Series 2000 Communications Handbook - Soliton

Digital Communications HardwareSeries 2000 Communications Handbook2.9. WIRING 2-WIRE485To use RS485, buffer the RS232 port of the PC with a suitable RS232/RS485 converter. TheKD485 Communications Adapter unit is recommended for this purpose. The use of a RS485board built into the computer is not recommended since this board is unlikely to be isolated,which may cause noise problems, and the Rx terminals are unlikely to be biased correctly forthis application.To construct a cable for RS485 operation use a screened cable with one (RS485) twisted pairplus a separate core for common. Although common or screen connections are not necessary,their use will significantly improve noise immunity.The terminals used for RS485 digital communications are listed in the table below.StandardCable ColourPC socket pinno. 25 wayPC Function * Instrument Terminal InstrumentFunctionWhite 3 Receive (RX+) HF (B) or (B+) Transmit (TX)Black 16 Receive (RX-)Red 12 Transmit (TX+) HE (A) or (A+) Receive (RX)Black 13 Transmit (TX-)Green 7 Common HD CommonScreen 1 Ground* These are the functions normally assigned to socket pins. Please check your PC manual toconfirm .2-10 Series 2000 Communications Handbook Part No HA026230 Issue 2.0 Feb-00