JP3018790B2 - Programmable controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a programmable controller using an SFC command language system, and more particularly, to a programmable controller that can easily enter and return to a subprocess.

[0002]

2. Description of the Related Art Conventionally, various kinds of information to be controlled at a site, for example, physical information such as the number of products passing through an outlet of a belt conveyor reaching a predetermined quantity, or dangerous when a cutting machine is in operation. There is logical information such as detection of a moving object in the area. Programmable controllers (hereinafter, referred to as PCs) are widely used to perform predetermined output control (sequence control) according to the various information.

The method of programming the PC is completely different from ordinary computer programming. For example, as shown in FIG. 9, a symbol mark such as contacts 41 and 42 and a coil 43 used in the field before the PC was used. Connection diagram (ladder diagram) of the relay circuit is used.

Further, in recent years, a description format of an international standard (IEC SC65A / WG6) called SFC (Sequential Function Chart), which can easily display the control operation of the PC, is used as a program description method of the PC. I have. FIG. 10A is a conceptual diagram of the structure of the SFC program description. As shown in the figure, in the program, a description section called a step (STEP) and a description section called a transition (TRANSITION) are connected by a link (LINK).
TN21, S21, TN22,... The above steps S20, S21,... Each mean one stage (process) in a series of sequences (control programs), and have two states, active and inactive. Also,
Transitions TN21, TN22,... Represent transition conditions including branching and merging from the active step to the subsequent step. If the transition is on (the transition condition is satisfied), the PC selects the subsequent step, and if the transition is off, the PC determines that the subsequent step is not selected. Then, the shift is executed only when the selected subsequent step is inactive. When the transfer is performed, the transfer destination step is activated and the transfer source step is deactivated. These steps and transitions are described in a ladder diagram, which is developed mnemonically. FIG. 4B shows an example of a program that has been mnemonically expanded.

FIG. 11 schematically shows an arrangement in a case where the program described above is translated into a machine language and stored in a program memory. In the figure, a program of a transition section, a line section, and finally an action section are sequentially stored. PC
First, the program (A),
(B)... To output on / off information of each transition. Next, execute the program in the line section,
It outputs on / off of step transition instruction information (selection information) based on the on / off information of the transition. Next, the action part programs (C), (D),
(E) are sequentially read out, execution or non-execution is determined based on the step shift instruction information, processing or no processing (NOP processing) is performed, and the action unit reaches the end point. Then, the process of returning to the beginning and starting the processing of the transition section is repeated.

Generally, the above-described one round of processing is called one scan, and one scan forms one process. The user determines which part of the sequence control is divided as one process. The process includes a main process and a sub process, and the sub process has the same function as a subroutine in a normal program. In the SFC, when a similar process is repeatedly performed, a set of the repetitive processes is described as a subprocess, and the subprocess is called from one step, thereby simplifying the entire program. I have.

FIG. 12 is a conceptual diagram of the above sub-process call. In the figure, the execution order of the steps is indicated by a dotted line and an arrow. That is, in the figure, the sub-process 3 is called from the second step of the main process, and the sub-process 5 is further called from the second step of the sub-process. Then, the process returns to the calling step of the sub process 3 from the last step of the sub process 5, and returns to the calling step of the main process from the last step of the sub process 3. Therefore, the processing of the second step of the main process is to perform sub-processes 3 and 5. In the figure, the fourth step of the main process is similarly performed in the sub process 3
Therefore, the processing of the fourth step of the main process is also to perform the sub-processes 3 and 5.

[0008]

However, in the above-described conventional SFC program description, it is difficult to detect the presence or absence of the activation of other steps. Even if a step is active, it returns with the step remaining. For example, as shown in FIG. 13, when a sub-process describing return to the branch step S24 is created, this is mnemonically expanded as schematically shown in FIG. When the return (sub-process return) instruction of step S24 is executed, a problem occurs that the action processing of the subsequent steps is not executed.
In order to prevent such an inconvenience, in the conventional PC, for example, it is prohibited to program the return from the subprocess during the parallel branch as shown in FIG. 15, and one active step is performed except during the parallel branch. In addition, there is a constraint that the return step is arranged at the end of the sub-process so that there is no active step other than the return step of the sub-process. For this reason, there was a major problem that the degree of freedom in programming was impaired.

For example, at the site of sequence control, FIG.
As in the automobile manufacturing line shown in FIG. 6, there are cases where a plurality of different processes, namely, processing, painting, assembling 1 and assembling 2 are active at the same time. That is, it is necessary to simultaneously control a plurality of different manufacturing processes. In such a case,
In the SFC program description, the active step is always restricted to only one step, so that there is a problem that the process described in FIG. 17 in which processing, painting, assembly 1 and assembly 2 are sequentially described cannot be used.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a programmable controller capable of describing return from a subprocess without any restrictions.

[0011]

The present invention is applied to a programmable controller that operates by a main process and a sub process described in SFC.

FIG. 1 is a block diagram of the present invention. First, the activation detecting means 1 detects the presence or absence of an activated step other than the sub-process return step in the sub-process. The means comprises, for example, a counter.

Next, the return storage means 2 stores a return instruction in the sub-process return step. The means comprises, for example, a flag register. Then, the sub-process start instruction 3 initializes the activation detection means 1 and the return storage means 2 provided at the head of the sub-process.

Further, a sub-process end instruction 4 is provided at the end of the sub-process to detect the detection result of the activation detection means 1 and the storage result of the return storage means 2.

[0015]

According to the present invention, the activation detecting means 1 initialized by the sub-process start instruction 3 detects the presence or absence of an activated step in the sub-process other than the sub-process return step. The return storage means 2 initialized by (1) stores the return instruction of the sub-process return step. Then, the sub-process end instruction 4 detects the storage result of the return storage means 2 and the detection result of the activation detection means 1 to confirm that the return instruction is output at the final stage of the sub-process. It is recognized that there is an activated step other than the sub-process return step.

[0016] Thus, no matter where the sub-process return step is described, the subsequent action is executed, and when the sub-process returns, it is recognized whether there is an activated step other than the sub-process return step. Move to appropriate processing.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 2, in the present embodiment, when the mnemonic expansion of the SFC sub-process is performed, the sub-process start instruction 23
A sub-process end instruction 24 is provided at the end of the sub-process. In the process of executing the sub-process, the counter 21 and the flag SRET 22 shown in FIG. 3 are used. Counter 21 is incremented each time recognizes that step is active during the action part execution "2" _{(Q D, Q c, Q} B, the output of Q _A is "001
0 "). The flag SRET3 is set to "1" when the sub-process return step of the action section is active.

Next, the operation of this embodiment having the above configuration will be described with reference to FIG.
This will be described with reference to flowcharts shown in FIGS. In addition,
These processes are executed by a microprocessor (not shown).

FIG. 4 is a flowchart of the processing operation of the sub-process start command. In the figure, at the start of the sub-process, first, the flag SRET is cleared to "0" (process S41). As a result, the flag SRET is initialized.

Subsequently, the signal CLR is set to "L" level (step S42), and then the signal CLR is set to "H".
The level is set (process S43). Thereby, the counter 2
1 is initialized to "0".

Thereafter, the transition section is executed, and the line section is executed. Subsequently, in the execution of the action unit, the processing shown in the flowchart of FIG. 5 is executed. That is, for each step relay (bit memory indicating whether the step is active or inactive), it is determined whether or not the switch is on (step S51).

If it is determined that the step relay is on, the signal CLK is set to the "H" level (step S52), and then the signal CLK is set to the "L" level (step S53).
Thus, if the step relay is on, that is, if the step is active, the counter 21 is counted up.

Subsequently, an action unit process is performed (process S
54). As described above, two or more activated steps are detected. In step S51, if the step relay is off, the process immediately proceeds to step S54. In this case, no processing (NOP processing) of the action section is executed.

FIG. 6 is a flowchart of a sub-process return (return) process. In the figure, in the sub-process return process, first, it is determined whether or not the step relay is on (process S61).

If it is on, it is determined that sub-process return is instructed, and the flag SRET is set to "1" (step 62). As a result, the return of the sub-process is recognized in the sub-process end processing described later.

In step S61, if the step relay is off, the process is immediately terminated. This allows
Unless a sub-process return is instructed, the sub-process return is not recognized in the sub-process end processing described later.

FIG. 7 shows a flowchart for ending the sub-process. In the figure, the sub-process end process first determines whether the value is “1” by referring to the flag SRET (process 71).

In this determination, if the flag SRET is "1", it is determined that the sub-process return has been instructed. In this case, the value of the counter 21 is subsequently referred to, and in the sub-process return, the sub-process return step is executed. It is determined whether there is another active step (step 72).

If the value of the counter 21 is "1", it is determined that the activation step is only the sub-process return step, and the sub-process is returned (returned) (step 73). If the value of the counter 21 is “2”,
It is determined that there is at least one active step other than the sub-process return step, and in this case, error processing is performed (step 74). In this process, if the presence of two or more active steps is permitted in advance, another process corresponding to that case is performed.

As described above, the processing is performed. For example, in the case of the SFC description shown in FIG. 8, the activity is detected in step S12 (the black triangle mark at the upper left corner of the step symbol indicates that the activity step is active). Shown), counter 21
Becomes “1”, and in step S14, the counter 21
Is incremented to “2”. Step S14 is a sub-process return process. Since the process is active (the step relay is on), the flag SRET is set.
Is set to “1”. As described above, the execution of the action unit is completed, and the process of terminating the sub process shown in the figure is executed. In this case, the flag SRET = 1, and
In addition, since the counter 21 ≠ “1”, it can be detected that there is an active step other than the sub-process return step. Therefore, error processing and the like can be performed as needed.

Further, even if the sub-process return step is not located at the end as in the SFC description shown in FIG. 13 (see FIG. 2 for the mnemonic expansion), first, the counter 21 = “ 0 ”and the flag SRET =“ 0 ”, and in the action part process, the counter 21 is set to“ 1 ”in step S24 in the middle of the action part.
And the flag SRET becomes "1". After the subsequent action section is executed, in the last sub-process ending process, when only the sub-process return step S24 is active, SRET = “1” and the counter 21 = “1”. Therefore, the process S7 of FIG.
3 is executed, and it is possible to easily return from the sub process to the main process.

[0032]

According to the present invention, even if the sub-process return step described in the SFC is described at an arbitrary position in the sub-process, the sub-process return is stored and the action after the sub-process return step is always executed. In addition, since an active step other than the sub-process return step is detected, it is possible to easily describe the return of the sub-process without any restrictions.

[Brief description of the drawings]

FIG. 1 is a block diagram of the present invention.

FIG. 2 is a diagram illustrating mnemonic expansion according to the present embodiment.

FIGS. 3A and 3B are diagrams illustrating a partial configuration of the present embodiment.

FIG. 4 is a flowchart (part 1) of the embodiment.

FIG. 5 is a flowchart (part 2) of the present embodiment.

FIG. 6 is a flowchart (part 3) of the present embodiment.

FIG. 7 is a flowchart (part 4) of the present embodiment.

FIG. 8 is a diagram illustrating an example of an SFC description in the embodiment.

FIG. 9 is a diagram showing an example of a ladder diagram.

FIG. 10A is a conceptual diagram illustrating the configuration of an SFC description;
(b) is a diagram showing an example of a mnemonic-expanded program.

FIG. 11 is a schematic diagram illustrating an SFC program arrangement.

FIG. 12 is a conceptual diagram of a sub-process call.

FIG. 13 is a diagram illustrating an example of a sub-process return description.

FIG. 14 is a schematic diagram in which the SFC description of FIG. 13 is mnemonically expanded.

FIG. 15 is a diagram illustrating an example of a parallel branch.

FIG. 16 is a diagram showing an example of an automobile production line.

FIG. 17 is a diagram showing an example in which description by the conventional SFC is impossible.

[Explanation of symbols]

 1 Sub-process start command 2 Detecting means 3 Return storage means 4 Sub-process end command

Claims (1)

(57) [Claims] 1. A programmable controller over roller which is operated by the main process and the sub process described in SF C, activation detection means for detecting the presence or absence of steps that are activated other than subprocess returns step in said sub-process (1) a return storage means (2) for storing a return instruction in the subprocess return step; and an activation detection means (1) and a return storage means (2) provided at the head of the subprocess. A sub-process start command (3) provided at the end of the sub-process, and a sub-process end command (3) for detecting a detection result of the activation detection means (1) and a storage result of the return storage means (2). 4 and) have activity recognized in the sub-process end command (4)
Of the detection result of the conversion detection means (1) and the return storage means (2)
A programmable controller, which performs a predetermined process based on a storage result .