When communicating using Modbus Plus, request packets may have to be routed across various BP85 Bridge Plus devices to reach the intended PLC. The routing information is stored as part of the PLC address.
Because VTScada workstations that are located on different subnets will have to be routed through intervening BP85 Bridge Plus devices, it is therefore necessary that the PLC address of the Modbus Compatible Device tag to be resolved based on the workstation the tag is running on.
The expression to use for the PLC address of PLC (x) in the above example might be as follows:
ToUpper(RPCManager\WkStnName) == "SERVER_B" ? "20.10" : "10"
This code says that, if the address is being resolved from server B, then use "20.10" otherwise use "10". The following illustration shows how this would look in your tag configuration panel.
