Hi I have a FX1N and I would like to know if you can MODBUS to it via the on board programing port I am a bit confused as everything I have read so far about modbus on a FX1n says to add an rs232 or rs485 expansion board this to me seems strange when you can already read and write to the plc via the programing port so why would I need to add an extra port. I am talking to this unit with a usb rs232 to rs485 adapter via the programing port. Thanks.