Communications Connections - Ametek Thermox WDG Insitu User Manual

3-26 | Thermox Series 2000 WDG Insitu Analyzer
Rs-485 Communications Connections
The Series 2000 control unit has the ability to communicate with other computers
that use the same protocol and have the same hardware interface. See the Serial
Communication Appendix for information on the RS-485 serial communications
protocol.
2-wire connections
The connections used for RS-485 2-wire communications on the wiring card are
labeled as follows:
4WTX+/2W+
4WTX-/2W-
Connect all the 2-wire pluses (+) and all the 2-wire minuses (-) in parallel with
all the devices in a daisy-chain fashion, including all the control units on the
network and the host computer. In addition, on the host computer connect the
receive and transmit terminal block connections (see Figure 3-23W). Be sure to
use twisted-pair cable for all connections.
2-wire termination resistor
The Series 2000 control unit is equipped with a termination resistor that can be
used for the last control unit on the network. Switch 3 on SW1 of the display
module allows you to place a 120 ohm termination resistor into the RS-485 cir-
cuit:
Switch 3 of SW1 = ON (Termination Resistor In Circuit)