JP2993349B2 - Distributed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed control device for controlling a process quantity such as a temperature and a pressure, and more particularly, to a control operation device for performing various control operations and a control operation device separated therefrom. A device composed of a plurality of remote input / output devices that are arranged in a distributed manner and transmit and receive signals to / from sensors and actuators. And a distributed control device.

[0002]

2. Description of the Related Art A distributed control device is configured to input a large number of signals from a process to be controlled and to output operation signals to a large number of control terminals, and to comprehensively monitor the entire controlled object. A plurality of remote input / output devices are coupled to the control arithmetic unit so as to be able to control and control the job.

[0003] Here, a shared memory is provided between the control arithmetic device and the remote input / output device, which allows read / write access from both of them, and the control arithmetic device is connected via a remote input / output bus. In order to maintain (equalize) the contents of the data buffer used by the internal processor and the input / output data on the remote input / output device side equally, cyclic scan transmission is performed for each remote input / output device. ing.

[0004] In this type of conventional device, it is assumed that the control operation device side and the remote input / output device side are operated integrally by being supplied with power from the same power supply system. There was not much need to consider the case in which the operation became abnormal alone.

[0005]

However, when the scale of the process becomes large, the control operation device and each remote input / output device are arranged at different places, respectively, and power is supplied from a power supply of another system. Then, the remote input / output device is out of power, restored, broken down, or removed due to a periodic inspection of the plant at a timing independent of the control arithmetic device.

[0006] Accordingly, it is necessary for the control arithmetic unit to recognize the operating state of the remote input / output device for each remote input / output device, and to take appropriate measures for it. The present invention has been made in view of such circumstances, and the control operation device side determines whether the operation of each remote input / output device is normal or abnormal (including a case where the operation is stopped due to a power failure or the like). It is an object of the present invention to provide a decentralized control device capable of recognizing and promptly taking appropriate action when any abnormality occurs.

[0007]

SUMMARY OF THE INVENTION The present invention, which achieves the above object, comprises a control operation device in charge of control operation and a remote input / output device connected to the control operation device via a remote input / output bus. A remote control I / O diagnostic means configured to periodically communicate with a remote I / O device in said control arithmetic device to diagnose whether or not the operation of said remote I / O device is normal. A node status storage means for storing a diagnosis result by the remote I / O diagnosis means; a common switch capable of holding at least two states; and a result of periodically reading the diagnosis result from the node status storage means. Node state notification means for reflecting the state of the common switch as a single input, and according to the state of the common switch. A distributed control system which is characterized by providing a sequence control means for performing constant-sequence process.

[0008]

When each remote input / output device and the control operation device are operated by supplying power from different power supplies, power failure and power recovery occur at independent timings. When any abnormality occurs on the remote input / output device side, the remote I / O diagnostic means on the control operation device side detects it, and the information is written into the node status storage means.

The node status notifying means periodically reads out the diagnosis result from the node status storage means and reflects the result on the state of the common switch. As the common switch and the sequence control means, those prepared in advance as functions of the control arithmetic device are used, and the sequence control means captures the operation state of the remote input / output device via the common switch.

Thus, the control arithmetic unit can cope with a process when the remote input / output device becomes abnormal by a general method such as a sequence table.

[0011]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration conceptual diagram showing an example of a distributed control device to which the present invention is applied. In the figure, FC is a control operation device in charge of control operation, OP is a monitoring device (operator station) in charge of operation and monitoring of a plant, and these are connected by a communication line VN.
PO1, PO2,... Are connected to the control operation unit FC by the remote input / output bus BS and the node interfaces NIF1, NIF.
Are a plurality of remote input / output devices connected via F2.

Each of the remote input / output devices PO1, PO2,.
Are arranged in a distributed manner with respect to the control operation device FC, and are configured so that an input signal is applied from various sensors installed in the field and an operation signal is output to an actuator such as a valve. Each remote input / output device includes a plurality of units U1, U2, U3,... Configured to collectively handle a plurality of remote input / output signals.

Further, these units U1, U2...
A function to convert the signal from the process into a digital data signal form that can be handled by the control operation unit FC, a function to convert the signal from the control operation unit to an analog signal or contact signal that can be handled by a valve, etc. It is composed of a plurality of printed board cards on which electronic circuits for realizing the functions are mounted.

The node interfaces IF1, IF2,...
Is a control arithmetic unit FC via a remote input / output bus BS.
It has a function of communicating with the remote controller, and data can be transmitted between each remote input / output device and the control processor FC according to a predetermined communication protocol. In this example, the communication line VN and the remote input / output bus BS have a duplex configuration, but may have a single configuration.

FIG. 2 is a functional block diagram showing an embodiment of the present invention. In the control arithmetic unit FC, CP is a processor unit that performs control arithmetic and the like, CM is a communication unit that functions as an interface to the remote input / output bus BS, and these processor units and the communication unit are connected to the internal bus EB.
Connected by S. A remote I / O diagnostic unit 11 that periodically communicates with the remote input / output device and diagnoses whether the operation of the remote input / output device is normal is provided in the communication unit CM.
And a node status storage unit 12 for storing a diagnosis result of the remote I / O diagnosis unit 11.

A common switch 2 capable of holding at least two states is provided in the processor unit CP.
1, a node status notifying means 22 for periodically reading out the diagnosis result of the node status storage means 12 and reflecting the result on the state of the common switch, and taking in the state of the common switch as one input, and There is provided a sequence control means 23 for performing a predetermined sequence process in response to this. Here, the common switch 21
Are provided in a number corresponding to the number of remote input / output devices connected to the remote input / output bus BS.

A large number of common switches 21, sequence control means 23, and the like are prepared in advance in the control operation device FC, and originally perform PID control operation, sequence control operation, and the like on signals from the process. One of the features of the present invention is that these elements are used for monitoring the operation state of the remote input / output device.

In each of the remote input / output devices PO1, PO2,..., The node interface NIF is connected to the communication unit C
M. Remote input / output devices PO1, PO
2 are connected to the operation terminals of sensors, valves, etc., and each input / output signal (analog input / output signal, digital input / output signal)
It has a signal processing function to handle signals, collects signals from sensors, and outputs operation signals to valves and the like. Further, the node interface NIF realizes communication by cyclic scan transmission with the control arithmetic device FC.

FIG. 3 is a conceptual diagram showing an example of a communication frame in which a node status transmitted from the remote input / output device is entered on the remote input / output bus BS. This communication frame is transmitted to the remote I / O of the control operation device FC.
PRA is a preamble portion provided at the beginning of the frame, STF is a start flag indicating the beginning of the frame, ADR is a receiving address, SA
D is the address of the transmitting node, and NOIF is information indicating the state of the transmitting node. This information includes node statuses F1 and F2 indicating abnormal operation and normal operation of the node (in this example, the node has a duplex configuration, and the states of those nodes are indicated by F1 and F2). FCS is a frame check sequence, and EDF is an end flag.

The operation of the apparatus having the above-described configuration will be described below. Remote I / O diagnostic means 11 in control arithmetic unit FC
Transmits a diagnostic command to the remote input / output devices PO1, PO2,... Connected to the remote input / output bus BS at regular intervals, and collects responses from the remote input / output devices. At this time, for example, when the node interface unit INF of the remote input / output device and the remote input / output bus BS have a duplex configuration, a diagnostic command is transmitted for each bus and the response is collected.

The remote I / O diagnostic means 11 extracts the node statuses F1 and F2 from the communication frame transmitted as a response. Storage means 1
Data (contents) F of the corresponding node (corresponding address) 2
Bits 1 and 2 are set to "1". If normality is detected twice consecutively, the F1 and F2 bits are set to “0”.

FIG. 4 is a conceptual diagram of the configuration of the node status storage means 12. Information on each remote input / output device (node) is written in address order. Each of these pieces of information is designated by an address (node), read out by the node state notifying means 22 at a fixed period, and read by the corresponding common switch 2.
1 reflects the contents. That is, if both bits F1 and F2 of a certain node are “1” indicating an abnormality, the state of the corresponding common switch is set to “1”. If either bit of F1 or F2 is “0” indicating normality, the state of the corresponding common switch is set to “0”.

The sequence control means 23 receives a state signal from the corresponding common switch 21. When the state signal changes, the sequence control means 23 notifies the sequence processing in accordance therewith, for example, that the remote input / output device has become abnormal. Processing such as driving the annunciator on or operating the backup device is performed. The type of processing to be performed by the sequence control means 23 is determined by a sequence table prepared in the sequence control means (a table in which the relationship between the condition input signal and the operation output signal is described in a Yes / No pattern table). ), The user can describe desired items to perform desired processing. That is, for example, a common switch is described in a condition input signal column, and an annunciator or a
Describe the backup device, and the common switch is, for example,
It is sufficient to describe that the annunciator and the backup device are turned on when the status changes from “0” to “1”.

In the above description, the setting of the processing of the sequence control means has been described on the assumption that a sequence table is used. Which is described using the above).

[0025]

As described above in detail, according to the present invention, it is possible to monitor the operation state of a remote input / output device for each remote input / output device and to perform processing when an abnormality occurs. Can be set to a form most suitable for each user by a general method by setting the operation of the sequence control means by a user (for example, by describing a sequence table). Therefore, a user-friendly and highly flexible distributed control device can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration conceptual diagram of a distributed control device to which the present invention is applied.

FIG. 2 is a functional block diagram showing one embodiment of the present invention.

FIG. 3 is a conceptual diagram illustrating an example of a communication frame in which a node status transmitted from a remote input / output device is entered on a remote input / output bus BS.

FIG. 4 is a conceptual diagram of a configuration of a node status storage unit.

[Explanation of symbols]

 OP monitoring device FC control operation device NIF node interface PO1, PO2, ... remote input / output device BS remote input / output bus CP processor unit CM communication unit 11 remote I / O diagnostic unit 12 node status storage unit 21 common switch 22 node status notification unit 23 Sequence control means

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) G05B 23/02 302 G05B 23/02 G05B 19/048 H04Q 11/00

Claims (1)

(57) [Claims] 1. A distributed control device comprising: a control operation device in charge of a control operation; and a remote input / output device connected to the control operation device via a remote input / output bus. A remote I / O that periodically communicates with the remote input / output device and diagnoses whether or not the operation of the remote input / output device is normal
Diagnosis means; node status storage means for storing a diagnosis result of the remote I / O diagnosis means; a common switch capable of holding at least two states; and periodic reading of the diagnosis results from the node status storage means Node state notifying means for reflecting the result on the state of the common switch, and sequence control means for taking in the state of the common switch as one input and performing predetermined sequence processing according to the state of the common switch are provided. Distributed control device.