JP2001209412A - Simulator for sequence program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simulator that runs a sequence program feasible for an effective debugging since the program can restore, immediately as requested, a status of an input and output device at the time of scan without asking a debugger to store or record revised position when the input and output device value is changed during a debugging process. SOLUTION: The simulator runs the sequence program that can run on a personal computer and enables us to stop during execution steps. The simulator has a memory region where a referenced object at the sequence program execution and data to be a setting object by the execution result are stored, and the backup region where backup contents for the memory region are stored. The simulator has a memory contents storing mean to store contents of the memory region into a backup region at the beginning of every scanning. The simulator has an initialization function that enforces to bring an execution address of the sequence program into the top address of the program while the contents of the memory region are recovered from the contents being stored in the backup region provided that a prescribed operation is accepted by the initialization function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simulation apparatus for a sequence program which can execute a sequence program on a personal computer and stop the execution of the sequence program in an intermediate step. The present invention relates to a sequence program simulation apparatus that can easily perform an operation for reproducing the execution of a sequence program.

[0002]

2. Description of the Related Art A sequence program simulation apparatus which is capable of simulating a sequence of instructions constituting a sequence program on a personal computer step by step is known.

In this type of simulation apparatus, a series of sequence programs (consisting of a sequence of instruction steps) that are originally executed collectively in units of one scan.
The program is debugged by executing the simulation step-by-step in small steps and monitoring (visually recognizing) the value of the output device (relay or the like) each time.

If the output device does not have the expected value during monitoring, the value of the input / output device (sensor or relay) related to the executed instruction step is forcibly changed, and the execution result of the instruction step is again changed. Confirm. If the value of a plurality of input / output data is changed depending on the situation, the execution result of the instruction step is confirmed again. If necessary, the program is corrected, and the operation is confirmed again using the corrected program. If it is confirmed that the operation intended by the developer is performed, the debugging of the program is completed.

[0005]

In the debugging of such a sequence program, the values of the input / output devices are appropriately changed as necessary in order to confirm the execution operation of each instruction step in the process of completing the debugging. . Therefore, in order to execute a series of instruction steps composing the sequence program one step at a time from the beginning to the end in order to confirm the final completion of debugging,
Prior to that, all the values of the input / output devices and the like changed so far must be returned to the original values at the start of scanning (corresponding to the values immediately after the input / output refresh in the actual PLC). Otherwise, even in the actual PLC,
There is no guarantee that the program will work properly.

However, in this type of conventional simulation apparatus, information on which input / output device has been changed to what value in the debugging process depends on manual recording or operator's memory. There was a problem that debugging efficiency was reduced due to forgetting to reset the value, mistake in setting the value, and requiring a lot of work to restore the value to the original value. I have.

The present invention has been made in view of such a conventional problem. An object of the present invention is to change the value of an input / output device in the course of debugging and to determine the changed portion by an operator. Is not recorded or memorized,
It is an object of the present invention to provide a sequence program simulation apparatus which can immediately restore the state of an input / output device at the start of scanning as needed, and thereby can efficiently perform this kind of debugging work.

Another object of the present invention is to change the value of an input / output device in the course of debugging without the operator having to record or store the changed portion.
It is possible to immediately restore the state of the input / output device at the time of the start of the scan in the scans designated in the past scans, thereby providing a sequence program simulation apparatus capable of more efficiently performing this kind of debug work. To provide.

Another object of the present invention is to change the value of an input / output device in the course of debugging, without the operator having to record or store the changed portion.
In the past scans, when the input / output device has changed to the specified value, the status of the input / output device at the start of the scan can be immediately restored, and this type of debugging work can be performed more efficiently. An object of the present invention is to provide a simulation device for a sequence program that can be used.

It is still another object of the present invention to execute an instruction one step at a time when a value of an input / output device is changed in a debugging process, without the operator recording or storing the changed portion. It is possible to finally restore the state of the input / output device at the start of scanning while reverting to inching, thereby providing a sequence program simulation device capable of performing this kind of debugging work more efficiently. is there.

[0011]

A sequence program simulation apparatus according to the present invention is a sequence program simulation apparatus capable of executing a sequence program on a personal computer and stopping execution at an intermediate step. A memory area in which data to be referred to and set according to the execution result are stored, a backup area for backing up the contents of the memory area, and the contents of the memory area are stored in the backup area at the start of each scan. A memory content storing means for storing, and on the condition that a predetermined operation is received, the content of the memory area is restored to the content stored in the backup area, and the execution address of the sequence program is forcibly moved to the beginning of the program. Initialization means to return to Comprising a, thereby returning to the time past scan is obtained by a reproducible execution scene program.

As a mode in which execution can be stopped at an intermediate step, various modes are known in this type of simulation apparatus. Specifically, in addition to the one-step execution mode, various automatic stop modes for automatically stopping the execution on condition that the content of the designated input / output becomes a specific value, and further, manually at any time There is a mode for stopping the program halfway. In addition, as a new mode in which execution can be stopped in such an intermediate step, a mode in which a step to be stopped is specifically specified in advance by a step number, and the execution is stopped after the arrival of the step is considered. . The present invention
Compatible with all stop modes.

According to such a configuration, when the value of the input / output device is changed in the course of debugging, the input / output device at the start of scanning can be used as needed without the operator recording or storing the changed portion. The state of the device can be immediately restored, so that this kind of debugging work can be efficiently performed.

In a preferred embodiment, there is provided a means for storing the history of the contents of the backup area for a plurality of scans, and the initialization means specifies the contents of the memory area from the history of the backup area. In addition to restoring the contents of the scan, the execution address of the sequence program is forcibly returned to the beginning of the program.

According to such a configuration, when the value of the input / output device is changed in the course of debugging, the changed portion is designated in the past scan times without the operator recording or storing the changed portion. It is possible to immediately restore the state of the input / output device at the time of the start of the scan in the scan cycle, so that this kind of debugging work can be performed more efficiently.

In a preferred embodiment, the backup area is configured to be able to store the contents of the memory area as histories for a plurality of scans, and the initialization means stores the contents of the memory area in the backup area. In addition to restoring from the history to the contents of the scan in which the designated input / output condition is satisfied, the execution address of the sequence program is forcibly returned to the beginning of the program.

According to such a configuration, when the value of the input / output device is changed in the debugging process, the input / output device can be changed in the past scan times without the operator recording or storing the changed portion. It is possible to immediately restore the state of the input / output device at the start of the scan in the scan in which the device has changed to the specified value, and thus this kind of debugging work can be performed more efficiently.

Further, the sequence program simulation apparatus according to the present invention is a sequence program simulation apparatus capable of executing a sequence program on a personal computer and suspending the execution of the sequence program in an intermediate step. A memory area in which data to be stored is stored, a backup area for backing up the content of the memory area, a memory content storage means for storing the content of the memory area in the backup area at the start of each scan, On condition that the operation is accepted, the contents of the memory area are restored to the contents saved in the backup area, and the execution address of the sequence program is forcibly returned to the beginning of the program. At the time Tsu until one step before the flop, and a re-execution means for forcibly continuously executing a sequence program, thereby executing the scene program 1
It is possible to reproduce a state equivalent to a state in which steps are reversed.

According to such a configuration, when the value of the input / output device is changed in the course of debugging, even if the operator does not record or store the changed portion, the execution of the instruction is returned to the step-by-step step by step. Then, it is possible to finally restore the state of the input / output device at the time of starting the scan, so that this kind of debugging work can be performed more efficiently.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

A first embodiment of a sequence program simulation apparatus according to the present invention is shown in FIGS. 1 is a block diagram showing a software configuration of a sequence program simulation apparatus, FIG. 2 is a functional block diagram of the sequence program simulation apparatus, FIG. 3 is a flowchart of sequence program execution processing, and FIG. 4 is a flowchart of step execution processing. is there.

As shown in FIG. 1, a simulation apparatus 1 of the present invention is a commercially available personal computer (for example, Windows 9).
5/98 / NT4.0), a debugger 101 and a simulation engine 102 are realized by software.

The simulation engine 102 includes an execution management unit 102a, a program execution unit 102b, a memory area 102c, and a backup area 102d.

The debugger 101 issues an operation instruction to the simulation engine 102 and monitors the operation of the simulation engine. The user can instruct the simulation engine 102 via the user interface of the debugger 101.

The simulation engine 102 constitutes a main part of the present invention and has a function of simulating a sequence program.

The execution management unit 102a performs a sequence program execution instruction, a memory backup process, and the like. Further, the execution management unit 102a receives an instruction from the debugger 101 and controls execution of a program.

The program execution unit 102b executes a sequence program while referring to and operating the memory area 102c. That is, the program execution unit 102b
The instruction is executed with reference to the value of the input device in the memory area 102c, and the memory area 10
Operate (rewrite) the value of the output device 2c.

The memory area 102c is a memory area referred to by the program execution unit 102b. In this memory area 102c, input / output data to be referred to when executing the sequence program and to be set according to the execution result are stored.

The backup area 102d is an area for temporarily backing up the memory area 102c. As described later, the contents of the memory area 102c are stored in the backup area 102d for each scan. Further, the contents of the backup area 102d are transferred and copied to the memory area 102c in accordance with an instruction from the debugger 101, whereby the contents at the start of scanning (contents not changed by execution of a program or the like) are stored in the memory area 102c. ) Is restored.

Next, the configuration functions and the overall operation of the simulation apparatus 1 related to the present invention will be described in more detail with reference to FIGS.

First, referring to FIG. 2, the debugger 101 has a function of receiving various operation commands or instructions from the user and a function of outputting (displaying, etc.) the operation contents to the user in a recognizable manner. It is software that effectively functions as a fulfilling man-machine interface (MMI).

The operation commands or instructions from the user include:
It includes at least (1) an instruction related to program execution, (2) an instruction to change a program during debugging or the like, and (3) an instruction to change a value of an input / output device during debugging or the like.

In particular, instructions relating to program execution include:
At least an execution (monitor mode) instruction, a stop (program mode) instruction, a pause instruction, a step execution instruction, a scan execution instruction, a continuous scan execution instruction, a scan re-execution instruction (a main part of the present invention), and the like are included. .

Here, the execution (monitor mode) instruction is an instruction to execute a program while continuously performing scanning.

The stop (program mode) instruction is an instruction to stop the execution of the program. At this time, the operation mode of the ladder execution engine automatically changes to the program mode.

The temporary stop instruction is an instruction for temporarily stopping the execution of the program. At this time, the process can be restarted in each execution mode.

The step execution instruction is an instruction for executing a process (decoding execution) for each step of a series of mnemonics constituting the program in a stepwise manner. In step execution,
The operation stops every time the program for one step is executed.

The scan execution instruction is an instruction to execute the ladder program for only one scan. When a scan execution instruction is given during the step execution, the ladder is executed to the end.

The continuous scan execution instruction is an instruction for continuously performing the scan at a constant interval.

The scan re-execution instruction is equivalent to the re-execution instruction (201) in FIG. 2. During the step execution, the contents of the input / output memory (I / O memory) are changed to the state at the start of the scan. This is an instruction to return and clear the contents of the program counter (to make it the top value). Here, as is well known to those skilled in the art, the input / output memory corresponds to the memory area 102c which is referred to or set when executing the program. The program counter functions as a pointer for managing the execution address of the program.

The execution management unit 102a receives various instructions from the debugger 101 and appropriately controls the program execution unit 102b and the memory area 102c in order to realize operations corresponding thereto. The processing related to the present invention includes a program address change processing (20) for variously changing the program execution mode.
2).

The program execution unit 102b functions as a ladder execution engine for executing a sequence program, and the program execution address of the program execution unit 102b is controlled by the execution management unit 102a.

The memory area 102c corresponds to a so-called input / output memory (I / O memory) of the PLC. In the memory area 102c, in addition to the input / output data corresponding to the input / output device, the memory area 102c is used for executing a program. Necessary timer and counter data and the like are stored. This memory area 102
Under the control of the execution management unit 102, the content of the input area is updated with the virtual input device every scan, and the content of the output area is updated with the virtual output device every scan. You. That is, the execution management unit 102a
Performs operation management based on one cycle operation including an instruction execution step, an input / output update step, and a peripheral service processing step.

As is well known to those skilled in the art, the contents of the memory area 102c are appropriately referenced (203) when executing the program. In addition, rewriting and setting (204) are appropriately performed in response to the execution result of the program.

The backup area 102d is newly provided in connection with the present invention, and includes a memory area 102d.
This is a storage area for storing the contents of c for one scan. That is, as described later, the contents of the memory area 102c (that is, the contents at the start of program execution for the latest one scan) are overwritten and saved (205) in the backup area 102d at the start of each scan. When a re-execution command (201) described later is given, the memory area 102
The content of c is restored (206).

Next, a sequence program execution operation in the simulation apparatus 1 of the first embodiment will be described with reference to FIGS. 2 and 3, focusing on step execution processing and scan re-execution processing.

In this simulation apparatus, the sequence program can be simulated on a personal computer in one-step increments. This is realized by executing the following series of processing.

As shown in the flowchart of FIG.
No scan re-execution instruction (NO in step 304)
Then, only the step execution process (step 303) is repeatedly executed. As shown in the flowchart of FIG. 4, in the step execution processing, the instruction is reset upon receiving an execution instruction for one step (step 405 YES), and is set every time the execution of the instruction for one step is completed (step 403).
By referring to the flag F1 to be executed (steps 401 and 405), it is possible to perform a step-by-step unit (step 4).
04) Instruction simulation execution operation (step 402) is performed.

In the simulation apparatus, the contents of the memory area 102c are stored in the backup area 102d at the start of each scan. this is,
This is realized by executing the following series of processes.

As shown in the flowchart of FIG.
If it is determined that the start of the scan is made by referring to the contents of the program counter (YES in step 302), the contents of the memory area 102c at that time are stored in the backup area 1
02d (step 307).

Further, on condition that a predetermined operation (scan re-execution instruction) is accepted, the memory area 102c
Is restored to the content at the start of scanning (at the start of program execution) stored in the backup area 102d, and the execution address of the sequence program can be forcibly returned to the beginning of the program. This is realized by executing the following series of processing.

As shown in the flowchart of FIG.
During the execution of the step mode, a scan re-execution instruction (FIG. 2)
Is given (step 304 YES),
The restoration process from the backup area 102d to the memory area 102c is performed (step 305), and at the same time, the value of the program counter that manages the execution address of the program is returned to the head value (step 306).

Therefore, according to this embodiment, when the value of the input / output device is changed in the process of debugging, the operator does not need to record or store the changed portion, but only gives a scan re-execution instruction. Immediately restores the state of the input / output devices at the start of the scan, which makes it possible to repeat the scan of the sequence program under the same internal conditions, and reduces the number of man-hours required to check the state and check after debugging It is possible to return to the state before scanning without human intervention,
Particularly advantageous effects such as a reduction in debugging efficiency due to a work error can be obtained.

A second embodiment of the sequence program simulation apparatus according to the present invention is shown in FIGS. 5 is a functional block diagram of a sequence program simulation apparatus, FIG. 6 is a flowchart of a sequence program execution process, FIG. 7 is a flowchart of a memory area restoration process from a history, and FIG. 8 is a concept for explaining the contents of the history. FIG.

As shown in FIG. 2, even in the simulation apparatus of this embodiment, a debugger 101, an execution management unit 102a, a program execution unit 102b, a memory area 102c and a backup area 102d. For details of these functional elements, refer to the description of the corresponding items in the first embodiment.

The backup area history 103, which is a new functional element, corresponds to the history of the contents of the backup area 102d for a plurality of scans. The history 103 of the backup area is stored in, for example, the main memory or the auxiliary memory of the personal computer 10 as needed.

The re-execution instruction (10
In 1), the number of scans or input / output conditions of the memory area desired to be restored can be specified. That is, designation of a condition such as "memory area at the start of scanning in the n-th scan" or "memory area at the time of scanning when the input / output device changes to a specific state" can be performed in a predetermined command language. ing.

Next, referring to FIG. 6 to FIG. 8, the second step will be described focusing on the step execution processing and the scan re-execution processing.
A sequence program execution operation in the simulation apparatus 1 according to the embodiment will be described.

Even in this simulation apparatus, it is possible to simulate and execute a sequence program on a personal computer in one-step units. This is realized by executing the following series of processing.

As shown in the flowchart of FIG.
No scan re-execution instruction (NO in step 606)
Then, only the step execution processing (step 605) is repeatedly executed. Since the contents of the step execution processing are the same as those described above with reference to FIG. 4, redundant description is avoided. Also, in this simulation apparatus, the contents of the memory area 102 c are Is stored in the backup area 102d, and at the same time, a history 103 of the backup area is created.

As shown in the flowchart of FIG.
If it is determined that the start of the scan is made by referring to the contents of the program counter (YES in step 602), the contents of the memory area 102c at that time are stored in the backup area 1
02d (step 603). Subsequently, the contents of the backup area 102d up to that time are stored in the history 103.
Is additionally stored (step 604).

The memory area 102c is provided on condition that a predetermined operation (scan re-execution instruction) is accepted.
Is restored from the contents of the backup area stored in the history 103 of the backup area to the selected contents, and the execution address of the sequence program can be forcibly returned to the beginning of the program. This is realized by executing the following series of processing.

As shown in the flowchart of FIG.
During the execution of the step mode, a scan re-execution instruction (FIG. 2)
Is given (step 606 YES),
Data restoration processing from the backup area history 103 to the memory area 102c is performed according to the predetermined algorithm shown in FIG. 7 (step 607), and at the same time, the value of the program counter managing the execution address of the program is returned to the head value. (Step 608).

The details of the process of restoring the memory area from the history are shown in the flowchart of FIG. In the figure, in step 701, it is determined whether the memory area to be restored in the re-execution instruction is “when the designated scan” or “when the condition is satisfied”. Here, “at the time of the designated scan” means a case where a memory area to be restored by the scan is designated. Further, "when the condition is satisfied" means that a memory area to be restored according to a specific input / output state is specified.

As shown in FIG. 8, the backup area history 103 includes, for example, n pieces of memory contents (contents of the memory area 102c) MD0 to MDn. When the designation of, for example, the memory area at the time of the previous scan is performed, the memory content MD3 is restored correspondingly. In addition, each memory contents MD0 to MD
n includes an input data area, an output data area, and a control data area (counter, timer, etc.). Therefore, when a specific input / output is designated as a specific on / off pattern, such an on / off pattern is searched, and the memory content at the time of scanning that meets the condition is restored.

That is, if it is determined in step 701 that “when the condition is satisfied”, the data at the time of scanning satisfying the input / output condition is searched (step 703), and the searched memory area at the time of scanning is restored (step 703). 70
4). On the other hand, if it is determined in step 701 that "at the time of designated scanning", the memory area at the time of the scanning is restored (step 702).

Therefore, according to this embodiment, when the value of the input / output device is changed during the debugging process, the scan re-execution instruction can be specified at the time of scanning or the operator does not need to record or store the changed portion. Only by giving it together with the input / output condition designation, the state of the input / output device at the start of the corresponding scan can be immediately restored. For this reason, the simulation device is more convenient than the first embodiment.

Next, a sequence program execution operation in the simulation apparatus 1 of the third embodiment will be described with reference to FIGS. 9 to 11, focusing on step execution processing and step back processing.

Even in this simulation apparatus, it is possible to simulate and execute a sequence program in one-step units on a personal computer. This is realized by executing the following series of processing.

As shown in the flowchart of FIG.
No scan re-execution instruction (NO in step 905)
Then, only the step execution processing with step back function (step 904) is repeatedly executed.

At this time, as shown in the flowchart of FIG. 10, in the step execution process with the step-back function, the flag F2 indicating the step-back mode is reset (NO in step 1001). Step execution processing (step 1002)
-1007) are performed.

Further, even in this simulation apparatus, at the start of each scan, the contents of the memory area 102c are stored in the backup area 102d. this is,
This is realized by executing the following series of processes.

As shown in the flowchart of FIG.
If it is determined that the start of the scan is made by referring to the contents of the program counter (YES in step 902), the contents of the memory area 102c at that time are stored in the backup area 1
02d (step 903).

Further, on condition that a predetermined operation (scan re-execution instruction) is accepted, the memory area 102c
Is restored to the content at the start of scanning (at the start of program execution) stored in the backup area 102d, and the execution address of the sequence program can be forcibly returned to the beginning of the program. This is realized by executing the following series of processing.

As shown in the flowchart of FIG.
During the execution of the step mode, a scan re-execution instruction (FIG. 2)
Is given (step 905 YES),
The restoration process from the backup area 102d to the memory area 102c is performed (step 906), and at the same time, the value of the program counter managing the execution address of the program is returned to the head value (step 907).

Further, when a step back instruction is given, the contents of the memory area 102c are stored in the backup area 102d on the condition that a predetermined operation is accepted.
And the execution address of the sequence program is forcibly returned to the beginning of the program. Thereafter, the sequence program is forcibly restored until one step before the step at which the predetermined operation is received. A process for continuous execution is executed. This is realized by executing the following series of processing.

As shown in the flowchart of FIG. 10, when a step back instruction is given during execution of the step mode (step 1008 YES), the step back mode flag F2 described above is set (step 1009). Then, the determination result in step 1001 is YES. Therefore, the instruction execution process for one step (step 1010) and the step execution process of the program execution address (step 1011) are repeatedly executed. When the program execution address reaches a value one step before the step to which the step back instruction is given (step 1012: YES), the step back mode flag F2 is reset (step 1013),
The step back operation is completed.

As shown in FIG. 11, at this moment, at the moment when the step-back instruction is given at the address (8), the program returns to the address (0) which is the head of the program, and then sequentially. Address (1) to each step
The execution of a series of steps is completed instantaneously, despite the arrival at the address (7), which is the immediately preceding step, while executing (6). A state appears. Therefore, by repeating this step back instruction, the program can be substantially reversed. In particular, according to the equivalent reversion method, there is an advantage that reversion can be performed substantially without saving the results of the execution in each step.

Therefore, according to this embodiment, when the value of the input / output device is changed in the course of debugging, even if the operator does not record or memorize the changed portion, the value is changed to one.
The instruction execution can be restored to the state of the input / output device at the start of the scan while returning the instruction execution to the step-by-step feed, so that this kind of debugging work can be performed more efficiently.

[0080]

As is apparent from the above description, according to the present invention, when the value of the input / output device is changed in the course of debugging, it is necessary for the operator to not record or store the changed portion. Just perform simple operations according to
It is possible to immediately restore the state of the input / output device at the time of starting the scan, so that this kind of debugging work can be efficiently performed.

Further, according to the present invention, when the value of an input / output device is changed in the course of debugging, a simple operation can be performed by designating the number of scans without the operator recording or storing the changed portion. By simply performing the above, it is possible to immediately restore the state of the input / output device at the time of the start of the scan in the scans designated in the past scans, so that this kind of debugging work can be performed more efficiently.

Further, according to the present invention, when the value of the input / output device is changed in the debugging process, the input / output device and its state can be specified without the operator recording or storing the changed portion. By simply performing a simple operation, it is possible to immediately restore the state of the input / output device at the start of the scan in which the input / output device has changed to the specified value in the past scans. Debugging work can be performed more efficiently.

Further, according to the present invention, when the value of the input / output device is changed in the course of debugging, the operator does not need to record or memorize the changed portion, but only needs to perform a simple operation if necessary. The instruction execution can be restored to the state of the input / output device at the start of the scan while returning the instruction execution to the step feed step by step, so that this kind of debugging work can be performed more efficiently.

[Brief description of the drawings]

FIG. 1 is a configuration diagram (first embodiment) of a simulation device for a sequence program.

FIG. 2 is a functional block diagram of a sequence program simulation device (first embodiment).

FIG. 3 is a flowchart (first embodiment) of a sequence program execution process.

FIG. 4 is a flowchart of a step execution process.

FIG. 5 is a functional block diagram of a sequence program simulation apparatus (second embodiment).

FIG. 6 is a flowchart (second embodiment) of a sequence program execution process.

FIG. 7 is a flowchart of a memory area restoration process from a history.

FIG. 8 is a conceptual diagram for explaining the contents of a history.

FIG. 9 is a flowchart (third embodiment) of a sequence program execution process.

FIG. 10 is a flowchart of a step execution process with a step back function.

FIG. 11 is a conceptual diagram of a step-back operation.

[Explanation of symbols]

 Reference Signs List 1 simulation apparatus 10 personal computer 101 debugger 102 simulation engine 102a execution management unit 102b program execution unit 102c memory area 102d backup area 103 backup area history MD0-MDn memory area history

Claims (5)

[Claims] An apparatus for simulating a sequence program capable of executing a sequence program on a personal computer and stopping execution at an intermediate step, comprising: a data to be referred to when the sequence program is executed and a data to be set based on an execution result. A memory area for storing the contents of the memory area, a backup area for backing up the contents of the memory area, a memory contents storing means for storing the contents of the memory area in the backup area at the start of each scan, and a predetermined operation is received. Initialization means for restoring the contents of the memory area to the contents stored in the backup area, and forcibly returning the execution address of the sequence program to the beginning of the program. Return to the starting point and restart the scene program. Simulation apparatus of the sequence program which enables the line. 2. The apparatus according to claim 1, further comprising means for storing a history of the contents of the backup area for a plurality of scans, and wherein the initialization means stores the contents of the memory area in the history of the backup area for the number of scans specified from the history of the backup area. 2. The sequence program simulation apparatus according to claim 1, wherein the sequence program execution address is restored and the execution address of the sequence program is forcibly returned to the beginning of the program. And means for storing a history of the contents of the backup area for a plurality of scans, and wherein the initialization means stores the contents of the memory area in accordance with an input / output condition designated from the history of the backup area. 2. The sequence program simulation device according to claim 1, wherein the sequence program execution device restores the contents of the established scan times and forcibly returns the execution address of the sequence program to the beginning of the program. 4. A simulation apparatus for a sequence program, which is capable of executing a sequence program on a personal computer and stopping the execution in an intermediate step, wherein the memory stores data to be referred to and set when the sequence program is executed. An area, a backup area for backing up the content of the memory area, a memory content saving means for saving the content of the memory area in the backup area at the start of each scan, and on the condition that a predetermined operation is received, The contents of the memory area are restored to the contents stored in the backup area, and the execution address of the sequence program is forcibly returned to the beginning of the program. Thereafter, one step before the step when the predetermined operation is received, Until the sequence program And a re-execution means for connection executed, whereby the simulation apparatus of the sequence program and reproducible conditions equivalent to a state of being back one step execution scene program. 5. A recording medium for storing a computer program for realizing a sequence program simulation apparatus capable of executing a sequence program on a personal computer and stopping the execution of the sequence program in an intermediate step. Means for defining a memory area in which data to be set based on a reference object and an execution result is stored; means for defining a backup area for backing up the contents of the memory area; and A memory content storage means for storing the contents of the memory area in the backup area; and, on condition that a predetermined operation is received, restoring the contents of the memory area to the contents stored in the backup area, and an execution address of the sequence program. To the beginning of the program Recording medium comprising an initialization means, a return to manner.