JPH02158806A - Control processing system for programmable controller for plant use - Google Patents

Abstract

PURPOSE:To safely restart control by preventing a control signal from being outputted immediately after restoration from a troubled state. CONSTITUTION:When a programmable controller turns into the troubled state, a sequence control status is switched automatically from an ON-state to an OFF-state, and the output of the control signal to an apparatus to be controlled is inhibited. Thus, since the control signal is not outputted from the programmable controller to the apparatus to be controlled until the sequence control status is switched from the OFF-state to the ON-state even though the programmable controller is restored from the troubled state, the apparatus to be controlled never starts operation suddenly at the time to the start after the restoration of the programmable controller. Thus, the control can be restarted safely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control processing method for a programmable controller used as a control device for controlling auxiliary equipment, valves, etc. in various plants.

[Prior Art] Fig. 3 is a flowchart for explaining the control processing method of a conventional programmable controller for plants.As shown in Fig. 3, when the control processing of the programmable controller is started, After performing initialization processing when raising (
Step A1).

Input processing is performed to take in external signals necessary for sequence control calculations from the input section (step A, 2).

Then, sequence calculation is performed in the control calculation section (
Step A3): Output the calculated control signal to controlled equipment (auxiliary machines, valves, etc.) in the plant via the output section. Output processing is performed (step A4). Thereafter, the operations of steps A2 to A4 are repeated.

[Problems to be Solved by the Invention] Since the control processing method of the conventional programmable controller for plants is performed according to the control flow as described above, when the programmable controller is started up after recovering from a failure state such as a power cut, This results in the control state being reached and the control calculation result based on the input signal being output. Therefore.

In this case, the control signal is output only by the operator's restoration operation of the programmable controller, and there is a risk that the auxiliary equipment may suddenly operate.

This invention was made in order to solve the above-mentioned problems, and is a programmable controller for plants that does not output control signals immediately after recovery from a failure state, so that control can be safely resumed. The purpose is to obtain a control processing method.

[Means for Solving the Problems] A control processing method for a programmable controller for a plant according to the present invention automatically switches the sequence control status from the on state to the off state when the programmable controller becomes in a failure state, and the sequence control status is automatically switched from the on state to the off state. Unless the status is switched from off to on, output of control signals from the programmable controller to the controlled device is prohibited.

[Function] In the control processing method of the programmable controller for a plant according to the present invention, even if the programmable controller recovers from a failure state, the control processing method from the programmable controller to the controlled equipment remains unchanged until the sequence control status is switched from the off state to the on state. Since no control signal is output, the controlled device will not suddenly start operating when the programmable controller is started up after recovery.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

First, the configuration of a plant programmable controller to which the method of this embodiment is applied will be explained with reference to FIG.
In FIG. 2, 1 is an input unit that inputs the status of input equipment 1a in the plant, and 2 is an arithmetic unit that performs logical operations on the input status and internal information of the plant that are input through the input unit 1. The unit 2 automatically switches the sequence control status in the display/operation unit 4, which will be described later, from the on state to the off state when the programmable controller itself becomes in a failure state.

Further, 3 is a storage unit that stores the results processed by the calculation unit 2, and 4 is an operation display unit that sends various commands to the calculation unit 2 and displays the status of the calculation unit 2, and displays the sequence control status. A sequence control status switch is provided that stores and displays the on/off state using hardware.

The calculation unit 2 prohibits the output unit 5 from outputting control signals to the various controlled devices 6 unless the sequence control status switch in the display operation unit 4 is switched from the off state to the on state. It has become.

Using the programmable controller configured as described above, the system of this embodiment is implemented as shown in FIG. first,
As in the past, when control processing of the programmable controller is started, initialization processing is performed when the programmable controller is started up (step S1).
), an input process is carried out to take in external signals necessary for the sequence control calculation from the input unit 1 (step S2), and a sequence calculation is performed in the calculation unit 2 (step S3).

At this time, the calculation unit 2 determines whether the sequence control status in the display operation unit 4 is on (step S4). The sequence control status changes when the programmable controller goes into a fault state.
It is automatically switched from the on state to the off state, and the off state is maintained unless the switch is operated by the operator.

Therefore, if the sequence control status is on, the output unit 5 outputs a control signal to the controlled device 6 such as an auxiliary machine and outputs various information (step S5), while the sequence control status is off. If it is, the control signal is prohibited from being output to the controlled device 6 such as an auxiliary device, and only various information is output (step S6).

As described above, according to the method of this embodiment, when the programmable controller moves from the failure state to the control state,
Even if the programmable controller recovers from a failure state, no control signal is output from the programmable controller to the controlled device 6 until the sequence control status is switched from the OFF state to the ON state by the operator. Blocked. Then, when the operator operates the switch on the operation display section 4 to switch the sequence control status from the OFF state to the ON state, output of the control signal to the controlled device 6 is restarted.

Therefore, when the programmable controller is started up after recovery, the controlled equipment 6 will not suddenly start operating, and the operator can extremely safely program the Control by the controller can be resumed.

In the above embodiment, the sequence control status is switched from the off state to the on state by the operator's operation, but it may be automatically switched based on external information input from the input unit 1. .

[Effects of the Invention] As described above, according to the present invention, even if the programmable controller recovers from a failure state, the programmable controller does not control the controlled equipment until the sequence control status changes from the OFF state to the ON state. Since the configuration is configured to prohibit signal output, the controlled device does not suddenly start operating immediately after the programmable controller is restored, and control can be resumed extremely safely after the operating state of the controlled device is confirmed.

[Brief explanation of the drawing]

FIG. 1 is a flowchart for explaining the control processing method of a programmable controller for a plant according to an embodiment of the present invention, FIG. 2 is a block diagram showing a programmable controller to which the method of the above embodiment is applied, and FIG. It is a flowchart for explaining the control processing method of the conventional programmable controller for plants. In the figure, 1.-manpower section, 2.. calculation section, 3..
Storage unit, 4-Display operation unit, 5-Output unit, 6... Controlled equipment. Figure 1

Claims (1)

[Claims] In a control processing method for a programmable controller that controls controlled equipment in a plant, when the programmable controller enters a failure state, the sequence control status is automatically switched from an on state to an off state, and the sequence control status is changed from an off state to an on state. 1. A control processing method for a programmable controller for a plant, characterized in that output of a control signal from the programmable controller to the controlled device is prohibited unless the state is switched.