JPS6049321B2 - process control equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process control device using a calculator.

More specifically, the present invention relates to a process control device equipped with backup means in case of computer failure. In a process control device using a computer, the computer controls a plurality of control objects in a time-sharing manner, so if the computer malfunctions, it will have a large impact.

Therefore, a backup device is provided to reduce the effects of computer failure. As a backup device, an analog controller is usually used and is installed for each control loop that requires backup. In order to ensure smooth backup in the event of a computer failure, each analog controller tracks the control output of the computer. It is necessary to have control parameters.In such conventional equipment, the same control parameters must be given to the computer and analog controller for each controlled object that requires backup; are different devices, so
It is complicated because it has to be given separately in a way that suits each person.

Furthermore, since there are few common parts between the computer (computer) and the analog controller, the amount of hardware required increases when backup is performed, which is not economical. When a process control computer is combined with a higher-level computer, the higher-level computer may perform backup in the event of a failure of the process control computer.

In this case, the two computers must have databases with the same contents regarding process control in order to perform backup and restoration smoothly. However, 2
Since the two computers have separate memories, the database of the process control computer must be uploaded to the higher-level computer before a failure occurs, and the database of the higher-level computer can be downloaded to the process control computer after the failure has been recovered.
Special operations are required for database optimization. An object of the present invention is to replace a computer that controls multiple loops with a single loop control unit using a microprocessor.
The object of the present invention is to provide a process control device having a reasonable memory configuration for matching databases when backing up every loop.

As a method for matching the contents of memory between two computers having an equal relationship, a method is known in which a common memory is used by both computers.

If this method is applied to two computers that are in a higher-ranking and lower-ranking relationship, it is possible to match the databases of both computers, but since the roles of the higher-ranking computer and the lower-ranking computer are naturally different, each It is desirable to share memory in a reasonable manner according to the role of each person. The present invention will be explained below with reference to the drawings. FIG. 1 is an external view of an embodiment of the present invention. In FIG. 1, 1 is the main body of the control device, 11 is its terminal board cubicle, and 12 is the control cubicle. 2 is a display/operation device, 21 is a CRT display, 22 is a backup table. It is an indicator/operator.

The control device main body 1 and the display/operation device 2 are connected by a cable routed under the floor. 3 is a controlled process.

The controlled process 3 is connected to the control device body 1 through the instrumentation wiring 4.
It is tied with. FIG. 2 shows the internal connections of the control device main body 1 and the connection system diagram among the control device main body 1, the display/operation device 2, and the controlled process 3.

However, FIG. 2 shows only the parts necessary for explaining the present invention. The terminal board ●cubic unit 11 of the control device main body 1 includes an analog control board ACB. The analog control board ACB has a plurality of input/output converters RGC corresponding to the objects to be controlled. Control ● Calculation for cubicle 12? Contains the CU and its interface AGN. Interface A
GN has multiple loops corresponding to the control loop●Unit A
Has BO. These loop units ABO are the backup display/operator 22 in the display/operator 2.
connected to. The backup display/operation device 22 has a plurality of display/operation units ABU corresponding to the loop unit ABO. The display/operation unit ABU has an input indicator, an output indicator, an output operator, etc., similar to the display/operator of an analog controller. Display/operation device 2
The CRT display 21 in 2 is connected to a computer SCU (not shown). The signal system diagram in FIG. 2 is shown in FIG. 3.

a) Analog control ● The input/output converter RGC on the board ACB converts the analog measurement signal given from the detection end of the process into an intermediate signal and transmits it to the loop ● unit M, and the input/output converter RGC is given from the loop unit ABO. The intermediate signal is converted into an analog operation signal and transmitted to the operation end of the process. A pulse width signal is used here as the intermediate signal. Loop unit AB
O is input switch positive L1 output multiplexer MPXl memory input converter PW/C1 memory output converter C/PWl
Memory M1 microprocessor μ, isolation
It has a block ISO1 and an auxiliary input/output switch SW. The intermediate signal given from the input/output converter RGC is given to the memory input converter PW/C through the input switch SEL, where it is converted into a digital signal and sent to the memory M.
is written as input MEAS. Output data 0UTPUT in memory M is converted into an intermediate signal by memory output converter C/PW and applied to input/output converter RGC through output multiplexer MPX. Does memory M contain settings in addition to input/output data? E.T. ．． Control parameters such as PID constants and status information are stored in a database structure and form part of the memory of the computer SCU. The computer SCU performs control calculations for the loop using the data in the memory M, and outputs the obtained results 0U.
Write to memory as TPUT. The computer SCU also processes various data within the loop unit N°C. The calculation CU sequentially performs such operations for each loop unit and performs comprehensive data processing across multiple loops to perform process control. The microprocessor μ is a backup intelligence for the computer SCU, and when the computer CU fails, the data in the memory M is used instead to perform loop control calculations and data processing in the loop unit ABO.
The memory M constitutes a part of the memory of the computer SCU, and also serves as the memory of the loop unit ABO.

That is, memory M stores loop unit. It is located inside the ABO and serves as a shared memory between the computer SCU and the microprocessor μ. Since such a shared memory M stores a database regarding the loop, it is necessary and sufficient for both the computer SCU and the microprocessor μ to process data regarding the loop. Isolation Block I
The SO converts the two outputs of the multiplexer MPX into analog voltages using pulse width/voltage converters PW/Vl and PW/V2, and outputs them insulated.

Input MEAS by pulse width/voltage converter PW/V1
Either the set value SETl constants P, I, Dl or other control parameters are output, and the output 0UTPUT is outputted by the pulse width/voltage converter PW/2.
The isolation block ISO also isolates and outputs the status information in the memory M by means of the status output device STO, and provides isolated external status signals to the memory M by means of the status input device STI. Isolation●The input and output of the block ISO are connected to the display●operation unit ABU. Auxiliary input/output switch SW
is used to give external input to the input switch SEL or output the output of the multiplexer to the outside, and is connected to other loops.
This allows for cascade connections with other units. If the configuration of the loop●unit ABO is shown in more detail,
It will look like Figure 4.

In FIG. 4, parts similar to those in FIG. 3 are given the same symbols, but the arrangement of figures has been partially changed for convenience of drawing. What is omitted in FIG. 3 and shown for the first time in FIG. 4 are the memory data bus DB1, data selector DSL1, memory address bus dove, address selector ASL1, timing generator TM1, and various control signal lines. Data read from and written to memory M is transmitted on data bus DB.

The data bus DB is connected to the data selector DSL.
Computer SCU write data and memory input converter PW/
The write data of C is combined. data selector DSL
is controlled by a microprocessor μ to select either one of the data. Write data from the status input device STI is also coupled to the data bus DB. Data bus DI3l. The read data is coupled to the computer SCU, the memory output converter C/PW, and the status output TO. Memory output converter C/PW
The setting of read data to and status output STO is controlled by the microprocessor μ. Data bus DB is also coupled with read and write data from the microprocessor μ.

Addresses for reading and writing data to and from memory M are given to memory M from computer SCU and microprocessor μ through address bus AD and address selector ASL.

The address selector ASL is controlled by the microprocessor μ and selects an address given from the computer SCU and an address given from the microprocessor μ.
Choose one. Memory M is provided with read/foot control signals by microprocessor μ.

Control signals are exchanged between the computer SCU and the microprocessor μ.

This control signal is used to notify each other of memory access requests to avoid conflicts in memory use. Also, from the computer SCU to the microprocessor μ,
A fail signal is given as a condition for the microprocessor μ to start backing up the process control and for its cancellation. The timing generator TM generates a synchronization signal and a clock signal, and provides the synchronization signal to the microprocessor μ, the input switch SEL, and the output multiplexer MPX.
A clock signal is provided to the memory input converter PW/C and the memory output converter C/PW.

The synchronization signal is, for example, a rectangular wave with a period comparable to that of a commercial AC power source, and the clock signal is a pulse with a much shorter period. The input switch SEL and the output multiplexer MPX are controlled by a synchronizing signal and alternately switch two input (output) signals each half cycle.

Memory input converter PW/C and memory output converter C/PW
utilizes a clock signal to perform pulse width to code conversion and code to pulse width conversion, respectively. Microprocessor P switches the input based on the synchronization signal? Writing of input data to memory input converter PW/C, reading of output data for memory output converter C/PW, and switching control of data selector DSL are performed in accordance with the periodic operation of EL and output multiplexer MPX. Let's do it.

The microprocessor μ is a status input (output) device ST
I, STO data reading and writing is also based on the synchronization signal,
This is done periodically at a predetermined timing.

Reading and writing data in memory M is performed by microprocessor μ.
It is controlled by a read/write control signal given to memory M from. When reading and writing such input/output data, the address selector ASL is controlled to select the address given by the microprocessor μ.
At other times, the address given by the computer is selected. Similarly, the data selector DSL periodically transfers data from the memory input converter PW/C to the memory M.
The data in the memory input converter PW/C is selected only when writing to the memory input converter PW/C, and the data given from the computer SCU is selected at other times. While the computer SCU is normal, the microprocessor μ only performs periodic data input/output as described above, and data processing for process control is performed by the computer SCU in the database of the memory M. It is carried out on the basis of

When the computer SCU accesses the memory M in its data processing process, the computer SCU provides a control signal to the microprocessor μ to cause the microprocessor μ to generate a read/write control signal for the memory M. When the computer SCU fails, the microprocessor μ starts data processing to back up process control based on the fail signal. It also performs memory access for data processing.

Returning to FIG. 3, there are two types of display/operation units, which can be used depending on needs.

ABU is a standard type, and ABU'' is a type with a tuning mechanism for multiple parameters.In the standard type display/operation unit ABU, 221 is a status changeover switch;
22 is an input indicator, 223 is a tuning switch,
224 is a status indicator, 225 is an output indicator, 22
6 is an operation switch. ) The input indicator 222 and the output indicator 225 are isolated block ISO
Pulse width ● Indicates the output of voltage converters PW/Vl and PW/V2, respectively. The status changeover switch 221 is for changing the control mode, and has three positions: control/mode CTL1 by the computer SCU, backup manual mode BM1, and backup automatic mode BA. The tuning switch 223 enables tuning of the set value. When this switch is pressed in the backup manual mode BM or the backup automatic mode BA, the input indicator 222 will indicate the set value SET instead of the input MEAS. If the operating switch 226 is operated in this state, the set value SET can be increased or decreased. The operation switch 226 is a non-locking three-position switch with a neutral position, and in the backup manual mode BM or the backup automatic mode BA, the amount of operation can be increased by tilting it upward, and decreasing it by tilting it downward. The output of the manipulated variable is 0 until the tuning switch 223 is pressed.
UTPUT1 it is pressed /
When this happens, set value SE as described above.
It is T. The contact status of each switch is given to loop unit M as external status information, and computer SC
It defines the operation of U or microprocessor μ. Status information from loop unit ABO is displayed on status indicator 224. The status display 224 indicates when the computer SCU loses control of the loop, that is, when a failure occurs in the computer SCU and the output freezes.
Lights up to display when backup manual mode BM or backup automatic mode BA is entered. A display/operation unit ABU'' having a tuning mechanism for multiple parameters has a similar structure, but further includes a parameter selector 227.

Parameter Selector 227 consists of a thumbwheel switch, and is used to set the tuning target.
Any one of the SETl constants P, I, D or other parameters can be selected. Parameter ●The contact state of switch 227 is loop unit AB.
It is given to O as external status information. When the tuning switch 223'' is pressed in the backup manual mode BM or the backup automatic mode BA, the value of the parameter selected by the parameter selector 227 is indicated on the input indicator 222'', and the operation switch 226'' is then operated. Then, the value of the parameter can be adjusted.The operation of the device configured in this way is as follows.The analog measurement signal given from the detection end of the process is sent to the analog control board ACB.
It is converted into an intermediate signal by the input/output converter RGC, and the loop
It is converted into a digital signal by the memory input converter PW/C of the unit ABO, and written into the memory M as an input MEAS. The output 0UTPUT stored in the memory M is converted into an intermediate signal by the memory output converter C/PW,
The output signal is applied to the input/output converter RGC of the analog control board ACB through the output multiplexer (■■), where it is converted into an isolated analog operation signal and applied to the operation end of the process. Such input/output of memory data to/from the process is extremely easy since the memory M is located within the loop unit. That is, it is reasonable to place shared memory within the loop unit. The output 0UTPUT in the memory is calculated by the computer SCU, and the value of the input MEAS is set to the set value S.
Since the value is set to match ET, the controlled object of the loop is controlled to match the set value. Similar operations are performed in all loop units to accomplish process control. In this way, the computer SCU uses the database stored in the memory M of each loop unit N to calculate the operation output of each loop, and also performs various data processing for comprehensive process control. The operator is a CR connected to the computer SCU.
The T-display provides comprehensive process monitoring and operation. The status of each loop●unit ABO is indicated by the backup display, each display of the operating device 22, and the operating unit ABU (
or ABU'').

While the computer SCU is controlling the loop, the input MEAS is instructed to the input indicator 222, and the output indicator 225
is instructed to output 0UTPUT. At this time, the status changeover switch 221 is set to CTL. When the computer SCU fails, control of each loop is transferred to the microprocessor P in the respective loop unit ABO.

At this time, each microprocessor μ takes over the data in the memory M and performs control calculations and other data processing for the loop. Until then, the data in memory M was stored in computer S.
Since it was used by the CU, bumpless backup can be performed by taking over and controlling it. In addition, the hardware used by the microprocessor μ is similar to the loop used by the computer SCU until then.
The hardware below the unit is used as is. When control is transferred to the microprocessor P, the status display 224 of each display/operation unit ABU of the backup display/operator 22 lights up.

The operator thereby knows that the backup state has been entered. If the computer SCU malfunctions, monitoring and operation using the CRT display 22 connected to it will no longer be possible, so from now on, the operator must use the display/operation unit A.
Monitoring and operation will be performed by the BU. Calculator S
When control is transferred to the microprocessor μ due to a failure of the CU, the output may be frozen immediately, or the control may be continued by immediately switching to backup automatic mode, which method is determined in advance. It is being

When the output is frozen, the operator needs to judge the situation and select either to switch to backup manual or automatic mode, or to continue freezing when the status indicator lights up. In the backup automatic mode BA, the microprocessor μ calculates the output 0UTPUT according to the O difference between the input MEAS and the set value SET, and performs automatic control.

If the operator wants to manually operate the control output, use the status changeover switch 221 of the display/operation unit ABU.
Switch to BM.

Then, the status signal given to the loop ● unit ABO changes, and the microp 5-mouth processor μ stops its control calculation and becomes ready for manual operation. When the operation switch 226 is operated to issue an increase/decrease command, the microprocessor μ increases or decreases the output 0U'IPUT in the memory M at a constant rate while the command continues. Output 0UTPUT in memory M is output indicator 2
25, the operator outputs 0UTP.
You can perform operations while watching changes in UT. Even in the manual mode, the output 0UTPUT in the memory M is inherited as is, so switching is performed bumplessly. When the status changeover switch 221 is switched to BA, the backup automatic mode BA is returned to, the contents of the memory M are taken over, and the automatic control is switched bumplessly.

In backup manual or automatic mode, when the operator wishes to change control parameters, he or she presses tuning switch 223.

Then, the setting value SET is instructed to the input indicator 222 instead of the input MEAS. In this state, if an increase/decrease command is given using the operation switch 226, the set value SET in the memory M will be increased or decreased, and this will be indicated on the manual power indicator 222, so the operator can change the set value SET to the desired value. be able to. When ABU'' is used as the display/operation unit, the constants P, I, D, etc. can also be changed. When the computer SCU has been repaired, the status changeover switch 221 is returned to CTL.

As a result, the contents of the memory M are taken over by the computer SCU, and the computer mode is restored bumplessly. Note that switching to the backup mode can be performed not only when the computer SCU malfunctions, but also at any time by the operator using the status changeover switch 221. In this way, according to the present invention, a computer that controls multiple loops can be
When a single loop control unit using a microprocessor is used to back up each loop, a process control device with a reasonable memory configuration for database matching can be realized.

In addition, the loop unit M℃ normally operates to control each loop by performing control calculations, and the computer SCU sets or changes the control parameters of each loop unit M℃ while determining the overall situation. It has a logical structure that allows it to be used not only as a backup control but also as an SPC control or adaptive ●
It is also possible to develop it as a controller.

[Brief explanation of drawings]

FIG. 1 is an external view of an embodiment of the present invention, FIG. 2 is a connection system diagram of its main parts, FIG. 3 is a signal system diagram thereof, and FIG. 4 is a detailed diagram of a part of FIG. 3. 1... Control device main body, 11... Terminal board ● Cubicle, 12... ● Control ● Cubicle, 2... Display/operation device,
21...CRT display, 22...Backup display/operation unit, 3...Controlled process, ACB...analog control board, RGC...
...Input/output converter, SCU...Computer, AG
N...Interface, ABO...Loop Unit, ABU...゜Display/operation unit, S
EL...Input switch, ■■...Output multiplexer, PW/C...Memory input converter, C/PW...Memory output converter, M...
・・Memory, μ・・・・Microprocessor, IS
O...Isolation ●Block.

Claims (1)

[Claims] 1. A loop unit provided for each unit loop of process control, a display/operation unit provided for each loop unit, and a plurality of loop units for process control. A process control device having a computer that processes data, wherein the loop and
The unit includes a memory that stores input/output data and control parameters regarding the unit loop in a database structure and forms part of the memory of the computer, and when the computer ceases to process data regarding the unit loop; a processor that obtains the right to use this memory and performs data processing including control operations for the unit loop; a means for coupling the input/output data of the memory to a control target; and a means for coupling the data of the memory to the display/operation unit. A process control device characterized by having means for.