Modbus mapping and Quantum PLC

I am looking to connect a Quantum PLC to some controllers via Modbus TCP/IP. The controller data mapping document shows one of the registers I am interested in is 41001. Does this mean that by default I need to be looking at %IW1001 in the PLC? I think I am looking in the right area of Unity Pro, the Communications tab/Networks, I believe I need to configure something here. Any advice appreciated.

40000 registers are the same as %MW, 41001 should be in %MW1001
I say 'should' because it depends on the plc and drivers etc, it could be in %MW1000. %MW is normally 0 based while 40000 style is 1 based

hope this helps