Emerson AMS Trex Device Communicator User Manual page 82

Field Communicator application
September 2021
82
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Connections to externally-powered transmitters
To enable the internal resistors, the Trex unit must be connected to the device/loop in a
specific way.
For externally-powered 2-wire HART devices, the Trex unit must be connected in series. In
the diagram below, the Trex internal resistor is enabled in the HART terminals.
Figure 3-25: Connection for using the Trex internal resistor for an externally-powered
2-wire transmitter
A. Voltage source
For 4-wire transmitters, the Trex unit must be connected in parallel. In the diagram below,
the Trex internal resistor is enabled in the HART terminals.
Figure 3-26: Connection for using the internal resistor for a 4-wire transmitter
A. Voltage source
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