Applies To:
  • CitectSCADA
  • CitectHMI

I am running the latest version of CitectSCADA on an up-to-date Win2000 machine. Immediately after starting up my project, I get the following NetBIOS error:

"Cannot Reset NetBIOS, Error 35"

What is causing this error and how can I resolve it?


The NetBIOS driver may need to be re-installed, but this NetBIOS error is commonly a result of failing to enable NetBIOS over TCP/IP. In Win2000 you have the option to enable or disable NetBIOS over TCP/IP (NBT). To enable this option, please perform the following:

    Right-click on My Network Places and select Properties

    Right-click on the appropriate Local Area Connection icon and select Properties

    Select Internet Protocol (TCP/IP) and click the Properties button

    Click the Advanced button and select the WINS tab

    Select Enable NetBIOS over TCP/IP radio button

This change will take effect immediately without having to reboot the system. From now on I will refer to the "Client" as the computer from where you map drives and other shared resources, and to the "Server" as the computer with resources that are shared:

If the Client has NBT enabled, it will always try to connect to the Server at both ports 139 and 445 simultaneously. If there is a response from port 445, it sends an RST (Reset for TCP Packet) to port 139, and continues its SMB (Server Message Block) session to port 445 only. If there is no response from port 445, it will continue its SMB session to port 139 only, if it gets a response from there. If there is no response from either of the ports, the session will fail completely.

If the Client has NBT disabled, it will always try to connect to the Server at port 445 only. If the Server answers on port 445, the session will be established and continue on that port. If it doesn't answer, the session will fail completely.

If the Server has NBT enabled, it listens on UDP ports 137,138 and on TCP ports 139, 445. If it has NBT disabled, it listens on TCP port 445 only.

If using multiple network cards, another matter to consider is whether or not the correct LANa number(s) is/are being referenced for the [LAN]LANa parameter in your CITECT.INI file. This parameter defines the protocol stack that CitectSCADA uses for NetBIOS communications and is set to -1 by default. "-1" tells CitectSCADA to automatically search and use all available NetBIOS LANa on the computer. However, this does not mean that CitectSCADA will necessarily use the LANa from the correct network card. To view which LANa numbers (from 0 to 31) are actually being used for each network card, you can use the LANACFG.EXE utility from Microsoft (which can also be downloaded from the Citect Toolbox) and then set the [LAN]LANa parameter to equal the appropriate LANa number(s). For example:

LANa = 0,3,7


Windows 2000, Local Area Network, LAN Adapter