Emerson AMS Trex Device Communicator User Manual page 146

Loop Diagnostics application
September 2021
4.10.2
4.10.3
4.11
146
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Change the scale for the up and down arrow keys
The Loop Diagnostics screen has up and down arrow keys that let you manually adjust the
current in small increments to slowly move a valve. The default increment is 0.1 mA, but
you can adjust the scaling.
Procedure
1. On the Loop Diagnostics screen, tap Trex Unit Current → More Options → Arrow
Scaling for mA.
More Options does not appear unless the Trex Unit Power or Trex Unit Current is
enabled.
2. Enter a value between 0.04 to 10.00 mA.
3. Tap OK.
4. Tap Back to save the changes and return to the Loop Diagnostics screen.
Set the duration to change the current
You can control how long it takes the Trex unit to change from sourcing one current value
to another. Select a higher value to gradually change the current and avoid abrupt
changes to a valve's position that may damage equipment. Select a value of zero to quickly
move a valve.
This option applies to the quick current buttons, the up and down arrow keys, and the
pencil icon that enable you to enter a new current value. It also applies when you tap Trex
Unit Power to stop powering the positioner.
Note
This option does not apply to the initial current value that is applied when you first power
the device. For example, if you power a device, the Loop Diagnostics application will
immediately source 4 mA, 20 mA, or the mA value you entered. The delay applies to any
change to the current value after initial start up.
Procedure
1. On the Loop Diagnostics screen, tap Trex Unit Current → More Options →
Duration of Current Change.
More Options does not appear unless the Trex Unit Power or Trex Unit Current is
enabled.
2. Tap the desired number of seconds.
3. Tap OK.
4. Tap Back to save the changes and return to the Loop Diagnostics screen.
Loop checks
The Loop Diagnostics application enables loop checks by measuring voltage and current,
and controlling the current to simulate a transmitter.
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