Applies To:
  • CitectSCADA 5.xx


This article has been superseded by article Q4627  - 'A Client/Server Connection is not Re-established after a Network Failure on Windows 2000/XP'.

A client/server connection is not re-established after a network failure when using NetBIOS over TCP/IP on Win2000 machines.

This will occur if a Win2000 machine being used as a display client or I/O Server has its network cable removed, all display values on the client or any client scanning the I/O Server will display #COM due to the broken connection, however when the network cable is replaced these display values will remain in the #COM state. Citect on the machine that has had its network cable removed must be restarted before data will be displayed again.

This situation is reported to the syslog with the message, "Invalid adapter number error. Disable Win2000 Media sensing".


This problem is specific to Win2000 machines using TCP/IP and is due to the Win2000 "Media Sensing" feature.

To correct this problem, disable the media sensing in the following manner,

1. From the start menu select Run, and open Regedt32.exe.

2. Use the Registry Editor to view the following key in the registry:


Add the following registry values:

    Value Name: DisableDHCPMediaSense
    Data Type: REG_DWORD -Boolean
    Value: 1

3. Restart the computer.