Emerson AMS Trex User Manual page 146

Loop Diagnostics application
CAUTION!
Do not add any external power to the device when the Trex unit is powering the device. This
can blow a fuse inside the Trex unit. The repair/replacement will need to be completed at an
authorized service center. Ensure the device is disconnected from the loop/segment and no
other wires are connected to the device before providing power from the Trex unit.
Note
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.
Procedure
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Connect the lead set to the HART + pwr terminals on the Trex unit and to the
transmitter.
Figure 4-15: Connection for providing power to the device
On the Loop Diagnostics screen, tap Trex Unit Power.
Tap Power Transmitter.
The Trex unit uses an internal resistor while powering the device.
Tap OK.
The Trex unit powers the device. The voltage and current measurements are
displayed.
To stop powering the device, do one of the following:
• Tap Trex Unit Power to set the option to Off.
• Tap Exit.
• Remove the lead set from the Trex unit.
User Guide