The OPC Comport is associated with one OPC Server. If you have multiple OPC Servers, you must configure an OPC Comport to each Server. All OPC Devices on the same Comport are associated with one OPC Server.
OPC is an acronym for OLE for Process Control. It is an industry standard introduced by Microsoft based on DCOM. The WebAccess Device driver is an OPC Client. Hardware manufactures typically supply an OPC Server to provide access to real-time data. Most OPC Servers allow tags to be "browsed" and "imported". WebAccess provides an OPCTool.exe that allows tags to be "imported" after you have configured an OPC Comport and at least one OPC Device.
The OPC Server software is usually is installed on the SCADA node (a Local OPC Server).
The OPC Server software can also be installed on another PC (a Remote OPC Server) that is not the SCADA Node. A TCP/IP network connection (usually a LAN or Intranet) is used to communicate to the "remote" OPC Server from the SCADA Node. The remote OPC Server must have either WebAccess Project Node software or OPC Service installed.
Figure 14.4 OPC Comport properties