JPH07120170B2 - Decoding processing method of programmable controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a sequential function chart (hereinafter referred to as “sequential function chart”).
SFC) is used for the decoding processing method of the programmable controller.

[Conventional technology]

Conventionally, the decoding processing method of this kind of programmable controller is such that if there are several active steps that must be decoded within one scan, the decoding order is completely random or the step number It is performed from a younger person, and there is used a method in which it is not clearly managed which steps have already been decoded and which steps have not been decoded within one scan.

[Problems to be Solved by the Invention]

Next, referring to FIG. 4, disadvantages that may occur when processing a simultaneous merging connection (a connection in which all connected steps are active as a step condition) according to a conventional decoding processing method example Will be explained.

In the figure, the connection status of each step 001 to 005 is shown in FIG. (A). Steps 001, 003 and 004 are all active, and if the transition condition 201 is satisfied, they are merged at the same time to step 005.
You can step into. It should be noted that the steps shown by diagonal lines indicate that they are in the active state. That is, in the current scan, steps 001, 002, and 004 are targets for decoding. Therefore, step 001 is first decoded, but since it is a simultaneous merging connection, it is also checked at the same time whether or not steps 003 and 004 are active (Fig. (B)). In this case, the step
Since 003 has not been activated yet, step 001 cannot proceed and the active state is continued. Next, when step 002 is decoded and the transition condition 200 is satisfied, the process proceeds to step 003, and step 003 shifts to the active state (FIG. (C)). Next, when Step 004 is decoded, Steps 001 and 003 are already in the active state, so if the transition condition 201 is satisfied, the step condition for simultaneous merging connection is satisfied, and immediately after the decoding of Step 004, Step 005 is made active to prepare for the next scan (Fig. (D)). That is, in the present case, the result is that the step 003 is skipped during one scanning and the step 002 to the step 005 are advanced by two steps.

As shown in this example, in the conventional decryption processing method, the decryption order of the steps is random, and the decrypted and undecrypted steps are not managed, so there is a possibility that two steps will occur in some cases. Also, in the case of simultaneous merging connection, all the steps to be merged are decoded one by one, and the same step is repeatedly decoded, resulting in waste of processing time. There is a drawback that.

[Means for Solving the Problems]

The programmable controller decoding processing method of the present invention corresponds to the first and second step number storage tables and the operation circuit to be decoded during the current scanning period stored in the first step number storage table. The step number to be stepped is sequentially taken out, the operation circuit corresponding to the step number is decoded, and the step number of the step to be advanced when the operation circuit can be advanced, and the current step number when the operation circuit cannot be advanced. Means for storing step numbers in the second step number storage table, respectively, in the order of scanning, and transferring the contents of the second step number storage table to the first step number storage table each time scanning is completed. Means and the operation circuit of the step number that is connected together at the same time are decoded and the operation circuits of the subsequent step numbers are decoded at the same time. It has means for displaying the completion of processing in the subsequent step number column and prohibiting reprocessing of the step number.

[Action]

The first and second step number storage tables are provided in the logic decoding unit of the programmable controller using the SFC, and the steps in the active state in the scan stored in the first step number storage table are sequentially taken out. The step number of the step ahead is decoded and stored, and if the step is not possible, the step number of the current scan is stored in the second step number storage table, respectively. When the step of connection is decoded and stepping is not possible, the completion of processing is displayed in the other step number column decoded at the same time, and when one scanning is completed, the content of the second step number storage table is changed to the first step. Transfer to the step number storage table. Therefore, in the SFC decoding, the decoding order of each step for each scan can be made orderly by a fixed order, and the management of the completed steps and the unprocessed steps is clear and has two steps. Stepping can be prevented, and in particular, in the step processing of the simultaneous merging connection, useless double processing can be omitted, and the processing time can be greatly shortened.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of step number storage tables 1 and 2 used in one embodiment of the programmable controller decoding processing system of the present invention, and FIG. 2 is a connection for branching from step 001 to three steps 002, 003, 004 simultaneously. FIG. 3 is an explanatory diagram of the configuration and the processing procedure in this case, and FIG. 3 is an explanatory diagram of the configuration in which three steps 001, 003, and 004 are simultaneously joined and connected, and the processing procedure in this case.

The step number storage table 1 (hereinafter referred to as table 1) is a step number column 2 for storing the step number of the operation circuit which is activated for decoding during the current scan.
And the MSB column 3 at the left end of the table, the MSB column 3 is a step number column for a step to be decoded at the same time during decoding of a certain step in the case of simultaneous merge connection processing. This is a field for setting a processing completion flag. In the step number storage table 4 (hereinafter referred to as the table 4), among the step numbers of the table 1, the step number of the next step ahead of the step number which is allowed to be stepped, or the step number which is not allowed to step is shown. As it is, it is stored in the step number column 5 in the processing order.

Next, the processing operation according to this embodiment will be described with reference to FIGS. 2 and 3.

A programmable controller (not shown) takes out step numbers from the top of Table 1 in sequence starting from the start step at the start of scanning, decodes whether this step can be stepped, and if it can step, the step number of the step destination. If it is not possible to step, the current step number is stored in the table 4. After decoding all the steps stored in Table 1 (SFC in one scan
(End of decoding), the contents of table 4 are transferred to table 1, and the same processing is performed in the next scanning. That is, once the decryption order is fixed, the decryption can be automatically executed in the regular order. In addition, since all the steps which have been decoded are transferred to the table 4 regardless of whether or not they are stepped, it is impossible that the decoding is performed twice during one scanning (two-step stepping). here,
Although there is more than one active step in the SFC, there is a simultaneous branch connection (simultaneous sequence of branching from one step to several steps in one scan). This is only the case, and the processing in this case will be described with reference to FIG.

Table 1 now stores step 001, which is active for the current scan, and as a result of decoding, transition condition 1
If 00 is established, it is a simultaneous branch connection that branches to steps 002, 003, and 004, so step numbers 002, 003, and 004 are stored in the table 4 in order from the left side of the connection configuration. In this way, when this connection is made, for example, if it is stored in the table 4 in order from the step on the leftmost side, after that, it will be decoded in order from the one on the left as seen from the overall SFC flow. The decoding order will be neat and tidy.

Finally, the processing in the case of simultaneous merging connection will be described with reference to FIG.

Steps 001 to 005 have the same connection configuration as in the case of the conventional example shown in FIG. 4A (FIG. 4A), and in this case, the processing completion flag of the MSB column 3 of the table 1 is used. . This flag is dedicated to simultaneous merging connections,
It is always "0" when there is no simultaneous merging, and does not affect other processing. The table 1 stores the step numbers 001, 002 and 004 of the steps which are active in the current scan (Fig. (B)). First, when deciphering step 001, step 003 and 004 are always checked. Since step 003 is not yet active, the step condition for simultaneous merging is not satisfied, and step number 001 and step number 004 are also stored in table 4 at the same time. To do. At this time, in order to indicate that step 004 has already been processed, the MSB column 3 of the address in which the step number 004 of table 1 is stored is set to "1" (Fig. (C)). next,
When step 002 is decoded and transition condition 200 is satisfied, step 003, which is the next step, is stored in table 4 (FIG. 4 (d)). The decoding of step 004 is not executed in this scan because the MSB column 3 is set to "1", and there is no waste of checking the same simultaneous merging step twice. This simplification is allowed because of the nature of the simultaneous merging connection, which does not advance in the previous scan unless all the steps connected to it are active. The problem here is that the above process partially disturbs the decoding order, but this will affect the whole because if it advances to step 005 in the next scan, it will be decoded in the correct order. Does not give. In the case of the above-mentioned conventional example, the wasteful process is performed only once, but the more steps are connected, the more effective the present invention becomes.

〔The invention's effect〕

As described above, according to the present invention, when decoding the SFC by the programmable controller, two step number storing tables for storing the steps are prepared, and one table is provided with the processing completion flag for the step of the simultaneous merging connection. By having this, there is an effect that the order of decoding the steps can be made orderly, the processing time in the case of the simultaneous merging connection can be significantly shortened, and the two-step stepping can be easily prevented.

[Brief description of drawings]

FIG. 1 is a block diagram of step number storage tables 1 and 2 used in one embodiment of the programmable controller decoding processing system of the present invention, and FIG.
Connection configuration that branches to 002, 003, 004 steps at the same time,
Illustration of the processing procedure in this case, FIG. 3 shows three steps
FIG. 4 is an explanatory diagram of a configuration and a processing procedure in the case where 001, 003, and 004 are simultaneously merged and connected, and FIG. 1,4 …… Step number storage table, 2,5 …… Step number column, 3 …… MSB column, 001 to 005 …… Step number (or step), 100,200,201 …… Transition condition.

Claims (1)

[Claims] 1. A decoding process of a programmable controller that decodes an operation circuit that constitutes a unit of control for each scanning period by using a sequential function chart to determine whether a step can be stepped, and then performs the next scanning again. In the method, the first and second step number storage tables and the step numbers corresponding to the operation circuit to be decoded during the current scanning period stored in the first step number storage table are sequentially extracted, The operation circuit corresponding to the step number is decoded, and when the operation circuit can be stepped, the step number of the step destination, and when it cannot be stepped, the current step number is set in the scanning order. A means for storing in the step number storage table of No. 2 and the contents of the second step number storage table every time the scanning is completed. When the operation circuit of the step number connected to the step number storing table and the operation circuit of the step number connected at the same time are decoded and the operation circuits of the subsequent step numbers are simultaneously decoded, the processing is performed in the step number column after that. A decoding processing method for a programmable controller, comprising means for displaying completion and prohibiting reprocessing of the step number.