Applies To:
  • CitectSCADA 5.xx
  • CitectHMI 5.xx

The problem will occur on systems configured with the following:

- TCP/IP sockets used for Citect Client/Server networking - ie [LAN] TCPIP=1

- an I/O Server with a name that contains the word 'Alarm', 'Trend' or 'Report'

The system may fail at startup or may run correctly for a long period of time and then fail unexpectedly, usually after a network dropout. A hardware alarm of 'IOServer Socket Connection refused' may be shown on the client.

Once the failure has occurred the affected server needs to be restarted before clients can communicate with it successfully again.

Rename your I/O Server so it does not contain the text 'Alarm', 'Trend' or 'Report'.

Consider calling the I/O Server on the Alarm Server "IOALM" rather than "IOALARM".

Citect version 5.42 and later will warn you at startup if you have an invalid I/O Server name, with the following message:

Invalid I/O Server name 'Alarm'.

Cannot contain reserved words 'Alarm', 'Trend' or 'Report'.