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4.2.1
View the connection diagram as a full-screen image
The Loop Diagnostics screen displays an image of the terminals on the Trex unit to help
you make the correct connection and to see where the measurements are read. The image
changes to display the correct connection for a desired task, based on the measurements
or options you selected. You can view a full-screen version of this image.
Procedure
1.
2.
4.3
Powering transmitters or positioners from
Loop Diagnostics
The Trex Unit Power option in the Loop Diagnostics application enables the Trex unit to
power one transmitter or positioner in a bench setup. This lets you isolate a problematic
device from its HART loop and verify its operation, or perform wiring continuity checks on
cables where no power exists.
Use the HART + pwr terminals on the Trex unit to connect to the transmitter or positioner.
When you tap the Trex Unit Power option, you can select the type of device (transmitter or
positioner) to power.
The Trex unit notifies you if it measures voltage at the HART + pwr terminals when you try
to turn on Trex Unit Power. If the measured voltage is less than 8 volts, the Loop Diagnostics
application assumes that the voltage may be from the device, and you can select to ignore
the low voltage and provide power from the Trex unit. If the voltage is greater than or
equal to 8 volts, the Loop Diagnostics application will not let you enable Trex Unit Power to
power a device.
The Trex Unit Power immediately turns off if the Loop Diagnostics application detects one of
the following:
•
•
•
User Guide
Tap the image of the terminals on the Loop Diagnostics screen.
A larger image is displayed.
Tap OK to close the full-screen view, and return to the Loop Diagnostics screen.
A short circuit.
The lead set is no longer connected to the device.
A very high device-load that exceeds the capacity of the Trex Unit Power option.
Loop Diagnostics application
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Table of Contents
Troubleshooting
