Hi,
The best source of information on how to connect a FP-100x in a RS-485 network is its own product manual which can be downloaded at :
http://digital.ni.com/manuals.nsf/webAdvsearch/09D22E8CC0E973C68625678400737AFD?OpenDocument&vid=niwc&node=132100_US
You may also want to look at the following document :
http://digital.ni.com/public.nsf/websearch/7771E92DB978ED7D862568550079CD3A?OpenDocument
Best Regards
Andre Oliveira
