Applies To:
  • CitectSCADA 6..x, v7.x
  • VijeoCitect v7.x
  • PowerLogic SCADA v7.x

Initial connection to the OPC server and getting GOOD Quality.

When an OPC client connects to the Citect Remote OPC server, it will launch the ctOPC32.exe (Citect.OPCRemote) or load the ctOPC32.dll (Citect.OPC) application. If the item names are already known, the items can be added and activated without the need to browse.

However, OPC items can only be activated when the SCADA Runtime is up and running. If the SCADA Runtime is not yet ready, the activation will fail. The Citect OPC server will not re-attempt to activate the tags unless requested by the OPC client.

An OPC client should therefore be able to activate items on demand, ie in this case, as soon as the SCADA Runtime becomes available. The latter can be checked via, for example a telnet into TCP port 2073 (which is the port that the OPC server uses to connect to the SCADA runtime).


If the SCADA Runtime goes down

Quality for all OPC items will go to BAD Quality. However, these items will still be active on the OPC client side. Therefore, when the SCADA runtime comes online again, the quality should become GOOD again, without intervention from the OPC client.


OPC redundancy

If you wish to set up OPC redundancy, ie switch to a backup OPC server when the Primary is reporting BAD quality, then we recommend that you pick a couple of OPC items as “status items”. As soon as one of these status items goes to BAD/UNCERTAIN quality, a switch over could be forced from the OPC client.

 OPC server, ctOPC, GOOD, BAD, Quality, Remote