Title: Hardware Installation Guide.pdf
RS-485 communication is supported for upstream communication only.DDC upstream communication420 — revision 6Hardware Installation GuideTo enable RS-485 termination, install jumper on pin header J33 (on the last unit on the communications line).Notes:The (EIA) Electronic Industries Association standard defines RS-485 as an electrical interface for multi-port communications on a bus transmission line. It allows for high-speed data transfer over extended distances (4000 feet [1219m]). The RS-485 interface uses a balance of differential transmitter/receiver to reject common mode noise. For increased reliability over the extended distances, End-Of-Line (EOL) termination is required.