HI all,
Agree with Roberts comment re termination resistor etc.
I used RS-485 as the underlying comms protocol for the theatrical DMX-512 system.
See this post re testing etc - it also contains links to other doco about RS-485
You need to have the individual devices respond to individual addresses if sending info, or have some end-to-end protocol to allow devices to receive / respond to appropriate commands if you are expecting them to provide data back to a central point. Note RS-485 is not really suitable for ethernet-style Carrier sense / collision detection modes
Murray
