Rs-485 Communications Connections - Ametek Thermox Series 2000 WDG-IV User Manual

3-34 | Thermox Series 2000 WDG-IV / IVC / IVCM
Digital input to initiate remote calibration unit
The digital input connections on the wiring card allow you to initiate a
remote calibration from a location other than the control unit (see Figure
3-23). For this option to work, you must have a remote calibration unit
and an auto calibration card. The system monitors the digital input, and
when the switch closes, it sends the system into an automatic calibration.
The switch you connect to this digital input must be a normally open switch.
Digital input connections are labeled as follows on the wiring card:
DIGIN +
DIGIN -

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 inter-
face.
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
3-24). 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)