Simulate a transmitter on an externally-powered loop for a loop check

The Loop Diagnostics application can control current to simulate a 2-wire transmitter on an externally-powered loop. In this setup, the digital control system is powering the current loop and the Trex unit is controlling the current that is input into the digital control system.

  1. Connect the lead set to the HART terminals on the Trex unit and to the powered 4-20 mA current loop.

    Connection for controlling current

    1. Analog input.
  2. On the Loop Diagnostics screen, tap Trex Unit Current.
  3. Tap one of the quick buttons to increase the current being supplied, use the up and down arrow keys, or tap the pencil icon to enter a new value.
  4. Verify the digital control system is reading the same current value.