Simulate a transmitter on an unpowered loop for a loop check

The Trex unit can provide power and control current to simulate a device for a loop check. In this setup, the control system is not providing power to the device. This task is used if the loop will have a 4-wire transmitter.

The Trex unit supplies loop power from the HART + pwr terminals, and Loop Diagnostics lets you control the current on the loop.

  1. Connect the lead set to the HART + pwr terminals on the Trex unit and to the unpowered loop.

    Connection for providing power and simulating a transmitter

    1. Analog input.
  2. On the Loop Diagnostics screen, tap Trex Unit Power.
  3. Tap Simulate Transmitter with 4 mA.
  4. Change the current value by pressing the quick buttons or the up and down arrow keys.
  5. Verify the digital control system is reading the same current value.