JPH10320017A - Field communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a field communication system which improves the precision of a control operation by detecting the operation execution cycle of each device through communication and changing the operation cycle of each device. SOLUTION: An operation controlling part 20 operates process data which are inputted from a device controlling part 6 and a device data inputting part 19, sets data for communication and time cycle output data and stores the in a data outputting part 21 and a time cycle outputting part 22. A data transmitting and receiving part 13 sends data of the parts 21 and 22 to a field bus 4 through a network controlling part 12. A controlling part 12 of other blocks transfers data for self-station to the part 13 from the bus 4, takes out time cycle data and outputs it together with other data to a time cycle inputting part 14. The part 14 decides a time cycle updation cycle and stores it in a preservation memory part 15, and an operation execution controlling part 18 controls the data supply of the part 15 to an operation controlling part 20. It inputs data of the part 15 in the part 20 through a preservation data selecting part 16 and carries out a control operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system in which devices distributed in a field are connected by a field bus, and an arithmetic function (function block) provided in each device.
The present invention relates to a field communication system for exchanging input / output data via communication and performing arithmetic control of a process with a set of arithmetic functions of a plurality of devices.

[0002]

2. Description of the Related Art A field bus system is, for example, a self-contained distributed field bus system described in Japanese Patent Application Laid-Open No. 4-195201, in which a higher-level device installed in an instrument room and a field device are arranged. It is composed of a plurality of detection / control blocks and a bus line connecting the upper devices and the plurality of blocks.

Each of the plurality of detection / control blocks has a detection end device, an operation / control means, and an operation end device, and independently forms a control loop. Then, based on the calculated value detected by the detecting end device, a control signal is generated by the operation / control means using a built-in control parameter, and the operating end device is operated by the control signal to perform a control operation.

[0004]

However, in the above-mentioned conventional field communication system, a case where a control operation is performed by using arithmetic and control of each device which is distributed and installed is described.
There is a problem.

That is, the operation execution cycle of the detection end input, operation / control, and operation end output of each device is determined by the execution period of each device. Due to the difference, for example, when the differential operation is performed by the control operation, the following problem occurs.

[0006] 1. When the execution cycle of the detecting end is slow and the operation of the control arithmetic unit is fast, the output result of the differential operation is reduced as compared with a case where the output is realized by a single device. 2. When the execution cycle of the detection end is early and the control operation side is late, the differential output increases. Further, a phenomenon occurs in which the sudden change signal detected at the detection end cannot be obtained on the control operation side. An object of the present invention is to provide a field communication system capable of improving the accuracy of control operations by detecting the operation execution cycle of each device via communication and enabling the operation period of each device to be changed based on the detected operation period. It is to realize the system.

[0007]

[Means for Solving the Problems]

(1) The present invention is configured as follows to achieve the above object. In other words, a higher-level device and a plurality of field devices are connected by a field bus, and the arithmetic functions provided to the respective devices on the field bus mutually transmit and receive operation data via the field bus, thereby controlling the operation. In a field communication system that constructs a loop, each of the plurality of field devices includes a time cycle input / output unit that adds processing cycle data for each execution cycle of the device to operation data, and an update cycle of the time cycle input / output unit. And a calculation execution control unit that executes control calculations of the devices, and makes the calculation cycle of the calculation control loop substantially the same.

(2) Preferably, in the above (1),
Each of the plurality of field devices further includes a holding memory unit that holds a plurality of pieces of data for each processing cycle, and a holding data selection unit that can select the processing cycle data held in the holding memory by calculation. In addition, calculation control is performed without losing sudden changes in input / output and calculation data due to differences between calculation cycles.

(3) In addition, the above-mentioned device and a plurality of field devices are connected by a field bus, and the calculation function provided for each device on the field bus allows the calculation data of the calculation data to be mutually exchanged via the field bus. In a field communication system that performs transmission and reception and constructs an arithmetic control loop,
Each of the plurality of field devices includes a calculation cycle setting means for mutually setting a calculation cycle of a device on the field bus via the field bus.

[0010] The time cycle input / output unit monitors the update of input data from other devices used for calculation and control, and outputs a data update delay signal when the data update is slow. If data update is early, a data update promotion signal is output. The calculation execution control unit receives the data update delay signal or the data update promotion signal, and delays or advances the start of the calculation execution. Further, the time cycle input / output unit receives the output of the calculation execution result and counts update data of the calculation cycle.

The holding memory section internally holds input data from another device, and erases the held data other than the latest input data upon completion of the operation. The held data selection unit outputs the input data stored in the held memory unit to the operation control unit as communication data input for operation. At this time, when a plurality of data are present in the holding memory unit, the data is output to the arithmetic control unit according to the setting of the holding data selection unit.

As described above, even if the calculation cycle of another device is different from the calculation cycle of the own device, the execution at the unified calculation cycle can be performed by making the execution cycle of the calculation and control correspond to the calculation update cycle. Achieved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a field device in a field communication system according to an embodiment of the present invention, and FIG. 2 is an overall schematic configuration diagram of the field communication system.

First, a field communication system will be described with reference to FIG. The devices 1a, 1b,..., Which are detection devices that measure the amount of process installed in the field, the operation device 2 that outputs a control output as an operation output signal, and monitors the process amount, control amount, and operation output signal of each device. Host computer 3 for monitoring process control or setting control parameters
Are connected by a field bus 4 on the bus. Then, data of the operation results of these devices 1a, 1b, 2 and the host computer 3 are exchanged with each other via the field bus 4.

The detecting end devices 1a, 1b,... Obtain sensors 5a, 5b for detecting a process amount and signals extracted from the sensors 5a, 5b as measurement signals.
a and a device controller 6 for performing correction and settling of 5b.
Also, the detection end devices 1a, 1b,... Receive arithmetic operation control units 7a, 7b for performing arithmetic processing such as linearization, bias, and に on measurement signals, and receive input data for arithmetic control from other devices, Communication control units 8a and 8b for transmitting data of the calculation result to other devices.

The operating end device 2 includes a control valve, an electromagnetic valve instead of the communication control unit 8-2, the arithmetic control unit 7-2, the device control unit 6-2, and the sensors 5a and 5b of the detecting end devices 1a and 1b. And the like. Then, the device control unit 6-2 outputs or corrects the operation amount of the operation end to the operation output signal.

The upper-level computer 3 includes a communication controller 8c for transmitting and receiving data such as detection signals, control signals, and operation signals of the field devices 1a, 1b,..., And displaying the transmitted and received data on the display 10. Or a screen display / setting controller 9 for transmitting a setting signal from the operator to each of the field devices 1a, 1b,... 2 via the communication controller 8c.

Next, in FIG. 1, the field devices are:
As control of the device itself, a device control unit 6 for taking in a sensor signal from a process in the case of a detection end device or outputting to a manipulator in the case of an operation end is provided.

The field device receives a signal from the device control unit 6 and calculates a real value for calculation, a 0-100% value,
~ 1.000 Device data input unit 1 for creating numerical data
9 and an operation control unit 20 that receives an operation start, executes an operation function, such as an input operation, a PID operation, an output operation, an alarm operation, and a logical operation, which is previously mounted on each device, and outputs an operation result.
And a data output unit 21 for temporarily storing operation data. The device data input unit 19, the operation control unit 20, and the data control unit 21 constitute the operation control units 7a and 7b shown in FIG.

The field device includes a network control unit 12 and a data transmission / reception unit 13. And
The network control unit 12 receives a packet or a token for transmission permission for each device from the field bus 4 and transmits data if the own device has a data transmission request from the data transmission / reception unit 13. Alternatively, when data addressed to the own device is received, communication control for transferring data to the data transmitting / receiving unit is executed.

The data transmission / reception unit 13 removes data such as a destination address, a transmission source address, frame control information, and the number of frame bytes from the data received by the network reception control unit 12 as data for operation control. And data reception processing that extracts only the time cycle data and data output from the operation result, and adds the time cycle of operation execution and the destination address, source address, frame control information, and frame byte number for data transmission, and data transmission processing I do.

The field device includes a time cycle input unit 14, a holding memory unit 15, a held data output selection setting unit 17, a held data selection unit 16, an arithmetic execution control unit 18, a time cycle output unit 22 And

The time cycle input section 14 receives the time cycle data, compares the time cycle data with the previous time cycle stored in the holding memory section 15, outputs an updated value, determines the update cycle of the input data, and outputs an operation execution signal to the operation execution control section. 18 is output. Further, the holding memory unit 15 stores the operation input data and the time cycle data for each received data, and erases the data other than the latest data when the operation is completed.

The held data output selection setting unit 17
Which of the instantaneous value (latest data), the average value, the maximum value, the minimum value, and the amount of change (in the case where a plurality of data are held) is input to the calculation as the data stored in the holding memory unit 15. Select whether to use data. Further, the held data selection unit 16 creates input data for calculation in accordance with the setting of the held data output selection setting unit 17.

The calculation execution control unit 18 starts the execution of the calculation in response to the calculation execution signal from the time cycle input unit 14, and releases the execution when the calculation is completed. Further, the time cycle output unit 22 counts the operation time cycle as the number of updates or stores the value as the value of the internal clock, and outputs it to the data transmission / reception unit 13. 1 includes a time cycle input unit 14, a holding memory unit 15, a held data output selection setting unit 17, a held data selection unit 16, an arithmetic execution control unit 18, and a time cycle output unit 22. The communication control units 8a and 8b are configured.

Next, the operation of the field device shown in FIG. 1 will be described with reference to the AI operation block (device 1) shown in FIG.
The operation of adjusting the calculation cycle with the calculation block (device 2) is described as an example. In the example shown in FIG. 3, the operation cycle of the AI operation block is later than the PID operation cycle.
This is an example of a case where operation data of an operation block is transmitted to a PID operation block. FIG. 4 is a flowchart of the operation of the AI operation block and the device control operation, and FIG.
It is an operation | movement flowchart of the transmission process of an AI calculation block. FIG. 6 is a flowchart of a PID calculation block receiving operation, and FIG. 7 is a flowchart of a PID block calculation and device control operation.

First, the operation of the AI operation block will be described. In step 100 of FIG. 4, the device control unit 6
Capture data from the process. Next, step 10
In 1, the arithmetic control unit 20 calculates data fetched from the device control unit 6 into the arithmetic control unit 20 via the device data input unit 19 to create data. Then, in step 102, the arithmetic control unit 20 sets the calculated data as communication data and sets time cycle output data (data indicating a calculation cycle or a sampling cycle). Next, in step 103, the arithmetic control unit 20 determines whether or not an arithmetic operation cycle has been reached. If it is determined in step 103 that the calculation cycle has been reached, in step 104, the calculation control unit 20 stores the set communication data in the data output unit 21 and stores the set time cycle data in the time cycle output unit 22.
To be stored. Then, the process returns to step 100, and repeats steps 100 to 104 described above.

Next, in step 200 of FIG. 5, the data transmission / reception section 13 determines whether or not there is data to be transmitted. Then, in step 201, the data transmission / reception unit 13 determines whether or not a transmittable frame indicating that transmission is possible is received from the network control unit 12, and if received, proceeds to step 202. Step 20
2, the data transmission / reception unit 13 includes the data output unit 21
Data and time cycle output unit 2 stored in
Fetch the time cycle data stored in 2
Via the network controller 12, the field bus 4
The communication data and the time cycle data are transmitted.

Next, the operation of the PID operation block will be described. In step 300 in FIG. 6, the network control unit 12 determines whether or not there is communication data addressed to the own station among the data communicated via the field bus 4. In step 300, if there is communication data addressed to the own station, the process proceeds to step 301, where the network control unit 12 transfers the communication data addressed to the own station to the data transmitting / receiving unit 13.

Next, in step 302, the data transmitting / receiving unit 13 determines whether or not the transferred data is data from the AI operation block. After performing the appropriate receiving process, the process ends. If it is determined in step 302 that the transferred data is data from the AI operation block, the process proceeds to step 304. Then, in step 304, the data transmission / reception unit 13 extracts time cycle data from the transferred data and outputs it to the time cycle input unit 14 together with other data.

Next, in step 305, the time cycle input unit 14 determines the time cycle update cycle, and in step 306, stores the data in the holding memory unit 15. Then, in step 307, the arithmetic execution control unit 18 controls to take out the data stored in the holding memory unit 15 at an arithmetic cycle and supply the data to the arithmetic control unit 20.

Next, in step 400 of FIG. 7, the device control section 6 outputs a control signal to the process and performs a control operation of the process. Next, in step 401,
The data stored in the holding memory unit 15 is input to the arithmetic and control unit 20 via the holding data selection unit 16. Then, in step 402, the operation control unit 20 executes an operation necessary for control based on the input data. Next, in step 403, the arithmetic control unit 20 sets the control output to the device control unit 6 and sets the time cycle output data. Then, in step 404, the arithmetic control unit 20 determines whether or not it is an arithmetic cycle,
When the calculation cycle comes, the process returns to step 400, and thereafter, steps 400 to 404 are repeated.

FIG. 8 shows the operation cycle of the AI operation block,
9 is a graph showing a state in which the operation cycle of the PID operation block is synchronized. As shown in FIG. 8, the sampling period of the PID operation block is delayed,
It is synchronized with the sampling cycle of the AI operation block.

Although the above description is for the case where the operation cycle of the AI operation block is slower than the PID operation cycle, the same applies to the case where the operation cycle of the AI operation block is faster than the operation cycle of the PID operation block. The operation cycle of the operation block is adjusted and synchronized with the operation cycle of the AID operation block.

FIG. 9 shows that the operation cycle of the AI operation block is
9 is a graph showing a state in which the operation cycle of the PID operation block is adjusted when the operation cycle is later than the PID operation cycle. As shown in FIG. 9, the sampling period of the PID operation block is shortened and synchronized with the sampling period of the AI operation block.

As described above, according to the embodiment of the present invention, each of the devices 1a,
When control is performed using the calculation functions 1b ... 2, each device can be controlled in a calculation cycle synchronized with the input data only by adding the time cycle data of the calculation cycle to the input data, and the accuracy of the control operation can be improved. A simple field communication system can be realized.

The above-described example is an example in which the operation cycle of each device is synchronized. However, not only the example of synchronizing, but also the receiving side (the other side) using the added time cycle data.
An embodiment in which the calculation cycle of is set to an appropriate cycle according to the control operation of the transmission side can be realized.

That is, the operation control unit (operation period setting means)
According to 20, when setting the time cycle data, the time cycle data can be set so that the operation cycle is different from that of the own station for the convenience of the control operation. With such a configuration, it is possible to extend or simplify an arbitrary control operation, and to realize a field communication system capable of expanding a control application range.

Although an example in which time cycle data is added to the operation data to synchronize the operation period has been described, the operation execution control unit 18 transmits the data to the input data device via the data transmission / reception unit 13 and the network control unit 12. It is also possible to read the operation cycle of the other party directly from the side, control the read operation cycle, and synchronize the operation cycle.

[0040]

Since the present invention is configured as described above, it has the following effects. When controlling using the arithmetic function of each device connected on the field bus,
It is possible to realize a field communication system which can be controlled with a synchronized calculation cycle only by adding time cycle data of the calculation cycle to the input data.

If the time cycle data is set so that the operation cycle is different from that of the own station for the sake of control operation, any control operation can be extended. Thus, it is possible to realize a field communication system which can be simplified or simplified and can extend the applicable range of control.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a field device in a field communication system according to an embodiment of the present invention.

FIG. 2 is an overall schematic configuration diagram of a field communication system.

FIG. 3 is a diagram showing an example of a device for explaining the operation of the embodiment of the present invention.

FIG. 4 is a flowchart of the operation of the AI operation block and the device control operation.

FIG. 5 is an operation flowchart of a transmission process of an AI operation block.

FIG. 6 is a flowchart of a reception operation of a PID operation block.

FIG. 7 is a flowchart of PID block calculation and device control operations.

FIG. 8 is a graph showing an example of a state in which the operation cycle of the AI operation block and the operation cycle of the PID operation block are synchronized.

FIG. 9 is a graph showing another example in which the operation cycle of the AI operation block and the operation cycle of the PID operation block are synchronized.

[Explanation of symbols]

 1a, 1b device (detection end) 2 device (operation end) 3 host computer 4 field bus 5a, 5b sensor 6, 6a, 6b, 6-2 device control unit 7a, 7b, 7-2 operation control unit 8a, 8b, 8-2 Communication control unit 9 Screen display / setting control unit 10 Display 12 Network control unit 13 Data transmission / reception unit 14 Time cycle input unit 15 Holding memory unit 16 Holding data selection unit 17 Holding data output selection setting unit 18 Calculation execution control unit 19 Device data input unit 20 Operation control unit 21 Data output unit 22 Time cycle output unit

Claims (3)

[Claims] An upper device and a plurality of field devices are connected by a field bus, and operation data of the operation controller provided in each device on the field bus are mutually connected via the field bus. In the field communication system which constructs an operation control loop by transmitting and receiving data, each of the plurality of field devices includes a time cycle input / output unit for adding processing cycle data for each execution cycle of the device to the operation data; A field communication system, comprising: a calculation execution control unit that executes a control calculation of a device at an update cycle of an input / output unit, wherein a calculation cycle of a calculation control loop is made substantially the same. 2. A field communication system according to claim 1, wherein each of said plurality of field devices further holds a plurality of data for each processing cycle, and a processing cycle holding said data in said holding memory. A field data communication system comprising: a held data selection unit that allows data to be selected by calculation; and performing calculation control without losing sudden changes in input / output and calculated data due to differences between calculation cycles. . 3. The device and a plurality of field devices are connected by a field bus, and the calculation function of a calculation control unit provided for each device on the field bus allows calculation data to be mutually transmitted via the field bus. In the field communication system for constructing an operation control loop, the plurality of field devices each set an operation period of a device on the field bus via the field bus via the field bus. A field communication system comprising: