JP2697074B2 - Programmable controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a programmable controller that executes a sequence control process and the like by using a level operation instruction and an edge operation instruction.

<Prior Art> The operation instructions executed by the programmable controller include a level operation instruction which is determined whether to execute depending on whether a current input is on or off, and an input in a previous cycle and a current cycle. There is an edge-type operation instruction that is executed when it changes (for example, when it is turned off last time or when it is turned on this time).

Usually, a program circuit is set in the programmable controller using these level-type operation instructions and edge-type operation instructions.

<Problems to be Solved by the Invention> As described above, for example, even if the same addition instruction is used, there are two types of instructions, that is, a level addition instruction and an edge addition instruction. As a result, the number of man-hours for instruction support increases and the memory area is used about twice, which is not efficient.

SUMMARY OF THE INVENTION An object of the present invention is to prevent a man-hour, a memory area, and the like of the instruction support from increasing even when a level-type operation instruction and an edge-type operation instruction are used, so that the efficiency of the entire apparatus does not decrease. The purpose is to:

<Means for Solving the Problems> The present invention adds an input determination process before an arithmetic process by using an accumulator for setting a current input state and a differential relay for holding a previous input state. The outline is as follows.

That is, the present invention provides a programmable controller having an input processing unit for inputting a level type operation instruction and an edge type operation instruction, wherein an accumulator in which a current input state is set and a differential in which a previous input state is held. The number of relays provided is equal to the number of occurrences of the edge type operation instruction. When the edge type operation instruction is given from the input processing unit, a rising edge of the input is detected from the contents of the accumulator and the differential relay, and the level type operation instruction Is replaced by an edge-type operation instruction.

<Operation> When the edge type operation instruction is set, the programmable controller of the present invention uses the accumulator for setting the current input state and the differential relay for holding the previous input state to determine the rise of the current input. Is detected,
The corresponding operation is executed using a level operation instruction instead of the edge operation instruction.

<Example> A programmable controller of the present invention will be described below.

As described above, the programmable controller of the present invention uses the accumulator Acc for setting the current input state.
And a differential relay that holds the previous input state.

Note that this differential relay is a special relay prepared in the system, and is installed as many times as the number of occurrences of the edge type operation command.

When, for example, a level type addition instruction is given from a program circuit input processing unit operated by the operator, the contents of the accumulator Acc are checked by the input instruction, and Acc = 1.
At the time of (ON), the level type addition instruction is executed and Acc = 0.
When (OFF), the level type addition instruction is not executed.

On the other hand, when the edge type operation instruction is given, the operation is performed as follows.

According to the input command, the current input state (ON 1 or OFF 0) is set in the accumulator Acc.

After this input command, an input determination process is performed. FIG. 1 shows the flow of this input determination processing.

The current input status set in the accumulator Acc,
Compares the specified contents of the differential relay that holds the previous input state. When the differential relay = 0 and Acc = 1,
It is determined that the current input has started, and the arithmetic instruction is immediately executed.

At this time, since the rising edge of the input has already been detected, the result is the same even if the operation is executed using the level-type operation instruction instead of the edge-type operation instruction.

If the differential relay is not 0 and Acc is not 1, it is determined that the current input has not risen, and the operation command is not executed.

When the above processing is completed, the current input state in Acc is stored in the differential relay, the content of the differential relay is updated,
The input determination processing ends.

Next, the operation concept of the present invention will be described in detail with reference to FIGS. 2 (a) and 2 (b).

FIG. 2A shows a level type addition instruction.

The operation processing Y001 = X002 + X003 for the input X001 is a level-type addition instruction. Such an instruction is converted into an object file as an input instruction (LD instruction) and an addition instruction (level type) by a compiler.

FIG. 2B shows an edge-type addition instruction.

The operation processing Y001 = X002 + X003 for the input X001 is an edge-type addition instruction. For such an instruction, an input determination instruction shown in the flowchart of FIG. 1 is set in the compiler after the input instruction (LD instruction). Next, an addition instruction (level type) is set, and an object file is generated.

Therefore, at the time of compiling, the operation instruction has only one form (level type) due to the input determination processing, and it is not necessary to separately process the edge type operation instruction and the level type operation instruction at the time of execution.

<Effects of the Invention> According to the programmable controller of the present invention, the following effects can be obtained.

Even if a program circuit is set using a level type operation instruction and an edge type operation instruction in the program circuit input processing unit, the edge type operation instruction is subjected to input determination processing at the time of compilation and is replaced with a level type operation instruction. So
Instruction support man-hours and memory area can be significantly reduced.

Conventionally, when the number of operation instructions is n, n level operation instructions and n edge type operation instructions have to be prepared, that is, a total of 2n operation instructions must be prepared. In this case, it is sufficient to prepare n level operation instructions for one input determination instruction, that is, n + 1 total instructions.

[Brief description of the drawings]

FIG. 1 is a flowchart of an input determination process in a programmable controller according to the present invention.
(B) is an operation conceptual diagram of the programmable controller of the present invention.

Claims (1)

(57) [Claims] An accumulator for setting a current input state and a differential relay for holding a previous input state in a programmable controller having an input processing unit for inputting a level-type operation instruction and an edge-type operation instruction. Are provided by the number of occurrences of the edge-type operation instruction, and when the edge-type operation instruction is given from the input processing unit, the rising of the input is detected from the contents of the accumulator and the differential relay, and the level-type operation instruction is detected. A programmable controller characterized by substituting edge type operation instructions.