Citect will only wait a given time whilst trying to send TCP/IP data. This time is configurable using the [IPC]SocketSendTimeout INI parameter on the IOServer. If this time is exceeded, the connection is dropped. The default for this parameter is 500ms, but this may be insufficient on busy networks and should be increased accordingly.

In addition, you should set this in the Windows registry for your CTAPI client application as follows:

1. Add this registry Key

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters

DefaultSendWindow

2. Set it's original value to dword:FC00 (hex), and increase this value until the problem no longer occurs. A reboot is required to cause the change to take effect.

NB: Setting either of these values too high may result in performance degradation if connections are actually unavailable, as the IOServer will take longer to reset when a connection is dropped.