JP4013250B2 - OPC communication station - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In a distributed control system used for large-scale production control and the like, the present invention communicates between various PLCs (programmable controllers) and control systems with different standards (hereinafter sometimes collectively referred to as PLCs) and control systems. It relates to an OPC communication station for performing.
[0002]
[Prior art]
FIG. 3 shows a conventional configuration example for performing communication between a control system and a PLC in a distributed control system used for large-scale production control or the like. When data is exchanged between the control system 11 and the PLC 12, a dedicated PLC communication program 14 is used via a communication IF module 13 mounted on the control controller, such as an RS / Ethernet (registered trademark) communication module. We are communicating.
[0003]
The PLC bus 15 is unique depending on the type of PLC, and the communication protocol also differs depending on the PLC. Therefore, a separate communication IF module 13 and communication program 14 are required for each type of PLC.
[0004]
Data transmitted / received by communication is stored in a buffer (communication input / output area) 17 in an FCS (field control station) 16, and this data can be accessed as a tag from the HIS (human interface station) 18 and functional blocks. .
[0005]
[Non-Patent Document 1]
Automation Vol.43, No.1 (1998-1) P.14-17
[Non-Patent Document 2]
Nikkei Digital Engineering (1998-5) P.126-131
[0006]
[Problems to be solved by the invention]
However, in the prior art, in order to exchange data between the control system 11 and the PLC 12, it is necessary to develop the dedicated communication program 14 and the communication IF module 13 as described above, and the communication means is versatile. There wasn't. Therefore, each time a new PLC is connected to the system, a new development cost is required, and the time lag until communication with the new PLC becomes possible is large.
[0007]
Furthermore, since the dedicated communication program 14 operates only on the FCS 16, the FCS is required even when communication is performed only for the purpose of monitoring, and thus the introduction cost of the communication means is high.
[0008]
In addition, when the data set in the PLC is changed from an external computer, only the changed data cannot be reflected in the PLC.
[0009]
The present invention has been made in view of the above-described problems. Communication with a PLC can be performed universally via an OPC (OLE for Process Control) server, and PLC data can be transmitted to an external computer (FCS). / HIS / high-level computer) can be handled in the same way as general tag access via the control bus, and when the data set in the PLC is changed from an external computer, only the changed data is reflected in the PLC. The purpose is to do.
[0010]
[Means for Solving the Problems]
In the course of various studies, the present inventors have recently provided OPC servers compatible with their own PLCs from various PLC manufacturers, etc., which can be used to reference and set data on the PLC. We paid attention to that As a result of further investigation, communication with various PLCs can be performed universally via an OPC server, and PLC data is transmitted from an external computer (FCS, HIS, host computer, etc.) via a control bus. By implementing an OPC communication station that operates on a general-purpose PC that can be handled in the same way as general tag access and can also monitor PLC data, the above-mentioned problems can be solved. It came.
[0011]
The present invention has been made based on the above consideration, to provide an OPC communication stations of the following (1) to (4).
[0012]
(1) An OPC communication station that exchanges data between a PLC and a control system via an OPC server ,
A communication output means for storing data for setting the collected data and the PLC from the PLC,
A data acquisition means for setting data on the PLC via the OPC server to the communication input means,
Data writing means for making a write request to the OPC server for data set in the PLC stored in the communication input / output means ;
A functional block for referring to and setting data of the PLC by referring to and setting data of the communication input / output means;
Control bus communication means for receiving communication from the control system via a control bus, referring to and setting data of the communication input / output means, and referring to and setting data of the PLC;
An OPC communication station comprising:
[0013]
(2) OPC server communication means for storing setting information to the OPC server necessary for communication with the PLC;
A communication input / output assigning means for storing definition information of mapping between PLC data to be communicated and the communication input / output means;
Configuration changing means for performing processing for communicating and setting the contents of the OPC server communication means and the communication input / output assignment means to the OPC server;
The OPC communication station according to (1), further comprising:
[0014]
(3) The data collection unit receives a change notification from the OPC server for data that has changed on the PLC, and stores only the data on the received PLC in the communication input / output unit by asynchronous reading. The OPC communication station according to (1) or (2).
[0015]
(4) In any one of (1) to (3), the data writing unit makes a write request to the OPC server for data that has changed in the write data in the communication input / output unit. The OPC communication station described.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of the overall configuration of a system using an OPC communication station according to the present invention.
[0020]
In the figure, reference numeral 31 denotes an example of the OPC communication station according to the present invention. The OPC communication station 31 is connected to the OPC server 32 via the Ethernet (registered trademark) 33. The OPC communication station 31 communicates with the OPC server 32 to refer to data of the PLC 34 and set data 35 to the PLC 34.
[0021]
The OPC communication station 31 is connected to the control bus 36, and performs data reference and setting communication 39 on the control bus 36 with the HIS 37, FCS 38, host computer, etc., and data on the PLC 34 from the HIS 37, FCS 38, host computer, etc. Can be referred to and set.
[0022]
The OPC server 32 is connected to the PLC 34 by a unique bus 40 for each PLC 34, and a dedicated IF card 41 corresponding to the unique bus is mounted on the OPC server 32. The OPC server 32 communicates with the PLC 34 according to the setting information and commands from the OPC communication station 31 on the bus 40, and performs data reference and setting 42. The OPC server 32 can also be operated in the same PC as the OPC communication station 31.
[0023]
FIG. 2 shows an internal configuration of the OPC communication station 31 shown in FIG. Communication processing between the OPC communication station 31 and the OPC server 32 is performed using the OLE / DCOM 43.
[0024]
First, the data area constituting the OPC communication station 31 will be described. The communication input / output means 44 is an area for storing data collected from the PLC 34 and storing data to be set in the PLC 34.
[0025]
The OPC server communication unit 45 is an area for storing setting information for the OPC server 32 necessary for communication with the PLC 34. Since the OPC server 32 requires unique setting information for each manufacturer, the OPC server communication means 45 is required.
[0026]
The communication input / output allocation means 46 is an area for storing information defining mapping between PLC data to be communicated and the communication input / output means 44.
[0027]
Next, each processing means constituting the OPC communication station 31 will be described. The function block 47 is a function block for monitoring and processing data. Data setting from the functional block 47 to the PLC 34 is performed by setting data in the communication input / output means 44. When the function block 47 refers to the data from the PLC 34, it is performed by referring to the data of the communication input / output means 44.
[0028]
The control bus communication means 48 receives communication from an external computer 49 (FCS, HIS, host computer, etc.) and refers to or sets the data of the PLC 34. The contents of the processing are the same as in the case of the function block 47, and are performed by referring to and setting data in the communication input / output means 44.
[0029]
The configuration change unit 50 sets the contents of the OPC server communication unit 45 and the communication input / output allocation unit 46 by communicating with the OPC server 32.
[0030]
The data collection unit 51 is a processing unit that sets data on the PLC 34 in the communication input / output unit 44 via the OPC server 32. In actual operation, since a change notification is received from the OPC server 32 for data that has changed on the PLC 34, only the data on the notified PLC is stored in the communication input / output means 44 by asynchronous reading.
[0031]
The data writing means 52 makes a write request to the OPC server 32 for data that has changed in the write data in the communication input / output means 44.
[0032]
In the OPC communication station of the present embodiment, means for communicating with the PLC via the OPC server is constituted by data collection means 51 and data writing means 52. The means for communicating with the external computer via the control bus is constituted by a control bus communication means 48. The means for accessing the PLC data as a tag is constituted by the control bus communication means 48. The means for monitoring the PLC data is constituted by a function block 47.
[0033]
As described above, the OPC communication station of this embodiment has the following advantages.
(A) It is possible to perform general-purpose data exchange with the PLC by connecting to commercially available OPC servers from different manufacturers. Further, communication with various PLCs can be performed only by changing the OPC server. Therefore, it is not necessary to develop a communication program and a communication IF card even for a PLC to be newly communicated, and connection to the PLC is possible without a development time lag.
[0034]
(B) Since the data to be communicated can be accessed via the control bus of the distributed control system, it is possible to refer to and set the PLC data from the control controller (FCS), the operation monitoring function (HIS), and the host computer. . In addition, access to PLC data can be handled in the same manner as a tag of a distributed control system, so that an application can be easily constructed.
[0035]
(C) Since the functional block can operate in the communication station, processing such as data monitoring, trend collection, alarm generation, and data processing can be performed in the communication station.
[0036]
(D) Except for the communication card with the control bus, no dedicated hardware is required, and it can operate on a general-purpose PC.
[0037]
(E) Since a write request is made to the OPC server for data that has changed in the write data in the communication input / output means, only the changed data can be reflected in the PLC when the data set in the PLC is changed from an external computer.
[0038]
【The invention's effect】
According to the OPC communication station of the present invention, it is possible to perform communication with a PLC via an OPC server for general purposes, and handle PLC data from an external computer via a control bus in the same way as general tag access. In addition, when the data set in the PLC is changed from an external computer, only the changed data can be reflected in the PLC.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of the overall configuration of a system using an OPC communication station according to the present invention.
FIG. 2 is a diagram showing an internal configuration of the OPC communication station in FIG. 1;
FIG. 3 is a diagram illustrating a configuration example of a conventional system for performing communication between a control system and a PLC in a distributed control system.
[Explanation of symbols]
31 OPC communication station 32 OPC server 34 PLC
36 Control bus 37 HIS
38 FCS
44 Communication input / output means 45 OPC server communication means 46 Communication input / output allocation means 47 Function block 48 Control bus communication means 51 Data collection means 52 Data writing means

Claims (4)

An OPC communication station that exchanges data between the PLC and the control system via an OPC server ,
A communication output means for storing data for setting the collected data and the PLC from the PLC,
A data acquisition means for setting data on the PLC via the OPC server to the communication input means,
Data writing means for making a write request to the OPC server for data set in the PLC stored in the communication input / output means ;
A functional block for referring to and setting data of the PLC by referring to and setting data of the communication input / output means;
Control bus communication means for receiving communication via a control bus from the control system and referring to and setting data of the communication input / output means to refer to and set data of the PLC;
An OPC communication station comprising: OPC server communication means for storing setting information to the OPC server necessary for communication with the PLC;
Communication input / output allocation means for storing definition information of mapping between PLC data to be communicated and the communication input / output means;
Configuration changing means for performing processing for communicating and setting the contents of the OPC server communication means and the communication input / output assignment means to the OPC server;
The OPC communication station according to claim 1, further comprising: The data collection means receives a change notification from the OPC server for data that has changed on the PLC, and stores only the data on the notified PLC in the communication input / output means by asynchronous reading. The OPC communication station according to claim 1 or 2, characterized in that 4. The OPC communication station according to claim 1, wherein the data writing unit makes a write request to the OPC server for data that has changed in the write data in the communication input / output unit. 5. .

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