Emerson AMS Trex Device Communicator User Manual page 138

Loop Diagnostics application
September 2021
138
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Figure 4-12: Measure current from an externally-powered transmitter device with
test terminals
The Trex unit measures current from the mA terminals on an externally-powered loop
without breaking the loop and connecting the ammeter (mA terminals) in-series.
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.
Note
Please review your device documentation for additional information about reading current
from the test terminals. The orientation of the terminals on your device may be different.
The drawing below is an example.
A. Voltage source
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