Title: Hardware Installation Guide.pdf
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 [1219 m]). 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.RS-485 must be terminated at both ends of the RS-485 line (bus). Terminating the line provides a more reliable communication by minimizing the signal reflection and external noise coupling. Each component provided has an on-board terminator. The installer should determine which device is at the end of the communication line.77.3Relay OutputsThe Single Reader SDC Interface Module contains two (2) form-C dry-contact relay outputs, Relay 1 & 2 (K1 & K2). K1 is rated at 5A 30 VDC; K2 is rated at 1A 30 VDC.