Ametek Thermox CEM O2/TM, User Manual

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3-28 | Thermox CEM O2/TM
RS-485 Communications Connections
Follow general grounding and shielding requirements for all wiring
as described in the “General Wiring Requirements” section at the
beginning of this Wiring section.
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 Communications” Appendix in the back of this
manual 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 com-
puter connect the receive and transmit terminal block connections (see
Figure 3-23). 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 circuit:
Switch 3 of SW1 = On (Termination Resistor In Circuit)