JPH0981201A - Fieldbus control system - Google Patents

Abstract

(57) Abstract: An object of the present invention is to maintain a situation in which basic control can be continued and plant operation can be continued even if a fieldbus is disconnected. SOLUTION: A field bus 13 which connects a sensor section 10-1, an operation end section 12-1, and a control apparatus section 11-1.
Is disconnected, the target value Q sent from the control device 2-1 is held by the target value holding unit 21, and the held target signal Q is passed to the simple control unit 22 and output by the sensor unit 10-1. The operation signal Ma is output to the operation end 3-1 so that the detection signal P that becomes the target signal Q becomes
Continue with simple control.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to steel, petrochemical,
The present invention relates to a fieldbus type control system applied to manufacturing processes such as electric power, pulp, food, and pharmaceutical industries.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a process control device applied to a manufacturing process in such a steel industry. This process control device controls sensors (detection ends) 1-1 to 1-n for detecting a process amount and detection signals (process signals) output from these sensors 1-1 to 1-n to target signals. For outputting operation signals for
n, and operating ends 3-1 to 3-n such as valves for actually operating the process by receiving the operating signals output from these control devices 2-1 to 2-n.

Of these, the sensors 1-1 to 1-n and the operating terminals 3-1 to 3-n are installed in the field, and control devices 2-1 to 2-1 are installed.
-N is installed in the central control room. This process control device includes these sensors 1-1 to 1-n and respective operation terminals 3-.
The control loops are formed by connecting the control devices 2-1 to 2-n to the control devices 2-1 to 2-n in a one-to-one manner.

For example, the sensor 1-1, the operating end 3-1, and the control device 2-1 are connected to form one control loop,
Moreover, a cable is connected between the site of the control loop and the central control room. Further, the sensor 1-2, the operating end 3-2 and the control device 2-2 are connected to form one control loop, and the site of the control loop and the central control room are connected by a cable.

FIG. 4 is a block diagram of one such control loop. The detection signal P output from the sensor 1-1 is input to the control device (station) 2-1.

The control unit 2-1 is connected to the arithmetic unit 4, and various signals 5 are input through the arithmetic unit 4 and the target signal (set value) Q obtained by the arithmetic unit 4 is input, and the sensor 1 is connected. A control operation such that the detection signal P from -1 becomes the target signal Q, for example, PID operation is executed, and the operation signal M as the operation result is output to the operation terminal 3-1.

In such a process control device, a cable is provided between the site and the central control room on a one-to-one basis for each control loop.
Since it is connected with, this cable and control device 2-1 ~
2-n I / O device and cable laying work requires cost.

In order to reduce such cost, as shown in FIG. 5, each sensor 1-1 to 1-n, each operation end 3-1 to 3-1.
A fieldbus system has been developed in which the 3-n and the control devices 2-1 to 2-n are connected by a single fieldbus 6.

However, since the fieldbus type control device is connected by one fieldbus 6, each sensor 1-1 to 1-n and each control device 2-1 to 2- are connected.
fieldbus 6 between n and each control device 2-1 to 2-
n or any one of the fieldbus 6 between the operating terminals 3-1 to 3-n or the fieldbus 6 between the computing unit 4 and each of the control devices 2-1 to 2-n. Occurs, one signal or a plurality of signals passing through the field bus 6 are interrupted at the same time, and a plurality of sensors 1-
1 to 1-n and operating terminals 3-1 to 3-n are control devices 2-1.
~ 2-n, these control devices 2-1 to 2-
It becomes uncontrollable between n.

For example, when the fieldbus 6 is disconnected between the operating end 3-1 and the sensor 1-2, the process control is performed from the sensor 1-2 to the operating end 3-2, ... Operating end 3-n. Becomes impossible.

In order to prevent such a control failure for the disconnection of the field bus 6, there is a method of duplicating the field bus and backing up the other bus even if one bus is disconnected.

However, in such a method, each sensor 1
-1 to 1-n, each operating end 3-1 to 3-n, and each control device 2-1 to 2-n must be configured to correspond to duplication, which is not economical.

[0013]

When the fieldbus is disconnected as described above, the sensor 1-2 moves to the operating end 3-.
2, ..., The control end 3-n is out of control. Therefore, it is an object of the present invention to provide a fieldbus system control system that can continue basic control even if an abnormality such as disconnection occurs in the fieldbus.

[0014]

According to the first aspect of the present invention, each control loop is formed by at least one detection end, an operation end and a control device, and one detection loop, the operation end and the control device are connected to each other. In a fieldbus type control system connected by a bus, for backup that holds the target signal sent from the control device and outputs the operation signal to the operation end so that the detection signal output by the detection end becomes the target signal. A fieldbus type control system including a control means.

In such a fieldbus type control system, when the bus connecting the detecting end, the operating end and the control device is disconnected, the backup control means holds the target signal sent from the control device. In addition, the operation signal is output to the operation end so that the detection signal output by the detection end becomes the target signal.

According to the second aspect, the backup control means holds the target value holding section for holding the target signal sent from the control device and the detection signal output from the detection end in the target value holding section. A simple control unit that calculates the operation signal to obtain the target signal and outputs the operation signal to the operation end, and an operation signal sent from the control device or an operation signal output from the simple control unit. Is a fieldbus type control system having an operation output holding unit for selecting and outputting to the operation end.

In such a fieldbus type control system, when the bus connecting the detecting end, the operating end and the control unit is disconnected, the target value holding unit holds the target signal sent from the control unit. Then, the held target signal is passed to the simple control unit. This simple control unit
The operation signal is output to the operation end so that the detection signal output by the detection end becomes the target signal.

On the other hand, the operation output holding unit holds the operation signal sent from the control device and outputs it to the operation end, or if the operation signal is sent from the simple control unit, this operation signal is sent to the operation end. Output.

According to the third aspect of the present invention, the target value holding unit is a fieldbus system control system having a function of checking a bus abnormality. In the case of a fieldbus type control system having such a check function, the target value holding unit checks the change in the target signal sent from the control device, for example, and if it judges that there is an abnormality such as disconnection of the bus The target value sent from the device is held by the target value holding unit, and the held target signal is passed to the simple control unit. The simple control unit outputs the operation signal to the operation end so that the detection signal output from the detection end becomes the target signal.

According to the fourth aspect, the operation output holding unit is a fieldbus system control system having a bus abnormality check function. In the case of a fieldbus system control system having such a check function, an operation output is provided. The holding unit checks, for example, a change in the operation signal sent from the control device, and when it determines that there is an abnormality such as disconnection of the bus, holds the operation signal sent from the control device and outputs the operation signal to the operation end, or If an operation signal is sent from the simple control unit, this operation signal is output to the operation end.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The same parts as those in FIG. 4 are denoted by the same reference numerals. FIG. 1 is an overall configuration diagram of a fieldbus type control system according to claims 1 to 4.

The plurality of sensor units 10-1 to 10-n respectively include the sensors 1-1 to 1-n and have a function of outputting a detection signal P corresponding to the process amount. The plurality of control device sections 11-1 to 11-n input the detection signals P sent from the respective sensor sections 10-1 to 10-n, and operate such that the detection signals P become the target signal Q. It has a function of outputting the signal M.

The plurality of operating ends 12-1 to 12-n respectively include operating ends 3-1 to 3-n such as valves, and are sent from the respective control device parts 11-1 to 11-n. It has a function of opening and closing according to each operation signal M that comes in and controlling the process amount.

These sensor parts 10-1 to 10-n, control device parts 11-1 to 11-n and operation end parts 12-1 to 12 are provided.
-N are mutually connected by one field bus 13.

By connecting with one fieldbus 13 in this way, one control loop is formed by, for example, the sensor unit 10-1, the control unit unit 11-1 and the operation end unit 12-1.

This control loop includes sensor units 10-1 to 10-1.
0-n, control device sections 11-1 to 11-n, operation end section 12
Any combination of -1 to 12-n can be set. For example, the sensor unit 10-1, the control device unit 11-
2 and the operating end 12-n may form one control loop, and the sensor unit 10-n and the controller unit 11-1.
Also, one control loop may be formed by the operating end 12-1.

FIG. 2 is a block diagram of one control loop in such a control system. A backup control system 20 is provided in this control loop. The backup control system 20 holds the target signal Q sent from the control unit 11-1 when an abnormality such as disconnection occurs in the fieldbus 13, and the detection signal output by the sensor unit 10-1. It has a function of simply calculating the operation signal Ma so that P becomes the target signal Q and outputting the operation signal Ma to the operation end portion 12-1.

The backup control system 20 is specifically composed of a target value holding unit 21, a simple control unit 22 and an operation output holding unit 23. The backup control system 20 is provided in each control loop.

The configuration of one control loop will be specifically described. In the sensor section 10-1, in addition to the sensor 1-1,
A target value holding unit 21 and a simple control unit 22 are provided. Of these, the target value holding unit 21 is the control device unit 11-1.
Hold the target signal Q sent from the calculator 4 of
It has a function of sending this target signal Q to the simple control unit 22.

The target value holding unit 21 also monitors the change in the target signal Q sent from the arithmetic unit 4, and disconnects the field bus 13 when the change in the target signal Q is different from the normal change. It has a check function of judging that the signal is abnormal and sending a signal indicating this bus disconnection to the simple control unit 22.

When the simple control unit 22 receives a signal indicating the bus disconnection from the target value holding unit 21, the target value holding unit 21.
The target signal Q sent from the sensor 1-1 is input, and the operation signal Ma such that the detection signal P output from the sensor 1-1 becomes the target signal Q is obtained by simple calculation, and the operation signal Ma is obtained. It has the function of sending to -1.

The control device section 11-1 comprises a control device 2-1 and an arithmetic unit 4, and sends various signals 5 to the control unit 2-1 through the arithmetic unit 4 and a target signal obtained by the arithmetic unit 4. Q is input, control calculation such that the detection signal P from the sensor 1-1 becomes the target signal Q, for example, PID calculation is executed, and the operation signal M which is the calculation result is input to the operation end 12-.
It has the function of outputting to 1.

The target signal Q obtained by the computing unit 4
Is sent to the target value holding unit 21 of the sensor unit 10-1.
The operation end 12-1 includes an operation output holding unit 23 in addition to the operation end 3-1.

The operation output holding section 23 has a function of passing the operation signal M normally sent from the control device 2-1 and sending the operation signal M to the operation terminal 3-1. Further, the operation output holding unit 23 monitors a change in the operation signal M sent from the control device 2-1 and, when the change in the operation signal M is different from a normal change, disconnects the field bus 13 or the like. It has a check function of judging that it is abnormal, holding the operation signal M at this time, and sending it to the operation terminal 3-1.

When an abnormality such as a disconnection of the bus is judged by the check function of the operation output holding section 23 itself, the operation signal M from the control device 2-1 is continuously held and the operation terminal 3-
However, when the operation signal Ma is sent from the simple control unit 22 at this time, it has a function of switching to this operation signal Ma and sending it to the operation terminal 3-1.

Next, the operation of the control system configured as described above will be described. The detection signal P output from the sensor 1-1 is transmitted through the field bus 13 to the control device 2-.
Enter 1

The control device 2-1 receives various signals 5 through the arithmetic unit 4 and the target signal Q obtained by the arithmetic unit 4, and the detection signal P from the sensor 1-1 becomes the target signal Q. Such a control operation, for example, a PID operation is executed, and the operation signal M which is the operation result is output to the operation end portion 12-1 through the field bus 13.

In the operation end 12-1, the operation signal M is sent to the operation end 3-1 through the operation output holding unit 23.
As a result, the process amount is controlled to the target value.

Next, the case where an abnormality such as disconnection occurs in the field bus 13 will be described. (a) When the fieldbus 13 between the sensor 1-1 and the control device 2-1 is disconnected, the target value holding unit 21 changes the target signal Q sent from the control device unit 11-1. Therefore, it is determined that an abnormality such as disconnection has occurred in the field bus 13, the target signal Q before the change is held, and the simplified control device unit 22
To send to.

At the same time, the target value holding unit 21 sends a signal indicating that the fieldbus 13 has been disconnected, to the simple control unit 2
Send to 2. The simple control unit 22 is a target value holding unit 2
When the signal indicating the bus disconnection is received from 1, the target signal Q sent from the target value holding unit 21 is input, and the sensor 1
The operation signal Ma such that the detection signal P output from -1 becomes the target signal Q is simply calculated, and this operation signal Ma is sent to the operation end 12-1.

The operation output holding unit 2 of the operation end 12-1
When the operation signal Ma is sent from the simple control unit 22, 3 switches from the operation signal M sent from the control device 2-1 to the operation signal Ma, and this operation signal Ma is set at the operation terminal 3-.
Send to 1.

As a result, the sensor 1-1 and the control device 2-
Even if the field bus 13 between the first and second terminals is disconnected, the sensor 1-1, the simple control unit 22, and the backup control system 20 of the operating terminal 3-1 back up the data and the process control is continuously performed. (b) When the field bus 13 between the control device 2-1 and the operation end 12-1 is disconnected, the operation output holding unit 23 changes the operation signal M sent from the control device 2-1. Is different from the normal change, so at this time, it is determined that the field bus 13 is disconnected, the operation signal M before the change is held, and it is sent to the operation end 3-1.

As a result, the operating end 3-1 opens and closes according to the operation signal M held by the operation output holding unit 23, and controls the process amount. In this state, when the target value holding unit 21 also detects the disconnection of the fieldbus 13 and the operation signal Ma is input from the simple control unit 22 to the operation output holding unit 23, the operation output holding unit 23 holds the held operation. The signal M is switched to the operation signal Ma sent from the simple control unit 22, and the operation signal Ma is changed to the operation terminal 3-.
Send to 1.

As a result, the control device 2-1 and the operating end 1 are
Even if the field bus 13 between 2-1 and 2-1 is disconnected, the operation signal M held by the operation output holding unit 23 or the operation signal Ma sent from the simple control unit 22.
Is backed up and the process control is continued.

The sensor portion 10-1 and the operating end portion 12-
In the case of disconnection from 1 and 1, the operation signal holding unit 23 holds and outputs the operation signal M to open and close the operation terminal 3-1.

As described above, in one embodiment,
Sensor part 10-1, operation end part 12-1 and control device part 1
When an abnormality such as disconnection occurs in the fieldbus 13 connecting between 1-1, the target signal Q sent from the control device 2-1 is held by the target value holding unit 21, and the held target signal Q is held. Is passed to the simple control unit 22 and the operation signal Ma is output to the operation terminal 3-1 so that the detection signal P output by the sensor unit 10-1 becomes the target signal Q. Even if disconnection occurs, the process control can be backed up without interruption and the process control can be continued while performing the simple control.

In this backup, the field bus 13 between the sensor 1-1 and the control device 2-1 and the control device 2 are connected.
Even if the fieldbus 13 between the -1 and the operating end 12-1 is disconnected, the simple control can be continued, and even if the sensor 10-1 and the operating end 12-1 are disconnected. Process control can be continued.

Therefore, with this backup, it is possible to keep the plant operation in the condition that the plant operation can be continued even if any part of the fieldbus 13 is cut.
It can be put to practical use without duplication. Further, since it is not necessary to duplicate the field bus 13, the cost can be reduced and it is economical.

The present invention is not limited to the above-mentioned one embodiment, but may be modified as follows. For example, in the above-described embodiment, the target value holding unit 21 and the operation output holding unit 23 have the function of checking disconnection of the fieldbus 13, respectively. The parts 11-1 to 11-n may be provided.

That is, each control unit 11-1 to 11-
Since n transmits the process data and the operation data to each other according to a predetermined transmission protocol, it is possible to detect that the process data and the operation data have an abnormality when the fieldbus 13 is disconnected. .

Therefore, each control device section 11-1 to 11-n
In this case, the disconnection of the fieldbus 13 is judged from the abnormality of the process data or the operation data,
A signal indicating disconnection may be sent to the target value holding unit 21 and the operation output holding unit 23.

Further, in the above embodiment, the sensor unit 10
-1 to 10-n, the target value holding unit 21 and the simple control unit 22
The target value holding unit 21 and the simple control unit 2 are provided.
2 may be provided on the operation ends 12-1 to 12-n.

Further, when the input of the arithmetic unit 4 of each of the control device sections 11-1 to 11-n is transmitted from another station, in order to cope with disconnection of the transmission from that station, A holding function may be provided for each input.

[0054]

As described in detail above, claims 1 to 5 of the present invention.
According to the fourth aspect, it is possible to provide a control system of a fieldbus system that can be backed up by basic control even if the fieldbus is disconnected and can be kept in a state where plant operation can be continued.

According to the third and fourth aspects of the present invention, the disconnection of the fieldbus is checked in each control loop, and even if the fieldbus is disconnected, backup can be performed by simple control to continue the plant operation. It is possible to provide a fieldbus type control system that can keep the situation.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a first embodiment of a fieldbus control system according to the present invention.

FIG. 2 is a specific configuration diagram of one control loop in the control system.

FIG. 3 is a configuration diagram of a conventional process control device.

FIG. 4 is a configuration diagram of a process control device to which a conventional fieldbus system is applied.

FIG. 5 is a specific configuration diagram of one control loop in the control system.

[Explanation of symbols]

1-1 to 1-n ... Sensor, 3-1 to 3-n ... Operating end, 4
... arithmetic unit, 10-1 to 10-n ... sensor section, 11-1 to 11-
11-n ... Control device section, 12-1 to 12-n ... Operating end section, 13 ... Fieldbus, 20 ... Backup control system, 21 ... Target value holding section, 22 ... Simple control section, 23 ... Operation output holding Department.

Claims (4)

[Claims] 1. A control loop is formed by at least one detection end, an operating end and a control device, and these detection ends,
In a fieldbus type control system in which an operating end and a control device are connected by a single bus, a target signal sent from the control device is held,
A fieldbus system control system comprising: backup control means for outputting an operation signal to the operation end so that the detection signal output by the detection end becomes the target signal. 2. The backup control means holds a target value holding unit that holds a target signal sent from the control device, and a detection signal output from the detection end is held in the target value holding unit. A simple calculation is performed to obtain the target signal to obtain an operation signal, and the simple control unit that outputs the operation signal to the operation end, the operation signal sent from the control device, or the simple control unit outputs the operation signal. 2. The field bus system control system according to claim 1, further comprising: an operation output holding unit that selects the selected operation signal and outputs the selected operation signal to the operation end. 3. The field bus system control system according to claim 2, wherein the target value holding unit has a function of checking the bus abnormality. 4. The field bus type control system according to claim 2, wherein the operation output holding unit has a function of checking the bus abnormality.