If the Trex unit is connected to an externally-powered HART transmitter, the device
connection wizard prompts you if you want to increase loop resistance. The Trex unit then
selects the 250 Ohm or 500 Ohm resistor; you cannot select a specific value. The selected
resistor value is not displayed on the screen.
Procedure
1. If you want the Trex unit to power a 2-wire HART transmitter, do the following:
a. Connect the lead set to the HART + pwr terminals on the Trex unit and to the
communication terminals on the device.
Connection for providing power to a 2-wire HART transmitterFigure 3-27:
b. In the Field Communicator application, tap HART.
c. Tap Yes when asked if you intend to provide power.
d. Tap Transmitter. The Trex unit applies the internal resistor.
e. Follow any additional prompts to connect to the device.
2. If the Trex unit is connected to an externally-powered 2-wire HART transmitter, do
the following:
a. Connect the lead set to the HART terminals on the Trex unit and to the
communication terminals on the device in-series. (If you are connecting to a 4-
wire transmitter, connect the Trex unit in parallel.)
Field Communicator application
User Guide 77
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