By setting the source, you may wish to have the master and slave butterfly valve commands allocated to one relay block. This could be useful if the distance between the upstream and downstream flowmeters is long.
The Preset Multiple Registers will appear. Note that in TCP the 5100 ignores any slave or node identifiers since it is a single device and not acting as a gateway. Set the Modbus register you wish to start changes with and the number of registers to change, up to a maximum of that you are viewing.