OPC is a standard programming interface that allows Windows software to interact with industrial hardware. OPC server is Implemented in Server/ client pair.
OPC Server is software that converts the hardware communication protocol used by PLC into the OPC protocol. OPC client software is any software that needs to interact with hardware, such as HMI . An OPC client uses an OPC server to receive data or send commands from the device.
The value of OPC is that it is an open standard, which means lower costs for manufacturers and more choices for consumers. Device manufacturers need to provide only one OPC server for their devices to communicate with any OPC client. Software vendors easily integrate OPC client capabilities into their products and sync instantly with thousands of devices.
Users can choose which OPC client software they need, and be assured that their OPC-powered devices, and vice versa, will communicate smoothly. A typical OPC connection scenario is the same client-to-server connection on a PC as described above, but there are more possibilities. For example, you might need:
Connect the OPC client to multiple OPC servers. This is called the OPC Assembly.
Connect the OPC server to the OPC server on a network. This can be done using an OPC tunnel.
Connect the OPC server to another OPC server for data sharing. This is known as the OPC Bridge.