JP2973586B2 - 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 in which a programmable controller (PC) used for automating various machines can be connected to a control device for controlling a process. And controllability when a PC is connected to the control device.

[0002]

2. Description of the Related Art Distributed control devices are widely used in the field of process control. On the other hand, programmable
A controller (PC) has been used as an automatic device of a device or a machine in every scene in a factory. Recently,
In the field of process automation, there is an increasing demand for integrated control of control between instrumentation and automation equipment. In order to respond to such a demand, in the conventional device, the control device handles the relationship with the PC as follows. (1) An input relay or the like handled by the PC is assigned to a contact input or the like of the control device, and data of the PC is read into the control device. (2) An output relay or the like handled by the PC is assigned to a contact output or the like of the control device, and data of the control device is written on the PC side.

[0003]

However, in the conventional device handled in this way, when the power of the control device is interrupted or when the communication between the control device and the PC is interrupted, the reading / writing of data from the control device is interrupted. However, the PC side has a problem that data discrepancy occurs between the control device and the PC because the control is continued. FIG. 4 is a conceptual diagram showing an operation in a case where data of a control device is written to a PC in a conventional device. At time T1, the control device is PC
It is assumed that a power failure has occurred in the control device after data has been written to the controller. The PC continues the control based on the data written at time T1, and the data on the PC is updated according to the control. When the power failure of the control device is restored, the control device writes the data before the power failure (or before the interruption of communication) to the PC again at time T2. By this write operation, the updated data on the PC side is changed (overwritten) to the data sent from the control device side. For this reason, the output of the PC suddenly changes, and the continuity of control is impaired. SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and when connecting a control device to a PC, integrating instrumentation and electric control, and performing unified management by a distributed control device,
An object of the present invention is to provide a distributed control device in which the output of a PC does not change suddenly at the start of communication between C and a control device, and thus can maintain control continuity.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention connects a control device to a programmable controller (PC), integrates instrumentation and electric machine control, and unifies and manages them. A control device, comprising: an internal instrument having a control function; a communication means for communicating with the PC; and a communication status monitoring means for monitoring a communication status between the PC and the control device. When the communication status monitoring means detects resumption of communication between the PC and the control device, a PC data storage means for reading data on the PC side via the communication means and storing the data, A distributed control apparatus, further comprising an in-PC data reflecting unit that matches an output value with PC data stored in the PC data storage unit.

[0005]

When communication is resumed after communication between the PC and the control device has been interrupted due to a power outage or a communication failure of the control device, the communication status monitoring means detects this. The PC data storage means reads the latest data from the PC and stores it in response to the restart of communication. The data reflection means in the PC corrects the output value which the internal meter is going to output so as to match the data stored in the PC data storage means. Thereby, the continuity of the control can be maintained even after the communication is restarted.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration block diagram showing one embodiment of the present invention. In the figure, OP is an operator station that functions as a man-machine interface, and is provided with display means such as a CRT for displaying various information, and a keyboard and a pointing device for inputting data and operating and operating processes. ing. CS is a control device connected to the operator station OP via a communication line, and a plurality of CSs are provided according to the scale of the process. Are a plurality of programmable controllers (PCs) connected to the control device CS, each having a common register 10, and the control device CS
The contents of the common register can be rewritten or read.

In the control unit CS, reference numeral 21 denotes a plurality of internal instruments having a control function, such as an instrument having a feedback control function for controlling a process, an instrument having a sequence control function suitable for controlling various electric appliances, and a switch. There are instruments and the like having functions, and a system suitable for various processes can be configured by appropriately connecting these internal instruments. 22, communication means for communicating with the operator station OP on the upper side;
Communication means for communicating with the communication terminals 11, 12,.
Data can be transmitted and received in a standardized communication format such as S232C. 24 is each PC11,12
And a communication status monitoring means for monitoring a communication status between the control device CS and the communication device. The communication status monitoring means monitors whether communication is normally performed, whether normal communication is resumed, and the like. 25, the communication status monitoring means 24 detects the restart of communication between each of the PCs 11, 12,.
A data storage means in the PC for reading the data on the C side and storing the data, and 26 stores the data read from the PC side.
This is a definition information storage unit that defines where to store the data in the PC data storage unit 25. 27 is a PC data reflection means for correcting the internal instrument data so that the output value of the internal instrument 21 matches the PC data stored in the PC data storage means 25, and 28 is handled by the internal instrument 21 A database built from various signals (data)
In addition to being accessible from the operator station OP, the data output from each internal instrument can be modified by the data reflection means 27 in the PC.

[0008] The operation of the apparatus thus constructed will be described below. Each internal instrument 21 in the control device CS has its input assigned to a specific contact signal or analog signal such as an input relay handled by the PC in charge of itself, and also outputs the output of the PC in charge of itself. Specific output signals such as coils are assigned respectively. Electrical equipment such as input / output relays are connected to each PC, and their control states (relay states and the like) are written in the common register 10. When the communication between the control device CS and each PC is normal, the control device CS reads the relay state and the like handled by the PC via the common register 10 and writes the output. As a result, the control device CS
The input / output states of various electric devices handled by C can be handled as if they were input / output signals to the user, and these can be controlled.

The various data handled by the internal instrument 21 in the control device CS is constructed as a database, so that the PC
Can be uniformly managed in the operator station OP. FIG. 2 is a flowchart illustrating an operation in a case where the power supply of the control device CS is interrupted or a case where communication with the PC is interrupted. The communication state monitoring means 24 includes the control device CS
Of the control device CS and all the PCs are resumed (steps 1 and 2).
Step 2). When the communication state is resumed, the latest data of each PC (these data is written in the respective common registers) is collected by the data storage means 25 in the PC via the communication means 23, and the data is stored in the data storage means 25. The data is stored in accordance with the data definition in the PC stored in the definition information storage unit 26. Next, the data reflection means 27 in the PC corrects the output value of each internal instrument so as to match the value of the output (data) in the PC in charge of the internal instrument (steps 3 and 4).

FIG. 3 is a conceptual diagram showing the operation of the apparatus of the present invention when data of the control device CS is written to the PC. Assume that a power failure occurs in the control device after the control device writes data to the PC at time T1. The PC continues the control based on the data written at time T1, and the data on the PC is updated according to the control. When the power failure of the control device CS is restored, the control device:
First, when communication is resumed at time T2, the PC
After reading the internal data through the communication means 23 and reflecting the data in the PC on the output value of the internal meter in the control device, and matching the data on the control device side with the data on the PC side, the control device C
The control result obtained in S is written on the PC side. In this way, after the data in the PC is reflected on the output values of all the internal instruments that are sending output to the PC, the control returns to the normal control state. At this time, the control device CS
The output value of each internal instrument in P
Since the data is corrected to match the data in C, the output of each PC can maintain control continuity without abrupt changes. In the above embodiment, the database, the data storage unit in the PC, and the data definition information storage unit in the PC are shown in separate blocks. However, these functional areas may be allocated to one memory.

[0011]

As described above in detail, according to the present invention, when the control device and the PC are connected, the instrumentation and the electric machine control are integrated, and the decentralized control device performs unified management. When the communication between the PC and the control device is restarted, a distributed control device can be realized in which the output of the PC does not change abruptly, and thus can maintain the continuity of control.

[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 in a case where a power supply of a control device CS is interrupted or a case where communication with a PC is interrupted.

FIG. 3 is a conceptual diagram showing an operation when data of a control device CS is written to a PC side in the device of the present invention.

FIG. 4 is a conceptual diagram showing an operation when writing data of a control device to a PC in a conventional device.

[Explanation of symbols]

OP Operator station CS control device 11, 12, 13 ... Programmable controller (PC) 10 Common register 21 Plurality of internal instruments 22 Communication means 23 Communication means 24 Communication status monitoring means 25 PC data storage means 26 Definition information storage 27 PC Internal data reflection means 28 database

Claims (1)

(57) [Claims] 1. A distributed control device for connecting a control device and a programmable controller (PC), integrating instrumentation and electric machine control and integrally managing them, wherein the control device has a control function. A communication device for communicating between the PC and the control device; a communication status monitoring device for monitoring a communication status between the PC and the control device; and a communication status monitoring device for controlling communication between the PC and the control device. When the communication restart is detected, PC data storage means for reading the data on the PC side via the communication means and storing the data, and PC data stored in the PC data storage means for the output value of the internal meter. And a data reflecting means in the PC for matching the data.