OLE for Process Control (OPC™ ) is a technology designed to bridge Windows based applications and process control hardware. It is an open standard that permits a consistent method of accessing field data from plant floor devices. This method remains the same regardless of the type and source of data.
OPC servers provide a method for many different software packages to access data from a process control device, such as a PLC. Traditionally, any time a package needed access to a device’s data, a custom interface, or driver, needed to be written. The purpose of OPC is to define a common interface that is written once, then reused by any business, SCADA, MMI, or customs software packages.
Once an OPC server is written for a particular device, it can be reused by any application that is able to act as an OPC client. OPC servers use Microsoft’s OLE technology (also known as the Common Object Model, or COM) to communicate with clients. COM technology permits a standard for real-time information exchange between software applications and process hardware to be defined.
Sometimes, however, small differences in the interpretation of the OPC specification can lead to problems with interoperability between clients and servers. Even with compliance testing and certification, a number of issues may still arise.
The OPC Sniffer acts as a “data scope” into the communication between OPC clients and servers, outputting a “script” of the activities of both components. The resulting information is invaluable for determining where a problem exists in a non-biased and objective way.
The OPC Sniffer acts as a “data scope” into the communication between OPC clients and servers, outputting a “script” of the activities of both components. The resulting information is invaluable for determining where a problem exists in a non-biased and objective way.
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