Applies To:
  • CitectSCADA 3.10 3.21 3.30 4.10

My Citect Client (Display Node) seems to have a problem communicating with the IOServer, however on startup all the variables show 0 (zero) straight away without any timeout delay. 

Usually if there is a communication problem, no data will be displayed on the screen on startup or after changing pages until the timeout period has elapsed. In this case the data is being displayed (all zeros) instantly without a timeout, this would indicate that the Client is not requesting any data from the IOServer. This can be caused by having the port name of the IODevice set to "MEMORY" or blank. Some people may assume that the port name is not important if the node is not an IOServer, however if it is blank it will assume MEMORY PLC and all requests for data will go to RAM on the local machine rather than over the network to the IOServer. This problem has been seen when connecting a Windows Client to a Citect for DOS Scanner (old DOS IOServer, no longer available) however it is possible to get this problem with a Windows to Windows configuration. Make sure the port is not blank.