If you try to apply power from the Trex unit when the device is externally-powered, the Loop Diagnostics application prevents the Trex unit from supplying power. This protects the Trex unit from damage.
Connect the lead set to the
HART + pwr terminals on the Trex unit and to
Connection for powering a positioner
- On the Loop Diagnostics screen, tap Trex Unit Power.
Select one of the following:
Option Description Power Positioner with 4 mA (0%) Power a positioner using 4 mA. Power Positioner with 20 mA (100%) Power a positioner using 20 mA. Power Positioner with other mA value Power a positioner using a specified mA value.
Loop Diagnostics is now powering the positioner and measuring voltage and current. The Trex Unit Current option is also enabled.
- To change the current value, tap one of the quick current buttons (4 mA, 8 mA, 12 mA, 16 mA, 20 mA), or use the up and down arrow keys to manually increase the current value. The default increment is 0.1 mA.
To stop powering the device, do one of the following:
- Tap Trex Unit Power to set the option to OFF. You are prompted to select a power option to set the position of the valve.
- Tap Exit. You are prompted to select a power option to set the position of the valve.
- Remove the lead set from the Trex unit. You are not prompted to select a power option to set the position of the valve.