OPC (OLE for Process Control) is a set of open standards communication specifications intended for the industrial automation industry. OPC provides a common way for applications to access data from sources such as PLCs and databases.
The specifications are maintained by the OPC Foundation and are reviewed constantly to verify that they meet the needs of industry. The OPC Foundation's goal is to promote interoperability (open connectivity) through the use of open standards. CitectSCADA runtime implements vDA2.05 of the OPC specifications. For details on the OPC specifications, navigate to www.opcfoundation.org.
When an OPC Server is used to collect data from physical equipment in a plant, any OPC Client can access data directly from the OPC Server, as shown below: