JPS58121402A - Sequence controller - Google Patents

Abstract

PURPOSE:To perform sequence control with high safety by preventing erroneous output of a plant when a sequence controller becomes abnormal and recovers. CONSTITUTION:An external locking circuit 20, and an external lock contact judging circuit 3C and a system program ending position detecting part 3D in an arithmetic control part 3 are provided. This external locking circuit 20 consists of a lock relay 22 connected to a reset switch 21 and a fault detection contact 13 in series, and its (a) contacts 22A and 22B and (b) contact 22C. Therefore, a system program part 3A normally performs prescribed arithmetic according to an input from an input part 4 to bring a control device 9 under ON-OFF control through an output part 5 on the basis of the arithmetic result. Further, the lock relay 22 forms a self-holding circuit through the contact 22A in an ON state.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION The present invention relates to an L&S sequence control device using a sequence controller.

TECHNICAL BACKGROUND OF THE INVENTION In general, sequence control devices that sequentially operate pumps, solenoid valves, and electric motorized plant equipment have recently been
Sequence controllers based on Micro Zoro Nanatsusa have come into use.

feed! The figure shows an example of this, in which a sequence controller 1 has a power supply section 2. Arithmetic control section 3° input section 4. It has 115 outputs, and its arithmetic control section is composed of three microprocessors. In addition, the arithmetic control unit 3 includes a logic loader 6III as a maintenance device, which has a sequence/monitor function, etc., although it is not directly related to the present application.
is connected.

Seven external circuits allow plant status and operation switches.

The condition contacts 8 such as 8 are connected to the input section 4 of the sequence controller, and the control devices such as timers and auxiliary relays that drive plant equipment are connected to the output section 8 of the sequence controller.
It is connected to the.

Furthermore, the arithmetic control section 3. Input section 4. Power supply section 2 to output section 5 etc.
Sequence controller control power supply for supplying necessary power via 10. The sequence control device includes an input control power source 11 and an output control power source 12 that supply necessary power to the conditional contacts 8 and the control equipment 9.

With such a configuration, sequence control is performed by the arithmetic control section 3 receiving plant input conditions from the condition contact 8 through the input section 4, storing and arithmetic processing based on the plant input conditions according to a predetermined system program, The result is outputted to the control device 9 via the output section 5 to operate the plant equipment.

By the way, when a software or software abnormality or an abnormality related to the control power supply occurs in the sequence controller 1 or its external circuit 7 of such a sequence control device, conventionally, as a countermeasure, the sequence controller l 5 has a self-diagnosis function, and when these abnormalities are detected, an output OFF command is issued from the arithmetic control section 3, all signals held in the output register of the output section 5 are reset, and the printing equipment is turned off. At the same time, an abnormality alarm signal is outputted via the abnormality detection contact 13 to notify the operator. Furthermore, after the abnormal condition is removed, the sequence controller lti automatically reads the input and starts calculation,
The system program was executed and output was performed according to the calculation results.

Problem with Background Collision However, in the conventional configuration described above, it is impossible to tell whether the abnormality has been completely repaired until the system is restarted.

At this time, the plant system program operates according to the conditions input to the sequence controller 1, but if the abnormality has not been completely repaired, erroneous outputs and abnormal calculation operations are performed. Furthermore, even if the abnormality is corrected, the system program may start midway, causing unexpected plant equipment to suddenly operate, causing unexpected situations, and other problems resulting in a lack of safety as a control device.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a sequence control device that can prevent erroneous outputs during abnormality and recovery of the sequence control device and safely resume operation.

SUMMARY OF THE INVENTION In order to achieve this object, the present invention forcibly turns off the output from the sequence controller output section independently of the output OFF command from the sequence controller calculation control section when the sequence control device is abnormal. OFF), and at the time of restart, the lock circuit is operated to prevent the lock from being released until the reset switch provided in the lock circuit is operated.
The input signal is inputted as an input signal to a sequence controller, and when the system program is in the program state, the system program of the plant is overridden, the system program of the plant is not executed, and the reset switch is operated after the abnormality is recovered. By doing so, the pino parable is resolved and the system and programs are executed and output normally.

Examples of the invention Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 2 is a block diagram of a sequence control device according to an embodiment of the present invention. In the figure, the symbols -1- as in FIG. 1 indicate the same or corresponding parts.

In the configuration shown in the figure, the arithmetic unit 3 includes a system program unit 3M and a sequence controller self-diagnosis unit 3B that perform calculations to advance the plant state to the next status in response to input from the input unit 4. dots and dotted lines in which the output section 5 is composed of an output register 5, an output transistor 5B, and a relay 5C.Although this is the same as in the conventional case, in the case of this embodiment, in addition to the above structure, an external lock circuit is also provided. 20
The present invention is characterized in that an external port, a contact point determination section 3C, and a system program completion position detection sBD are provided in the arithmetic and control section 3.

A lock relay 22 connected in series to this external port, circuit 20, reset switch 21, and abnormality detection contact 13;
It is composed of J& contacts 22A, 22B and b contact 22C.

The sequence control device of this embodiment is configured as described above, and in normal operation, the system ZOLOGRAM 5 section 3 performs a predetermined calculation according to the input from the input section 4, and the result is outputted via the output section 5. Turn on the control device 9.

It is controlled to be OFF. When the relay 22 is turned on, a self-holding circuit is formed by the contact 22A.

If an abnormality occurs in the sequence controller in this state, the self-diagnosis section 3B generates an abnormality signal and turns off the output of the output register 5A and the abnormality detection contact 13. When the abnormality detection contact 13 is turned OFF, the self-holding circuit of the relay 22 is released and the contact 22B is turned OFF. As a result, the relay 50 turns OFF, and the output section 5F! , completely OF
It becomes F lock state.

Further, the arithmetic control section 3 stops its operation upon detecting an abnormality in the self-diagnosis section 3B.

If the cause of the abnormality in the sequence controller is removed and the sequence controller returns to a normal state, the arithmetic and control unit 3 will start operating again. That is, the abnormal signal from the self-diagnosis section 3B disappears,
The output OFF command of the output register 5A is canceled and the abnormality detection contact 13 is turned ON. However, at this time, it will not turn on unless lock relay 22 beam +, tosui, and chi 21 are turned on. Therefore, contact 22Bd is still OFF.
The output OFF state is maintained, and the output OFF state is maintained. This prevents erroneous output from the arithmetic and control section 3 to the control device 9, and ensures safety as a control device.

On the other hand, when the sequence controller returns to normal, the arithmetic control unit 3 starts operating, but at this time, an ON signal of the contact 220 is input from the external lock circuit 20 to the arithmetic control unit 3 via the input unit 4. From the external port K, the contact determination section 3C presses the system program section 3 and proceeds with the calculation to the system program completion position (END).Next, the operator confirms that there is no abnormality. If you confirm this and press the reset switch 21, the lock relay 22 will turn on and hold itself again. As a result, the contact 22B turns ON,
The OFF lock of the output unit 5 is released, the contact 22C becomes 0FFL, and the output of the system program @3 is output to the output unit 5 via the self-judgment unit 3B. At this time, since the system ZOLOGRAM 3 executes the program from the first step, the controller s19 is assumed to be operated normally based on the result calculated according to the system program (by the plant's human power after the abnormality recovery). become.

That is, only the output circuit is turned off by the external lock circuit 20.
If you just do this, the system program will be executed according to the input conditions of the Hiro plant after the sequence controller returns normally, and the system program will progress in sequence, and when you press the reset switch 21, the sequence will have already progressed and you will be in the t5 mourning state. There is a risk that the output unit 5 will be activated and the control equipment 9 will be driven, causing plant abnormalities such as plant trips, but according to this embodiment, it is possible to reliably prevent erroneous outputs including these stutterings. Effects As described above, according to the present invention, it is possible to obtain an extremely safe sequence control device that can prevent erroneous outputs to the plant when the sequence control device is in an abnormal state and at the time of recovery.

[Brief explanation of drawings]

1 is a block diagram of a general sequence control device, and FIG. 2 is a block diagram of a sequence control device according to an embodiment of the present invention. 1... Sequence controller, 2... Electric 1ll
s, 3...Arithmetic control unit, 3A...System program unit, 3T...Self judgment unit, 3C...External lock contact judgment unit, 3D...System program completion position detection unit, 4...・Input section, 5... Output section % 5A... Output register, 5B... Output transistor, 5C... Relay, 6... Logic low end, 7... External circuit, 8
...Condition contact, 9...Control equipment, 10...Sequence controller control power W, 11...Input control power supply,
12... Output control power supply, 13... Abnormality detection contact, 2
0--external c1-switch circuit, 21--seven switch, 22--lock relay, 22m.

Claims (1)

[Scope of Claims] An input unit that captures input conditions of the plant, a calculation unit that performs sequence calculations according to a predetermined plant system zologram based on the brand input conditions, and various controls of the plant based on outputs from the calculation unit. In a sequence control device equipped with an output section for driving a device, when the sequence control device becomes abnormal, the output section is locked and the output section is locked, and a output section is outputted to the calculation section. death. When normality has been restored, an external lock circuit is provided which shifts to the second state by pressing the reset button and releases the opening of the output section and stops outputting the first state signal. KFi in the arithmetic unit is configured to check the input of the first state signal, and a determining unit is provided to advance the plant system zologram to the completion position when the external port circuit is in the first state, and the external lock circuit When transitions to the 112 state, the calculation unit executes the plant system 7#a program from the beginning, outputs the calculation result to the output unit, and outputs the calculation result to the controller that drives each of the controllers. A sequence control device characterized by: