JPH0638210B2 - Sequence controller input / output control system - Google Patents

Description

The present invention relates to an input / output control system of a sequence controller, and more particularly to an improvement of a direct / refresh input / output control system of a sequence controller.

[Prior Art] In the sequence controllers used in various automatic processing lines and component assembly lines, the sequence controller itself has been unitized in recent years.

FIG. 4 shows a conventional unitized sequence controller, in which various unitized circuit devices are detachably mounted on a sequence controller base (20).

In FIG. 4, each unit is a power supply unit (21),
It includes a CPU unit (22) and two input / output units (23) and (24), and it is possible to add a plurality of input / output units or attach a special unit to the sequence controller base (20) as required. .

Each unit (21) to (24) is easily attached to the base (20), and each input / output unit (23) is connected to the input / output bus provided in the base (20) in advance by a connector provided on the back surface. ), (24) and the CPU unit (22) or the power supply unit (21).

Therefore, according to such a unitized device, an input / output unit or other special unit is used as a base (2
There is an advantage that the sequence control can be easily changed or expanded by mounting the required number of the components in 0).

As described above, in a general sequence controller, when a given sequence program is executed, a signal is taken in from the input / output unit, the CPU performs the calculation, and this is output again from the input / output unit to the external device. The operation of doing is repeated.

Conventionally, there are basically two types of such input / output control methods, which are respectively known as a direct method and a refresh method.

The direct input / output method is shown in FIG.
Input (X) sequentially designated to execute the general sequence program shown in the ladder chart in the figure is taken in from the sequential input unit, and the output (Y) is sequentially stored in the image memory after the operation is performed. It has a structure in which the data is sequentially stored while being stored.

Therefore, according to the direct input / output method, in each sequence program, the input (X) is taken in, the operation is performed, and the output (Y) is directly output in each step, which is performed for each stage of the sequence program. All programs are executed repeatedly.

According to this direct input / output method, since the output for each program stage is performed each time, the processing speed can be increased in the individual stage, but the processing time until the whole program is completed becomes long as a whole. There was a drawback.

On the other hand, the refresh input / output method is shown in FIG. 7, in which all the signals are fetched in a batch, and the subsequent sequence program calculation is performed for each stage only inside the CPU unit. Once stored in the image memory. When the calculation of all programs is completed, the outputs stored in the image memory are collectively output from the output unit.

In FIG. 7, first, all inputs (X1) to (X200) are taken in, and all these inputs (X) are written in the image memory.

Then, the stored contents of the image memory are sequentially called for each stage, a desired calculation is performed, and the calculation result (Y) is again written in the image memory for each stage. After the calculation of all the programs is completed in this way, all the outputs (Y1) to (Y200) stored in the image memory are collectively output from the output unit.

According to this refresh input / output method, the acquisition and output of signals from the input / output unit are collectively performed, and the calculation of each program is performed only inside the CPU. Therefore, for example, the WAIT time required for the calculation of each stage is performed. Can be set shorter than the direct input / output method described above, and has the advantage of shortening the processing time of the entire sequence program, but on the other hand, since the signal output is batch output after the final calculation is completed, the first sequence The output in the program stage also has the problem that it has to wait until all the operations are completed.

[Problems to be Solved by the Invention] As described above, the conventional input / output method is fixed to either the direct or refresh method.
Due to the advantages and disadvantages described above, there is a problem that the sequence controller cannot always perform processing in an optimum state when handling various sequence programs.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide an improved input / output method capable of arbitrarily selecting an optimum input / output method according to the contents of a sequence program. is there.

[Means for Solving Problems] In order to achieve the above object, the present invention has a configuration in which either a direct method or a refresh method can be separately selected for a signal input method and a signal output method. It is characterized in that a maximum of four kinds of arbitrary input / output methods can be selected according to the sequence program by combining these input methods and output methods.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a time chart in the preferred embodiment of the present invention, which mainly shows the switching of the system for each of input and output.

In step (101), it is determined that the input method is specified as either direct or refresh,
The input hardware is switched to direct or refresh in steps (102) and (103) according to each method.

Similarly, in step (104), it is determined whether the output method is switched to direct or refresh, and in steps (105) and (106), the output hardware is switched to direct or refresh.

In step (107), the input method is determined again, and in the case of direct, the CPU is used because it is sequential input.
The relationship between the unit and the input unit is kept as usual, while when the refresh input method is selected in step (107), all the input from the input unit is transferred to the image memory of the CPU in step (108). Performs the action of inputting all at once.

Therefore, when the input refresh method is selected,
It is understood that all inputs are collectively stored in the image memory at step (108).

In this way, each input / output hardware is selected according to the designated method, and after the inputs are input collectively or sequentially, the desired calculation is performed in step (109).

That is, according to the direct method, the operation in step (109) is performed only for the first-stage input (X1) that is sequentially input, whereas according to the refresh method, the operations are collectively fetched. All programs (X1) to (X200) are continuously calculated, and the result is stored in the image memory.

On the other hand, while the calculation of (109) is being performed, the determination of the output method is further performed in step (110), and in the direct output method, a normal method in which a signal is output from the CPU unit to the output unit each time. However, when the refresh output method is selected, in step (111), switching is performed so that all outputs are collectively output from the image memory of the CPU unit to the output unit.

Therefore, the direct or refresh output according to the output method is executed even during the calculation in the step (109).

That is, in the case of input direct / output direct, the calculation in step (109) is originally processed in each program unit, and the output is directly output from the output unit each time, and the processing step repeats the loop again. , Input, calculation and output are performed for each stage.

Next, in the case of input refresh / output refresh, after all programs are collectively operated in step (109), all outputs stored in the image memory are output from the output unit as shown in step (111). Output all at once and complete all programs.

Further, according to the present invention, direct / refresh switching is performed separately for input and output, and in the case of input direct / output refresh, the calculation (109) is performed for each program. If the output method is determined to be refresh in (110), the total output (Y) stored in this image memory after the calculation of all programs is completed as shown in step (111) is step (111). Are collectively supplied to the output unit. That is, the input is sequentially input before this combination, and the output is a batch output after the calculation of all programs is completed.

Further, in the present invention, when the refresh input / direct output is selected, the calculation (109) is always repeated in sequence because all inputs are always stored in the image memory. The result (Y) calculated for each stage is stored in the image memory and is output from the output unit to the external mechanism each time.

In any combination of the methods, the WAIT time is selected to be long in the direct method and short in the refresh method.

Therefore, according to the arbitrary combination of the input / output methods of the present invention as described above, any optimum input / output method can be combined and selected for each sequence program, and particularly, the processing speed of the program can be improved or processed. It is possible to perform the program operation in the highest efficiency state.

FIG. 2 shows an example of direct / refresh switching means on the input side.

In the embodiment, the selection of the input method can be switched and selected by the user from the microcomputer (1) by means such as setting a switch or storing it in the memory, and the selection signal from the microcomputer (1) is input latch (2). ) Is remembered by.

The output of the input latch (2) becomes a "1" signal in the direct system and a "0" signal in the refresh system. This latch signal first switches between batch input and sequential input at the terminal (2a), and For the refresh input, the batch input is selected.

Similarly, the WAIT time is switched at the terminal (2b), and the WAIT time is selected to be long for direct input and short for the refresh method.

In addition, the input (X) in the operation of the program must be switched from the input unit in the direct method and from the content XIM of the image memory that has already been fetched in batch in the refresh method.
For this purpose, the output of the input latch (2) is directly supplied to the AND gate (3) and to the other AND gate (5) via the inverter (4).
The output of (5) is supplied to the operation input of the CPU unit via the OR gate (6).

Therefore, in the direct system in which the output of the input latch (2) is "1", the AND gate (3) is opened and the signal is taken from the input unit each time. In the refresh method, the input latch (2)
Is output "0", the AND gate (5) is opened, and the contents XI of the image memory already stored in batch
M will be taken in each time.

FIG. 3 shows an output system switching means. The above-mentioned switching signal of the microcomputer (1) is stored in the output latch (7), and when the direct output is selected, the output latch (7) immediately outputs. As a result, "1" is output, and as a result, the AND gate (8) is kept open, so that the operation result (Y) is stored as YIM in the image memory and at the same time as this storage, the output unit is output from the AND gate (8). Can be output one after another.

The output terminal (1a) of the microcomputer (1) performs batch and sequential switching on the output side, and similarly the terminal (1b) is a WAIT.
Outputs a signal to switch the time.

As described above, according to the present invention, either direct or refresh can be selected for each of the input and the output, and four different input / output methods can be arbitrarily adopted by combining them. You can

[Effects of the Invention] As described above, according to the present invention, the direct method and the refresh method can be arbitrarily selected for each of the input side and the output side, and the optimum input / output method for the sequence program can be selected. It has the advantage that the user can set it freely.

[Brief description of drawings]

FIG. 1 is a time chart diagram of a program calculation process in a preferred embodiment of the input / output control system according to the present invention.
The figure is a circuit diagram showing switching means on the input side in the present invention,
FIG. 3 is a circuit diagram showing the output side switching means in the present invention, FIG. 4 is a perspective view showing the general structure of a general sequence controller, and FIG. 5 is an explanatory diagram showing a direct input / output system. FIG. 6 is a partial explanatory diagram of a ladder chart showing an example of a general sequence program, and FIG. 7 is an explanatory diagram showing a conventional refresh input / output method.

Claims (1)

[Claims] 1. An input / output control method of a sequence controller in which a signal is input from an input unit and a desired calculation is performed by a CPU, and then a signal is output from an output unit to an external device, in which an input method is switched between direct and refresh. Includes switching means and output switching means for switching the output method between direct and refresh. When direct input, signals are sequentially captured from the input unit, the signals sequentially captured from this input unit are calculated, and the signal capture is also performed. The WAIT time at the time is changed to be long, and the signals from the input unit are collectively input at the time of refresh input, the signals thus collectively input are temporarily stored in the image memory, and the signals are fetched from the image memory at the time of calculation. Switching to set a short WAIT time When performing direct output, output the operation result one by one, and perform sequential output, switching is performed to lengthen the WAIT time at this time, and at the time of refresh output, the operation result is temporarily stored in the image memory and finally output at the same time as WAIT. An input / output control system of a sequence controller, characterized in that switching for shortening the time is performed, and direct / refresh switching of the input and output can be arbitrarily and independently executed.