OPC is an interface standard developed by a team of 150 companies and is one of the few industrial software standards that seems poised to become a genuine interface standard in our industry. OPC - OLE (object linking and embedding) for process control or more commonly known as open process control due to OLE being slowly replaced by Active X, was primarily used for data acquisition systems and data exchange between reporting systems and sub-systems requiring communication with PLCs, DCSs and scadas.
OPC however, is proving to be an efficient interface between scada systems and PLCs or DCSs allowing the scada developers to reduce their effort in producing and maintaining drivers for all the different industrial controllers. The PLC vendors however have typically left the driver requirements to the scada manufacturers who have had to provide the drivers to communicate with their PLCs. The scada and data historian producers now only have to provide an OPC Client interface with their software and each PLC and DCS vendor must provide an OPC server for each of their products.
Some control system vendors provide both the PLC and the scada software but obviously they do not want to limit their sales with closed systems so they must make their systems open to communication with products from other vendors and OPC fulfils this requirement. Some vendors provide their own OPC interface while others use KEPware as their OPC server often branded with their own name. Likewise other OPC server suppliers supply the KEPware OPC server branded with their name.
KEPware has, over the years, produced OPC server drivers for virtually every control system in production and continue to develop new OPC drivers for new controllers. They also maintain their driver base by continually updating these drivers to include any changes by the PLC manufacturer. The OPC standard is fixed but some OPC server vendors do add tools to the interface to assist the user with configuration of the interface. KEPware includes numerous tools and help facilities to make the interface implementation as easy as possible. KEPware supplies hundreds of interfaces worldwide so they are able to produce the OPC interfaces at around R6000,00 which is often less than half the price of the interfaces supplied by the PLC vendors themselves.
As value adding distributors for KEPware in South Africa, eTX Data Services supplies the interface range and assists with implementations and product licensing. Its pricing is based on the same prices listed on the KEPware site but it offers both end-users and re-sellers respective discounts. Anybody desiring to test their application is invited to download the entire KEPserverEX driver range from the site: www.kepware.com. The interface will run for two hours for testing purposes after-which re-starting the software is necessary to enable the interface to run for another two hours. If unable to download KEPserverEX from the site for any reason, contact ETX Data Services for a product CD to be shipped to you.
ETX Data Services supplies and installs Data Historian-based plant reporting systems, OPC server interfaces, the PI data historian system from OSIsoft and the StJames data historian system. The company also provides training on its systems and various other software systems.
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