JPS6388602A - Operating method for sequence control - Google Patents

Abstract

PURPOSE:To smoothly continue to execute a program at the time of an instantaneous power failure or the restarting time after a power source is cut off by storing a program step during the present execution immediately before a power source voltage is reduced to an unoperatable voltage. CONSTITUTION:A microprocessor 8 of a CPU unit 2, while the power source voltage of a power source unit 1 is always monitored by a voltage detecting circuit 7, receives and transmits the control signal of respective interface units 3-6. At the CPU unit 2, a memory 9 to store a step at the time of the power source reduction is provided and at the memory 9, an operating voltage from a back-up power source 10 including a battery, etc., is always supplied. Consequently, even when the power source voltage of the power source unit 1 is reduced, the memory 9 of the CPU unit 2 can store and hold a step instructed by the microprocessor 8. Thus, at the time of restarting the execution of the program, the step immediately before the voltage is reduced is read and from the step, the execution of the program can be restarted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of operating a sequence controller, particularly to an improvement in stopping and restarting operation when the power supply voltage drops.

[[Prior Art] Sequence controllers are used in a wide range of industrial fields to accurately control or monitor production equipment in which many machines are combined, such as various automatic processing lines, parts assembly lines, etc. By automating the sequence control of the target, complex and advanced control is possible.

In particular, in recent years, control objects such as computers,
Devices or robots are organically connected,
In addition to sequentially controlling these devices, highly functional sequence control is required for monitoring the entire line, detecting abnormalities, tracking, positioning, and measuring.

A sequence program consisting of a plurality of steps is created in advance in accordance with the control process of the sequence controller or the controlled system, and a desired control action is performed by sequentially executing this program.

[Problems to be Solved by the Invention] However, in the conventional sequence controller, when the power is turned on, the sequence program consisting of a plurality of steps is always executed from the O step, that is, from the beginning of the program.

Therefore, if the power is temporarily turned off due to a momentary power outage or a drop in the power supply voltage due to a power cut while a program is running, the interrupted sequence program will be restarted when the power is turned on. Also, the sequence program always starts its execution from the initial 0 step, and at this time the controlled system has already progressed to the middle control step, so in such a case, the sequence controller's control will be changed before and after the instantaneous power outage. becomes irregular,
In some cases, there is a drawback that a completely unexpected control sequence or loss of control may occur.

In particular, if the sequence program includes a counter that counts according to the progress of the control process, the count value of the counter and the program steps may not match when restarting, and the program may not be able to be executed. There were cases where it happened.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide an improved sequence controller operating method that allows program execution to continue smoothly even when restarting after a momentary power outage or power cut. be.

[Means for solving the problem] In order to achieve the above object, the present invention detects a drop in the power supply voltage supplied to the CPU unit, and immediately before the power supply voltage drops to an inoperable voltage, the current execution program steps are stored, then execution of the program is stopped, and when the operation is restarted, the stored steps are read out and the CPU
The unit is characterized by restarting execution of the sequence program from this step.

[Example] Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the overall configuration of a sequence controller to which the operating method according to the present invention is applied, and as is well known, the sequence controller includes a power supply unit (1), a C
It includes a PU unit (2) and a plurality of input/output units, namely a keyboard interface (3), an I10 interface (4), (5), and (6).

Therefore, the CPU unit (2) executes a predetermined sequence program using the power supply voltage supplied from the power supply unit (1), and the I10 interface unit ( 4), (5).

(6), and also exchanges signals with the keyboard unit (6).
3) The desired program control is performed using the operation signal from 3).

The characteristic feature of the present invention is that the CPU unit (2)
monitors the power supply voltage of the power supply unit (1), detects this voltage drop when the power supply voltage drops due to a momentary power outage or power cutoff, and stores the step currently being executed just before the power supply voltage reaches the inoperable voltage. Then, the program execution is stopped, and when the program execution is resumed, the step immediately before the voltage drop is read and the program execution is resumed from this step.

In FIG. 1, a CP is used to monitor the power supply voltage.
The U unit (2) is provided with a voltage detection circuit (7), and the microprocessor (8) of the CPU unit (2) is provided with a voltage detection circuit (7).
) is the voltage detection circuit (7) that detects the power supply voltage of the power supply unit (1).
) performs control signal exchange with each of the above-mentioned interface units (3) to (6) while constantly monitoring.

Further, the CPU unit (2) is provided with a memory (9) for storing the steps at the time of the power supply drop described above, and this memory (9) contains the power supply unit (1).
) is constantly supplied with operating voltage from a backup power source (10) including a battery or the like provided independently.

Therefore, even if the power supply voltage of the power supply unit (1) drops, the memory (9) of the CPU unit (2) can store and retain the steps instructed by the microprocessor (8).

FIG. 2 shows the operating state of this embodiment when the voltage drops.

The voltage detection circuit (7) in the embodiment is connected to the power supply unit (1
) monitors the DC voltage of the CPU unit (2
), a 5V DC voltage is supplied from the power supply unit (1), and normally this voltage passes through the voltage detection circuit (7) and is directly applied to the microprocessor (8). ing.

At time t1 in FIG. 2, the power supply voltage of the power supply unit (1) drops 17 due to a temporary power outage or power cutoff, and the predetermined reference voltage VTH reaches, for example, 4.8■, which also indicates the timing, and this 4.8V is the power supply voltage of the CPU unit. Although this voltage is sufficient for program control in (2), when the power supply voltage drops to a predetermined value below this, for example, about 4.5V, program control by the CPU unit (2) becomes impossible.

Therefore, at time t1, with the control action fully performed, the microprocessor (8) receives the voltage drop signal (100) from the voltage detection circuit (7) and this signal (100).
One-shot output (1
01), a predetermined step is executed in the CPU unit (2).
Memorize the number of knobs and stop the program.

As shown in FIG. 2, according to this embodiment, upon detection of the voltage drop signal (101), the microprocessor (8) stores the currently executed step in the memory (9), and also stores the step currently being executed. The program execution of the CPU unit (2) is stopped at time t2, which is slightly later than t1.

Therefore, it is understood that at time t2, the program control of the controlled system is completely stopped.

In this execution stopped state, the power supply voltage of the power supply unit (1) is lower than the operable voltage, which is usually OV, but even in this state, the execution immediately before the operation interruption stored in the memory (9) is performed. The step is the backup power supply (10
) is stored in memory.

The instantaneous power outage or power interruption mentioned above is restored in a short time or at a predetermined period, and when operation is resumed at time t3 in FIG. 2, operation is immediately resumed automatically or by a start signal from the keyboard unit (3). When instructed, the microprocessor (8) first reads the number of steps stored in the memory (9), and the program is restarted from this read number of steps.

At this time t3, the power supply voltage of the power supply unit (1) has already recovered to a voltage sufficient for the control action, and the CP
The U unit (2) can resume program control from the step immediately before interruption, and as a result, program execution is resumed continuously while using the count value of the counter counted by the sequence program, etc. It happens.

When the microprocessor (8) reads the storage step in the memory (9) at the start time t3, the memory (9)
) is reset and ready for the next power supply voltage drop immediately.

Therefore, according to the present invention, even if the operation is interrupted due to a drop in the power supply voltage, program control is resumed from the step immediately before the interruption when the operation is resumed, and there is an advantage that there is no misalignment or other problem in the execution of the program. have

Of course, the memory (9) can store not only steps but also, for example, a predetermined count value for sequence calculations, etc., or in the present invention, such a memory for sequence calculations can be It is also possible to provide it separately from the memory (9).

Further, in the present invention, the backup power source (10)
In addition to ordinary batteries, it is also possible to temporarily use the charging voltage of capacitors in case of momentary power outages.

Furthermore, the voltage detection circuit (7) is capable of monitoring not only the DC voltage supplied from the power supply unit (1) but also the input AC voltage of the power supply unit (1), typically an AC voltage of 100V.

[Effects of the Invention] As explained above, according to the present invention, even when an operation is interrupted, the sequence program is not restarted from the initial O step, and when the operation is restarted, the operation is restarted from the step immediately before the interruption. As a result, even if there is an interruption, the execution of the sequence program continues before and after the interruption, ensuring that unexecutable or inconsistent execution of the program is eliminated. becomes possible. 4゜ Final explanation of the drawings Fig. 1 is a schematic configuration diagram of the Siegen controller to which the operating method according to the present invention is applied, and Fig. 2 shows the control action of the present invention before and after the operation is interrupted in Fig. 1. It is a timing chart figure.

Identical parts in each figure are given the same reference numerals, and 1) is a power supply unit;
(2) is a CPU unit, (3) to (6) 1.10
interface unit, (7) is a voltage detection circuit, (
8) is a microprocessor, (9) is a memory, (10)
is a backup power source.

Claims (1)

[Claims] (1) In a method of operating a sequence controller that sequentially executes a predetermined multi-step sequence program to sequentially control a controlled system, a drop in the power supply voltage supplied to the CPU unit is detected and the power supply voltage is activated. It memorizes the program step currently being executed just before the voltage drops to the disabled voltage, then stops the program execution, reads out the memorized step when restarting operation, and
A method for operating a sequence controller, characterized in that the PU unit resumes execution of the sequence program from this step.