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

What would cause a Socket Connection Refused hardware alarm on Citect I/O Servers? The servers appear to be working properly as far as displaying data and supporting redundancy.  

A related problem is found in Microsoft Knowledge Base article Q245678
. Winsock calls may not work properly after applying Windows NT 4.0 service pack 6. Generally the problem manifests itself when a program attempts to connect to the server. Windows NT 4 Service Pack 6a has been released to fix this problem.

In this instance, the user found a display client with a bad network connector. The display client was able to send messages to, but was unable to receive messages from the server. This resulted in the 'I/O Server Socket Connection Refused' error. Removing and fixing the display client resolved the problem.