Applies To:
  • CitectSCADA x.x
Summary:
Using TCP/IP in WFW3.11 for Citect LAN communication over multiple subnetworks without a WINS or DHCP server. How do I get this working? 

Solution:
Edit the WFW file 'lmhosts' by entering the TCP/IP address and NETBIOS names as per the files internal documentation. For each machine it is necessary to add in the Citect server addresses that the machine will connect to. To do this enter each servers machine name, and any other service names such as Trend, Alarm, etc. It is also necessary to add an entry for the default gateway despite having already entered this in the TCP/IP setup. For best response it is advisable to enter only the addresses of machines that will be connected to, delete all the comment fields at the top of 'lmhosts', and preload the names to cache using the #PRE extension.

Example:
For a display node which is to connect to a Citect IO, alarm, report, and trend server. Where the servers Windows name is CtServ1, the IO server name (from the Citect database is IOServer1, and the server name is Citect1.

200.200.30.101 CtServ1        #PRE
200.200.30.101 IOServer1      #PRE
200.200.30.101 Citect1Alarm   #PRE
200.200.30.101 Citect1Report  #PRE
200.200.30.101 Citect1Trend   #PRE
200.200.30.125 DefaultGateway #PRE

Note: The LMHost entries need only include machines which are on an other subnet. This is because the TCP/IP driver isues a b-node request (i.e. broadcast requsting the IP address given the NETBIOS name) within the subnet.

The nbtstat utility can be used to re-load the LMHosts file into cache without re-starting Windows. ie

nbtstat -R reloads the remote cache name table
nbtstat -r lists the contents of the cache

 
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