Applies To:
  • CitectSCADA
Summary:

Note:
This article has been superseded by article Q4627  - 'A Client/Server Connection is not Re-established after a Network Failure on Windows 2000/XP'.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 it's 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 it's network cable removed must be restarted before data will be displayed again.

 

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

To correct this problem Citect automatically disables the Media Sensing feature when installed on a Win2000 machine.

The Media Sensing feature can be re-enabled 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:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters

Remove the following registry value:

Value Name: DisableDHCPMediaSense

3. Restart the computer.

WARNING  Re-enabling this feature when using NetBIOS over TCP/IP on a Win2000 machine will prevent Citect being able to re-establish a network connection after a network failure. Citect will have to be restarted on a machine that loses it's network connection.

 
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