Chemical DCS Network Based on OPC Protocol

OPC (OLEfor Process Control) is an industry standard based on Microsoft's OLE (now ActiveX), COM, and DCOM technologies. It includes a comprehensive set of interfaces, properties, and methods for process control and manufacturing automation systems. OPC adopts the client/server model. Most SCADA software and DCS systems provide OPC server (an application program). As shown in the figure, OPC can be regarded as "software bus" in the measurement and control network.

For the DCS Networking System (referred to as DCS Network) working group named ZH-HDCS, all machines in the network are members of the working group. The factory also requires the DCS network as a subnet of the enterprise network to provide interface management data to the enterprise, as shown in the network structure.

Rent 5 software 10PC server A110PC server B 11OPC server cl application and multi-OPC server communication Many industrial enterprises have installed DCS system, due to process, performance, price and other reasons, often in a company with multiple manufacturers of DCS, It is not an easy task to connect these different manufacturers and systems with different technical standards into a network. This article through an example, describes the use of OPC technology to connect DCS into a network, and then exchange data with enterprise-class information systems.

2 Network Structure Zhuzhou Chemical Group owns DCS systems from multiple manufacturers and requires that some of the DCS's important real-time data (approximately 1800) be sent to the meter control center, plant control room, and other related departments. The curve forms dynamically display these temperature, pressure, flow, and other data, and the cumulative output to the report also requires historical curves, alarms and other functions. Make it into a production and dispatching company for the company's production line, and the network structure switch of the hydropower steam DCS networking system is placed on the meter control center. The old aggregation, new aggregation, PVC acetylene from the metering and control center are all about 1000m, with a pair of fiber optic transceivers (multimode, Up to 2000m) connection, energy metering system and Core-View configuration software machine are placed in the nearby office building, within 100m, twisted pair connection is sufficient. At the old aggregation site, a gateway equipped with an OPC server is placed, two network cards are inserted, one is connected to the old aggregate DCS system and the hydrazine DCS system, and one is connected to the DCS network.

In the new aggregation department, a machine equipped with an OPC service program is selected from the CS-1000, two network cards are interpolated, one is connected to the CS-1000 system, and one is connected to the DCS network. PVC acetylene is the same as the new polymerization. The energy metering system consists of ADAM modules, OPC, and CoreView DCS systems. There is only one computer in the system, and one network card is used to connect to the DCS network. The CorsView configuration software provides OPC support and has network capabilities. The foundation and sources of CoreView, material metering, and cost assessment are installed in the DCS network. The entire I project that the chemical automation and instrument configuration software on the computer can be transferred to the DCS real-time data; In addition to the computer is equipped with ODBC, collected from the various DCS system data are regularly transmitted to the management software.

Because the new polymerization and PVC acetylene are two independent DCS, the machine name with OPC server is exactly the same and all are HIS0124. Now connect to DCS network. During system installation, stop PVC acetylene and modify its machine name as HIS0224. Install the operating system Windows2000Profession and Windows2000Server, install two network cards is very convenient. The IP addresses of the two network cards of all machines must not be in one network segment.

After the successful registration of the 3OPC interface registration network, complete the software configuration in three steps: register the OPC interface on the client (here ADCS2 receives the OPC server data); configure the DCOM to have access to the remote OPC server; configure Configuration software or self-developed monitoring software OPC parameters.

According to the principle of COM, we need to use scheduling to access remote data. As shown, the client requests data from the COM server during the client's use of the proxy object for scheduling. The proxy object provides the same interface to the COM service program but does not implement the COM service program method. It only wraps the parameters and passes the data packet to the actual COM service program. Then, the method returns the result from the COM service program. When you open a packet, interpret the response data.

COM Scheduling Principles of COM COM scheduling includes: type library scheduling, standard scheduling, and custom scheduling. All DCS networks use standard scheduling. The file containing the proxy/stub module (the program with the suffix DLL) should be inserted into a floppy disk with the HIS0224).

After the installation is complete, two OPC server names are observed in the "Applications" property page of the "Distributed COM Configuration Properties": Custom interfaces are used on the DCS network, and automation interfaces are applications developed for languages ​​such as Visual Basic. . All OPC servers provide custom interfaces, but most do not provide automation interfaces.

The client installs the OPC library. These library files contain the OPC interface library files and some standard OPC library files. The specific process is as follows: b. Select the custom installation during the "Set Type" step.

c. Select the OPC service during the "Select part" step, and leave nothing else.

After the installation is complete, the OPC server name can be observed: Custom connection (3) Energy metering DCS, Advantech ADAM modules and Advantech OPC installation Please refer to the related product operation manual. ADAM is very easy to use, but do not set CheckSum. I purchased Advantech OPC. Server does not support this feature and it took a long time to discover this defect. Advantech's OPC and CoreView DCS systems are installed on the same machine and belong to the local server. After the CoreView DCS system obtains data, the CoreView configuration software uses the TCPP protocol to transfer data directly. In this way, the client does not need to register the OPC interface, does not need to configure the related DCOM. It exists on the client and server, and both are registered to the registry. According to the above-mentioned COM scheduling principle, to access the OPC server, the client needs to register with the OPC interface and install an executable program that executes the OPC interface. Below we describe the installation steps of the OPC interface of the three types of DCS.

DCOM is a high-level network protocol that enables COM-based components to collaborate between two processes on different machines. DCOM allows programmers not to write network code to handle the communication required for distributed components to interact across the network.

Pieces, these library files contain the OPC interface library files and some standard DCS network DCOM configuration as follows: OPC library files. The specific operation process is as follows: (1) The default attribute.

1a. On a machine with Yokogawa 0PC server 124 or a. Select: Enable distributed He Haijiang etc. on this computer. Chemical DCS network users based on OPC protocol, permission to access.

C. Default configuration permissions. Add and register: Everyone's users have full control of permissions.

Generally add connection-oriented TCP/IP This protocol can coexist and share, and then add a tunnel TCP/IP protocol, which is conducive to the connection of the virtual network.

The above configuration is for all components, we can also configure the properties of each component (all OPC servers are components), and the latter can cover the former. Here take the new aggregation (machine name HIS0124) as an example, ADCS2 as a client receives data from the HIS0124.

Find the OPC server name Yokogawa.CSHISOPC in the aforementioned "Applications" property page. When selected, the "Properties dialog box opens. Five property pages appear: General, Location, Security, Identity, Endpoint. Lists server and client property page settings.

b. Location: Run the application on the following computer to fill in the ADCS2. a General: Authentication level "Default".

b. Location: Run the application on the following computer to fill in HIS0124. 5 Software Technology Server: Convert machine has new object information MULTI-QIqi;//MFC structure, pass newly created object return interface pointer *//Can't connect Remote OPC server returnFALSE ;// Returned interface pointer // Takes to the IOPCServer interface Can then operate on objects that have been created on the remote machine.