Applies To:
  • CitectSCADA 5.41, 5.41 Service Pack A, 5.41 Service Pack B, 5.42
  • CitectHMI 5.41, 5.41 Service Pack A, 5.41 Service Pack B, 5.42

From Citect v 5.41 a timeout for TCP/IP socket writes was introduced to solve an issue whereby the Win32 API function GetOverlappedResult() could permanently block, refer to Microsoft Windows KB Q138935. This timeout for writing to a socket is set using the 'Citect.ini' parameter '[IPC]SocketSendTimeout' which has a default value of 500 (ms).

For slow TCP/IP connections this timeout may not be long enough, e.g. Radio networks, RAS dialup over GSM, etc. In particular there have been problems reported with receiving Trend data via IDC (Internet Display Client), due to the large size of the Trend data packets.


For slow TCP/IP connections the timeout should be set to a much higher value, say 5 seconds, in the Citect.ini file: