JP3216272B2 - 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. -In a device composed of a plurality of remote input / output devices that are distributed and arranged to exchange signals with sensors and actuators, a power outage occurring on the remote input / output device side and remote input / output The present invention relates to a decentralized control device capable of reliably transmitting the removal of a device to a control operation device side.

[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. Depending on the nature of the task at hand, a plurality of remote input / output devices are coupled to the control and arithmetic unit via a remote input / output bus so that they can be controlled and controlled.

[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. A cyclic scan transmission is performed for each remote input / output device to maintain (equalize) the contents of the data buffer used by the microprocessor in the device and the input / output data of the remote input / output device. Have been done.

In this type of device, the remote input / output device is often installed separately from the control operation device, and the power is supplied from a power source different from the power supply supplied to the control operation device. The configuration is as follows. Therefore, if a power outage occurs on the remote I / O device side or if the remote I / O device is removed, it is checked whether the remote I / O device operates normally after the power failure is recovered. It is necessary to perform accurate processing such as operation check (inspection) and initial setting for the remote input / output device.

[0005]

In this type of distributed control apparatus, the power failure of the remote input / output device side
For example, because cyclic scan transmission is interrupted,
Although it can be detected on the control arithmetic unit side, there is a problem that it cannot be distinguished from failures in the communication bus, communication interface, and the like. Further, when the power failure occurs for a short time, the cyclic scan transmission is not interrupted, and the power failure cannot be detected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and enables a control operation device to accurately recognize the occurrence of a power failure on the remote input / output device and the fact that the device has been removed. It is an object of the present invention to provide a distributed control device capable of taking appropriate measures after power is restored on the input / output device side.

[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. In a normal state, cyclic scan transmission is performed via a remote input / output bus so that input / output data handled by the control arithmetic unit and input / output data of the remote input / output device are maintained equal. A power failure detection means for detecting a power failure and a momentary power failure of the power supply of the remote input / output device,
If the remote I / O device experiences a power failure or momentary power failure, at least
Power failure detection flag setting means for setting a power failure detection flag indicating the occurrence of a power failure in a communication frame by the first cyclic scan transmission after power recovery , and receiving a power failure confirmation communication sent from the control operation device side, A power failure detection flag setting canceling means for performing response communication with respect to the confirmation communication and instructing to stop setting the power failure occurrence flag in the communication frame is provided, and the control arithmetic unit detects the power failure in the communication frame by the cyclic scan transmission. A power failure detection flag determining means for determining whether or not a flag is set; and, when a power failure detection flag is detected, perform a power failure confirmation communication to the remote input / output device, receive a response to the power failure confirmation communication, A power failure confirmation communication means for determining whether the output device is normal or not. It is.

[0008]

When the power of the remote input / output device is restored from a power failure state, data indicating the occurrence of a power failure (power failure detection flag) is set by a power failure detection data setting means in a communication frame by cyclic scan transmission. The communication frame is transmitted to the control operation device side.

On the control arithmetic unit side, when a power failure detection flag indicating the occurrence of a power failure is detected in the transmitted communication frame, a power failure confirmation communication is performed, and the remote input / output device receives the power failure confirmation communication and responds in response to the power failure confirmation communication. Perform communication. The control arithmetic unit receives the response frame returned from the remote input / output device side, checks whether the remote input / output device after recovery from the power failure is functioning normally, and if it is determined to be normal, detects The detection flag reset communication for canceling the flag setting is performed. When the power outage detection flag is no longer set in the communication frame,
Shift to regular data input / output processing.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration block diagram showing one embodiment of the present invention. In the figure, CNT is a control operation device in charge of control operation, and PI1 , PI2 ... are control operation devices CN.
A plurality of remote input / output devices connected to T via a remote input / output bus BS. Each remote input / output device is arranged in a distributed manner with respect to the control operation device CNT, and is configured to receive an input signal from various sensors installed in a field and output an operation signal to an actuator such as a valve. ing.

In the control arithmetic unit CNT, reference numeral 1 denotes a control arithmetic unit (processor) which is in charge of, for example, PID control arithmetic and sequence control arithmetic, and 2 denotes a power supply circuit in the control arithmetic unit CNT which supplies power to each part. . Reference numeral 3 denotes a non-volatile shared memory, which allows read / write access from the control operation unit 1 and a plurality of remote input / output devices PI transmitted via a remote input / output bus BS.
The input / output data from 1, PI 2,... Is cyclically written in a cycle of oversampling with respect to the calculation cycle of the control calculation unit 1.

4 is a cyclic scan transmission means,
In a normal control operation state, using the remote input / output bus BS, a cyclic operation for maintaining input / output data handled by the control operation unit 1 and input / output data on the remote input / output device PI equal to each other. Perform scan transmission.
5 is a power failure detection flag determining means for determining whether data (power failure detection flag) indicating occurrence of power failure is set in a communication frame by cyclic scan transmission, and 6 is a power failure confirmation communication means, and the power failure detection flag is a power failure detection flag. Determination means 5
If a power failure confirmation communication is performed to the remote input / output device PI, and a response frame from the remote input / output device to the power failure confirmation communication is received, the function of the remote input / output device after the power failure is normal. It is designed to determine whether or not. 7 is a communication interface,
It is configured to perform predetermined communication control for a remote input / output bus BS (including a process field bus which will be standardized in the future).

In the remote input / output device PI, 21 is a communication interface for the remote input / output bus BS, 22 is a power supply circuit for supplying power to each circuit in the remote input / output device, and a power supply circuit in the control arithmetic unit CNT. 2 has a different configuration. Here, it is assumed that this power supply circuit is located in the remote input / output device, but this power supply circuit is installed outside, for example, when power is supplied through a connector on the backboard. A configuration may be used. 23 is a power failure detection means for detecting a power failure of the power supply circuit 22 and removal of the device from the backboard.
A known circuit that monitors a decrease in the supply voltage value from the power supply circuit 22 or the like can be used. When a power failure or removal of the device is detected, the fact is stored in a nonvolatile memory or the like.

Reference numeral 24 denotes a cyclic scan transmission unit for performing cyclic scan transmission with the cyclic scan transmission unit 4 on the control arithmetic unit CNT side. Reference numeral 25 denotes a power failure detection flag setting unit. If a power failure has been detected, a power failure detection flag indicating that a power failure has occurred is set in the communication frame by the cyclic scan transmission means 24. Reference numeral 26 denotes a power failure detection flag setting canceling means, which performs response communication in response to the power failure confirmation communication sent from the control operation device CNT side, and determines whether the function of the remote input / output device after the power failure recovery is normal on the control operation device side. In response to the detection flag reset communication (this communication is also performed as one of the power failure confirmation communication) transmitted when it is determined that there is, the power failure detection flag setting in the communication frame is stopped. , To the power failure detection data setting means 25.

Reference numeral 27 denotes an input / output circuit which handles data from a sensor and data output to an operation terminal such as a valve. In the control arithmetic unit CNT and the remote input / output unit PI, each of the cyclic scan transmission units 4 and 24, the power failure detection flag determination unit 5, the power failure confirmation communication unit 6, the power failure detection data setting unit 25, and the data setting cancellation unit 26 Are realized by a transmission control microprocessor. Each of the communication interfaces 7 and 21 has a configuration in which input / output data is normally transmitted as a bit-serial signal to the remote input / output bus BS and is transmitted in a predetermined format, or these signals are received. ing.

The operation of the apparatus having the above configuration will be described below. (Operation in Normal Control Operation State) In the control arithmetic unit CNT, the cyclic scan transmission unit 4 maintains the input / output data handled by the control arithmetic unit 1 and the input / output data of the remote input / output unit PI equal. For this purpose, the cyclic scan transmission is performed in cooperation with the cyclic scan transmission means 24 of the remote input / output device PI. This cyclic scan transmission is cyclically performed at a cycle of oversampling with respect to the control calculation cycle of the control calculation unit 1, and a plurality of remote input / output devices P
Input / output data from I 1, PI 2... Are written, and the contents are updated.

The control operation unit 1 reads out input / output data written in the shared memory 3 at a control operation cycle, and performs a predetermined control operation using these data.
The calculation result is written to the shared memory 3. Shared memory 3
Is sent to the plurality of remote input / output devices PI1 , PI2, ... And is reflected in the operation of the actuator connected to the remote input / output devices PI1 , PI2,.

By such an operation, for example, a control operation in which the opening / closing degree of a valve (valve) is controlled following the calculation result of the control calculation unit 1 is performed. It is to be noted that which device of the plurality of remote input / output devices PI 1, PI 2... Corresponds to which address position of the shared memory 3 and what kind of data transmission is to be performed at the time of starting the operation of the device. It is assumed that the setting is made for each remote input / output device.
(Operation when power is restored after a power failure or removal of a remote input / output device) FIG.
Is a flowchart showing an operation on the remote input / output device PI side, and FIG. 3 is a flowchart showing an operation on the control arithmetic unit CNT side.

In the remote input / output device PI, when the power failure detection means 23 detects a voltage drop from the power supply circuit 22 or the removal of the device from the backboard, the power failure detection means 23 realizes each means in the remote input / output device PI. A reset signal is sent to the microprocessor of (1) to reset the microprocessor (steps 1 and 2). Upon recovery from the power failure or when the device is mounted again on the backboard, the power failure detection means 23 detects the recovery from the power failure and outputs a reset release signal to the microprocessor (step 3,
4). When the microprocessor in the remote input / output device PI is activated, the cyclic scan transmission by the cyclic scan transmission means 24 is restarted.

Here, the power failure detection flag setting means 25
Data (power failure detection flag) indicating that a power failure has occurred or the device has been removed from the backboard is set in a communication frame output from the cyclic scan transmission means 24 (step 5). FIG. 4 is a configuration diagram showing an example of a communication frame (communication packet) output onto the remote input / output bus BS by the cyclic scan transmission means 24.

At the beginning of the communication frame, there is a preamble portion, followed by a destination address ADR and a source address (address representative of the remote input / output device PI) SA.
D, a power failure detection flag FG indicating that a power failure has occurred or the device has been removed from the backboard, data DA sent from the remote input / output device, and finally parity PY. If there is no power failure or the fact that the device has been removed from the backboard, the power failure detection flag F
G has been reset.

In the control arithmetic unit CNT, the cyclic scan transmission means 4 receives the communication frame having such a configuration and extracts necessary data (step 21).
Further, the power failure detection flag determination means 5 includes, in the communication frame,
It is determined whether there is a power failure detection flag (step 22). Here, when the power failure detection flag is detected, the fact that a power failure has occurred on the remote input / output device side is reported to a higher-level computer (not shown, but an operator functioning as a man-machine interface existing on the higher-level side of the control operation device) Station, etc.) (step 24), and the power failure confirmation communication means 6 performs a power failure confirmation communication to the remote input / output device PI (step 25).

When the remote input / output device PI receives this power failure confirmation communication, the data setting canceling means 26
A response communication (transmission of a response frame) to the power failure confirmation communication is performed (step 7). In this response communication, for example, database information (sum check data, data length, and the like) of the remote input / output device is mounted in a response frame and sent from the remote input / output device PI. The power failure detection flag is not set in this response frame.
In step 23, the reception of the response frame is detected.

When the control arithmetic unit CNT receives this response frame, it determines from the database information whether the database of the remote input / output unit PI after the recovery from the power failure has disappeared or the function is normal (step 2).
6). If it is determined that the remote input / output device is normal, detection flag reset communication for resetting the power failure detection flag is performed (step 27).

The power failure detection flag setting canceling means 26 of the remote input / output device PI receives this detection flag reset communication so as to stop (reset) the power failure detection flag setting operation by the power failure detection flag setting means 25 thereafter. Instruct (step 8). Subsequent operations perform a regular input / output process while monitoring the occurrence of a power failure (steps 9 and 10).

On the other hand, in the control arithmetic unit CNT, if it is determined in step 26 that the operation of the remote input / output device PI is not normal, the inspection communication process is performed on the remote input / output device (step 28). ). The inspection communication processing is configured by a program for performing inspection and initial processing after recovery from a power failure, and confirms whether transmission of a communication frame can be normally performed between the control arithmetic device and the remote input / output device, Includes necessary database download processing. After performing such inspection and initial processing on the remote input / output device, power outage confirmation communication is again performed with the remote input / output device PI (step 29).
Wait for a response frame from the remote input / output device.

If the operation / function of the remote input / output device is determined to be normal and the power failure detection flag disappears from the communication frame by the cyclic scan transmission means based on the detection flag reset communication performed in step 27, In step 30, it is determined that there is no power failure detection flag, and the process shifts to normal input / output data processing (step 30).

After performing the test communication process on the remote input / output device PI in step 28, if the remote input / output device is not normal as determined in step 26, the test communication process is executed in steps 28 and 29. And the power failure confirmation communication will be performed repeatedly. Therefore, the number of repetitions is set in advance, and when the set number of times is reached, the remote input / output device is determined to be abnormal and the subsequent processing is terminated.

[0029]

As described in detail above, the present invention provides
When a power failure occurs or the device is removed on the remote I / O device side, the information is set in a communication frame by cyclic scan transmission after power is restored, and is transmitted. In the meantime, even if there are several media, the fact that a power failure has occurred can be reliably transmitted to the control operation device side, and the remote input / output device may malfunction due to a power failure or removal from the device. In such a case, it is possible to take appropriate measures. Further, the distributed control device of the present invention includes a control arithmetic device and
If a communication error occurs with the remote I / O device,
This is a communication error due to an error that occurred on the communication path
Or a communication error due to a power failure on the remote I / O device side.
The power from the remote I / O device when power is restored
・ First communication data transmitted by scan transmission
Can be determined. In addition, remote entry and exit
Power failure due to communication data transmitted immediately after the power
Detection is possible, so cyclic scan cycle
Power failure detection even for momentary power failures occurring between
It becomes possible.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the remote input / output device PI.

FIG. 3 is a flowchart showing the operation of the control arithmetic unit CNT.

FIG. 4 is a configuration diagram illustrating an example of a communication frame (communication packet) output on a remote input / output bus BS by a cyclic scan transmission unit 24;

[Explanation of symbols]

 CNT Control operation device PO1, PO2 ... Multiple remote input / output devices BS Remote input / output bus 1 Control operation unit (processor) 2 Power supply circuit 3 Non-volatile shared memory 4 Cyclic scan transmission means 5 Power failure detection flag determination means 6 Power failure confirmation Communication means 7, 21 Communication interface 22 Power supply circuit 23 Power failure detection means 24 Cyclic scan transmission means 25 Power failure detection flag setting means 26 Power failure detection flag setting release means 27 I / O circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G05B 11/36 G05B 9/02 H04Q 9/00-9/06

Claims (1)

(57) [Claims] The present invention 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 distributed control device for performing cyclic scan transmission for maintaining the input / output data handled by the control arithmetic unit and the input / output data of the remote input / output device equally, comprising: A power failure detection means for detecting a power failure and a momentary power failure of a device, and at least a power failure or a momentary failure of a remote input / output device
Power failure detection flag setting means for setting a power failure detection flag indicating the occurrence of a power failure in a communication frame by the first cyclic scan transmission after power recovery , and receiving a power failure confirmation communication sent from the control operation device side, A power failure detection flag setting canceling means for performing response communication with respect to the confirmation communication and instructing to stop setting the power failure occurrence flag in the communication frame is provided, and the control arithmetic unit detects the power failure in the communication frame by the cyclic scan transmission. A power failure detection flag determining means for determining whether a flag is set; and, if a power failure detection flag is detected, perform power failure confirmation communication to the remote input / output device side, receive a response to the power failure confirmation communication, and receive a remote power-on confirmation signal. And a power failure confirmation communication means for determining whether or not the output device is normal. Location.