JPH0654443B2 - Sequence processing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sequence processing method capable of smoothly performing mutual processing between a microcomputer included in a sequence controller and an external device.

[Prior art]

As a conventional sequence processing method of this type, there is a method in which a sequence controller having the configuration shown in FIG. 1 is used by a program similar to a Neumann type computer. In FIG. 1, 1 is a sequence controller, 1
a is a microprocessor (hereinafter referred to as CPU) that executes computations, 1b is a program storage unit in which steps of sequence processing are stored, 1c is a data storage unit, 1d is a CP
An output unit showing an interface unit when the U1a requests the external device 2 for processing, and 1e is a CPU 1a from the external device 2
Is an input section indicating an interface section when receiving information, and 3 is a peripheral device.

As a sequence processing method of the sequence controller having the above configuration, there are the following methods conventionally. The contents programmed in advance are stored in the program storage unit 1b, and the CPU 1a reads the input information from the external device 2 via the input unit 1e in order from the beginning of the step in accordance with the procedure of this sequence program. The process of executing the operation under this condition and writing the output information to the external device 2 through the output unit 1d is cyclically repeated, that is, if one cycle is from the beginning to the end of one sequence program, that cycle is There is a processing method of repeating continuously. However, in this method, an instruction to read input information from one device of the external device 2 or to write output information is executed only once in the above-mentioned one cycle. For example, after reading the input information in the first cycle, If the input information changes immediately, the time to read this change is the second time after one cycle.
It is the time to read the input information of the cycle, and the CPU 1
A maximum delay time of 1 cycle occurs until a is recognized.

In order to improve the delay time, the sequence program is provided with a plurality of the same commands for reading the specific input information. However, in this method, in a sequence program having a long one cycle time, the time of one cycle time is greatly extended, and the improvement effect may be diminished.

Since the conventional sequence processing method is configured as described above, the time from the sequence controller requesting processing to an external device until recognizing the next processing is influenced by the 1 cycle time of the sequence program, and the recognition time. However, there were drawbacks such as delay in processing and quick processing.

[Outline of Invention]

The present invention has been made to eliminate the above-mentioned drawbacks of the conventional ones. When the sequence controller makes a processing request to an external device, the sequence process is temporarily stopped, and the completion of the process is interrupted from the external device by a process interrupt. An object of the present invention is to provide a sequence processing method capable of speeding up the processing time by allowing the sequence processing to be continuously executed from the pause position at the time of recognition.

Example of Invention

An embodiment of the present invention will be described below with reference to FIG. FIG. 2 shows a device configuration of a sequence controller used in the system of the present invention, in which the same reference numerals as those in FIG. 1 denote the same components. Reference numeral 1g indicates a monitoring timer for which a predetermined time period is set.

Next, the operation of the embodiment having the above configuration will be described with reference to FIGS. FIG. 3 is a flow chart showing the outline of the sequence processing method of the present invention, and FIG. 4 is an explanatory view of the same operation. First, the sequence controller 1 is initialized and the sequence starts [FIG. 3].
A process is started [Fig. 3], and in the execution process [Fig. 3] of the process, the external device 2 is notified for the purpose of complicated control process, communication with other system, reference of contents of external storage device, etc. It becomes necessary to make a processing request [FIG. 13]. This processing request can be made by issuing an interrupt processing request from the CPU 1a to the external device 2 through the output unit 1d. As shown in FIG. 4, the CPU 1a sets an internal flag and a monitoring timer 1g. Then, the counting is started from the set predetermined time period. After this C
The PU 1a temporarily suspends the sequence processing which is being executed [FIG. 3], keeps the reset of the internal flag, and checks the time-up of the monitoring timer 1g. On the other hand, the external device 2 requests the above processing [FIG. 3].
Then, the required processing is started [Fig. 3] and when this processing is completed [Fig. 3], the input unit 1e is input to the CPU 1a.
Generate a process interrupt via. At this time, CPU1
a is an external device 2 by resetting the internal flag.
Recognize that the process of is completed. CPU1 by this recognition
In step a, the sequence processing which has been temporarily stopped is restarted from the stop position and continued [FIG. 3]. After this continues
Sequence controller 1 performs necessary processing [FIG. 3 (FIG. 19)]
Then, one cycle of the sequence processing is completed. However, in the above processing, a processing request to the external device 2 [3rd
13] After that, the CPU 1a indicates that the monitoring timer 1g has timed out before the completion of the external device 2 [FIG. 16].
If the request is received, the external device 2 is requested to stop the process execution in order to abandon the process request, and the sequence process is continued from the temporary stop position [FIG. 3].

Although the sequence controller is provided with the monitoring timer 1g in the above embodiment, the time-up may be performed by creating a timed program for the CPU 1a, and the same effect as that of the above embodiment can be obtained.

〔The invention's effect〕

As described above, according to the present invention, when the sequence controller uses the external device in the process of the sequence processing, the sequence processing is temporarily stopped from the processing request to the external device until the completion of the processing is recognized. Since it is configured as described above, the completion of processing of the external device can be recognized very quickly without being affected by the 1 cycle time of the sequence program,
Further, even if the completion of the processing is delayed, the delay can be prevented by the predetermined time limit of the monitoring timer, so that there is an effect that a very excellent sequence processing method with good processing efficiency can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a sequence controller used in a conventional sequence processing system, FIG. 2 is a block diagram showing a sequence controller used in the sequence processing system of the present invention, and FIG. 3 is a sequence processing system of the present invention. FIG. 4 is a flow chart showing an outline of the flow, and FIG. 4 is an explanatory view of the same operation. DESCRIPTION OF SYMBOLS 1 ... Sequence controller, 2 ... External device, 1a ... Microprocessor, 1g ... Monitoring timer, 12 ... Processing, 1
3 ... Processing request to external device, 14 ... Sequence stopped,
16 ... Processing completed, 17 ... Time-up completed, 18 ... Sequence continued. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A sequence processing method comprising a sequence controller having a microprocessor and a monitoring timer, and an external device for inputting and outputting data through an interface with the sequence controller, wherein the sequence controller executes the sequence processing while the external device is operating. When it becomes necessary to cause the device to perform a specific process, a timer is activated for the monitoring timer set for a predetermined time, and at the same time as the timer is activated, the external device is requested to perform the specific process. From the point of time, the sequence processing is temporarily stopped, and the earlier time of the point when the microprocessor receives the processing completion of the external device during the pause or the point when the monitoring timer reaches the preset time limit. At the time point of The sequence processing method to be open.