Technical Notes: OPC (Open Process Control)

The Benefits of OPC

When data acquisition devices conform to the OPC standard, you can use them with any OPC-enabled software application. And vice versa. You can therefore easily combine different devices from different manufacturers in one system, without the normal integration headaches. OPC gives you the freedom to add new hardware from third-party vendors to existing set-ups, or to replace a device, without worrying about compatibility with your chosen software. Select exactly the hardware and software you want for a particular application.

Based on Microsoft Windows technology, OPC now stands for Open Process Control. Previously it stood for OLE Process Control but today the OLE technology has been replaced by Active X.

The measurement and control hardware (such as a Microlink) provides front-line data acquisition. As soon as the hardware device has collected the data it makes it available to software applications running under Windows. It presents the data according to the OPC standard, and is thus known as an OPC server. Each OPC server offers data in the same way. If the software application can understand the OPC format it can therefore access data from any OPC server device, making individual drivers for each piece of equipment obsolete.

OPC-enabled software include spreadsheets, databases, virtual instruments and SCADA (supervisory control and data acquisition) interfaces. These applications are known as OPC client software. You can also develop your own Visual Basic programs to exchange data with OPC servers. Your program will work with all OPC devices connected to your PC and on the network.

Each OPC server can simultaneously provide data for any number of OPC clients. Likewise multiple clients can at the same moment access any server: a robust method of communication. With OPC, measurement and control systems can share information and co-operate with other installations across factories, offices, laboratories, etc. The same data is therefore readily available to engineering, maintenance, fact to anyone that requires up-to-the-minute data on which to base their decisions.

OPC allows "plug-and-play". All OPC devices will connect together and immediately work with the OPC client software. This has the potential to massively reduce installation and system configuration time. It also means that you can add devices without shutting down existing systems.

OPC Summary

  • Combine different devices from different manufacturers in one system
  • Reduce installation time
  • Add devices without stopping existing software and systems
  • Quickly replace a device from one vendor with one from another
  • Share information around networks
  • Device drivers rendered obsolete
  • Factory, laboratory and office applications can all access the same data
  • Reliable data as any number of OPC software applications can simultaneously read a device
  • Single, industry-standard, data interface

Microlink and OPC

All the serial Microlinks can be OPC servers. They offer digital input, output, counters, timers, analogue input and analogue output for monitoring and control of, for example, voltage, current, resistance, temperature, strain, humidity, force, pressure, level, flow, displacement, vibration, speed and concentration. When you purchase the OPC-server software along with the Microlink, you can use them with OPC clients such as Hexatec's Saturn SCADA software and National Instruments' LabVIEW.

Microlink 3000 OPC Server

Microlink 3000 Series

A frame-based system into which you place the modules of your choice. This unrivalled flexibility allows you to connect almost any instrument or transducer to a PC. The Microlink 3000 OPC servers communicate over either RS232 or RS485.

Microlink OPC Server Software

To enable the Microlinks as OPC servers, you need to install on your PC the OPC-server software. This software was written for Biodata by Windmill Software.

For more details of the Microlink OPC Servers contact [email protected].

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