Hi! Thank all the people who has answerd my question. After a visit of the Maxim site i've decide to use RS-485 using the MAX487. It really more simple to use a IC and a popual bus system as redevelop the wheel a second time. Thank you again for your suggestions and pointing me a direction. cu, Christian -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads