table 4 shows the transition of the actual operation pattern.

(A) is consistent with (1).

(B) does not agree with (2). (2) is an output change step. Points out mismatched I / O elements (LS2, LS3, cylinder device).

By shifting to step (c), the above point of inconsistency was cleared. (C) does not agree with (2). The element of this mismatched I / O (LS3, cylinder device) was pointed out.

By moving to step (d), the disagreement point was cleared. (D) is consistent with (2).

Therefore, in the memory pattern, the AND condition is satisfied at the same time, whereas in the actual operation pattern, the AND condition is simply satisfied sequentially, and there is no problem in the operation of the equipment, and the stoppage is caused. There is no significant error (alarm).

<Example 3> A case where the transition of the storage pattern is Table 5 and the transition of the actual operation pattern is Table 6.

(A) is consistent with (1).

(B) does not agree with (2). (2) is not an output change step, so (b) and (3) are not output change steps in the forward check, so (b) and (4) are compared in the forward check. (B) and (4) also do not agree.
Since this (4) is the output change step, the mismatch I / O
Point out (LS1, LS3, cylinder device). And
Return the monitoring step only as far as the forward check advances, and point out the reference mismatch I / O elements (LS1, LS2). Next, by moving to step (c), the above point of inconsistency was cleared.

When the above (c) and (2) are compared, they do not match. Therefore, a forward check is performed in the same manner as in the above (b). That is, (c) and (3) are compared, and since they do not match and (3) is not an output change step, (c) and (4) are compared. Since (c) and (4) are mismatched, and (4) is the output change step, the element of the mismatched I / O (LS1, cylinder device) is pointed out and the monitoring step is returned to the original (2). Reference mismatch I / O elements (LS1 to LS3)
Point out. Then, since there is no change in the state of the next I / O and the equipment is stopped, an alarm is issued.

Therefore, in the case of this example, the reference mismatch I /
Although the elements LS1 to LS3 of O are pointed out, the elements LS2 and LS3 are not included in the elements of the mismatched I / O in the output change step, so that it is understood that the LS2 and LS3 are operating. As for LS1, it is pointed out by the above-mentioned reference inconsistency, and it is also pointed out that the output change step is inconsistent, and it is also pointed out that the output change step is inconsistent. It is only necessary to check the LS1 and the positioning cylinder device 8 for its operation.

The number of steps to perform forward check is
In principle, the number of AND conditions written in the sequence program may be the number (maximum number = 1). However, as in the above-described embodiment, the check may be performed from the start step of the forward check to the step at which the output changes. In other words, this eliminates the need for an extra forward check when there is a step where some of the AND conditions are already satisfied before the forward check start step, when there is a change in output due to the satisfaction of the AND condition, and the monitor runs away. Is prevented, and it is possible to cope with a case where some of the AND conditions are satisfied and the disappearance is repeated.

In the configuration of the embodiment of the present invention, first, the operation equipment is operated to sequentially monitor the actual operation pattern of each control element, and when the pattern does not match, the memory corresponding to each step advanced before the mismatch step is stored. Check if there is a pattern. If there is a matching memory pattern,
The step in which the storage pattern is present is set as a monitoring step corresponding to the current operation pattern in the normal pattern storage unit, and the monitoring of the operation pattern is continued from that step.

In other words, in this case, in the storage in the normal pattern storage unit, the operation states of a plurality of elements are sequentially changing while repeatedly turning on and off, for example, but actually, a plurality of elements are changed simultaneously or in a different order. There is a memory pattern that changes and matches the forward step. Therefore, AND
Considering the conditions, since the order of fulfillment is simply different from the stored one and the operation pattern does not cause any problems for the equipment, the monitoring of the control state can be performed without issuing an abnormal alarm that would cause the equipment to stop operating. Can be continued.

If there is no storage pattern that matches the operation pattern in each of the steps that have been advanced, the transition of the next operation pattern is waited without changing the monitoring step in the normal pattern storage unit. With this transition,
When examining the fulfillment of the AND condition, the order of fulfillment is different from the one that was simply memorized, and the equipment changed its state and there was no problem at the moment, and the corresponding monitoring step or the forward step as in the previous case A match / mismatch with the storage pattern of the step can be seen. If the above transition does not occur, the cause of the abnormality can be diagnosed from the element that caused the initial pattern mismatch as an abnormality or the element that caused the mismatch in the subsequent forward step.

Therefore, according to the configuration of the embodiment of the present invention, in the playback type sequence monitor device as described above, when the mismatch pattern is obtained, the actual operation pattern is stored in each step advanced from the mismatch step. Compared with the pattern, if the pattern matches, the matching step is continued as the monitoring step of the normal pattern storage unit, so that the monitoring accuracy is reduced when the control proceeds due to the satisfaction of the AND condition. In addition to preventing erroneous diagnosis due to the improper order of fulfillment of the AND condition, even if the transition of mismatched patterns is diversified by the self-holding circuit, malfunction can be avoided as in the past, and its reliability Can be improved.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is a block diagram showing a configuration of a sequence program monitoring apparatus according to the embodiment, FIG. 2 is a perspective view showing an example of equipment, and FIG. FIG. 4 is a flowchart of the apparatus, and FIG. 4 is a system diagram of a conventional example. 1… Actuating equipment 4… Cylinder device (output element) 6, 11, 12… First to third limit switch (detection element) 10… Workpiece 16… Operation state change detection unit 17… Normal pattern Storage unit 18 Comparison unit 19 Comparison execution control unit 21 Abnormality diagnosis processing unit

Claims (1)

(57) [Claims] In a sequence program control system which sequentially advances each step of the control operation according to an instruction according to a sequence program designating a control operation sequence of predetermined operation equipment, operation of various control elements constituting the sequence program control system An operation state change detection unit that detects a change in state, and an operation pattern representing a change in the operation state of the various control elements during normal operation of the operation equipment are stored for each of the steps in which the operation pattern changes. The normal pattern storage unit, the operation patterns of the various control elements detected by the operation state change detection unit, and the normal patterns of the corresponding steps stored in the normal pattern storage unit of the control elements for each step. The operation pattern comparison unit to be compared and the normal memory pattern And an abnormality diagnosis processing unit that monitors the presence or absence of a mismatch between the operation pattern and an abnormality diagnosis processing unit that performs an abnormality diagnosis of a control state, wherein the abnormality diagnosis processing unit includes an operation pattern in the step. When the normal pattern does not match, the operation pattern at that time is sequentially compared with the normal storage pattern advanced after the next step, and if a matching normal storage pattern is obtained, the step corresponds to the operation pattern. While the monitoring of the operation pattern after the step is continued as a monitoring step, if a normal pattern is not obtained, the presence or absence of a transition of the operation pattern is checked without changing the monitoring step, and there is no transition of the operation pattern. In this case, it is judged as abnormal, and the operation pattern comparison unit Sequence program control system of the monitoring device, characterized in that the storage pattern is configured to perform a diagnosis of abnormality cause the control element that caused the discrepancy.