Technical Specifications Appendix D Cable Drawings - Computer Connection
157
RS-485 Multidrop Cable Connections
1. Install the 120 ohm 1/4 watt terminating resistors externally at the end
points of the cable, on the last instrument in the chain and on the master
computer.
2. The shield of each segment of the cable must be connected to the
ground at one end only.
3. Avoid star or stub connected topologies.
25-pin Computer Connector
RxD
RxD-
TxD-
#32
TxD
120
Shield
TxD-
RxD-
RxD
TxD
RxD-
#2
RxD
TxD-
Shield
#1
TxD
Shield
2
16
CTS-
17
RxD-
TxD-
CTS
RTS-
RTS
120
5
4
15
14
TxD
RxD
3