Emerson AMS Trex Device Communicator User Manual page 131

User Guide
User Guide
1.800.561.8187
Figure 4-3: Select the type of device to power
Power a transmitter
The Trex unit can power one transmitter. When the Trex unit powers a transmitter, an
internal 167 Ohm resistor is used, so an external resistor is not necessary. If you already
connected an external resistor in series with the red or black HART terminal on the Trex
unit, there will be less voltage available for the device, especially at 20 mA. This may cause
the device to power off. The Trex unit begins providing power when you tap OK.
WARNING
Do not insert a resistor in parallel with either the HART + pwr or HART terminals on the
Trex unit or in parallel with the device's communication terminals. This will interfere with
the current measurements.
Power a positioner
The Trex unit can power one positioner and set the current to 4 mA, 20 mA, or another
value between 3.5 and 22.5 mA. This allows you to set the position of the valve. The Trex
unit begins providing power and current when you tap OK.
www.
Loop Diagnostics application
information@itm.com
.com
September 2021
131