Ams trex™ Device Communicator

not
prompted to select a power
option to set the position of the valve.
4.9
Stroke a valve
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.
 WARNING
Connecting power to the positioner may cause changes to the tuning set that cause the
valve/actuator assembly to stroke. To avoid personal injury and property damage caused
by moving parts, keep hands, tools, and other objects away from the valve/actuator
assembly.
 WARNING
When power is provided to a positioner that is in service, the valve may move causing
process fluid or pressure to be released. To avoid personal injury and property damage
caused by the release of process fluid or pressure, isolate the valve from the process and
equalize pressure on both sides of the valve or bleed off the process fluid.
Procedure
1. Connect the lead set to the 
HART + pwr
terminals on the Trex unit and to the
positioner.
2. On the Loop Diagnostics screen, tap 
Trex Unit Power
.
3. Select one of the following options.
Option
Description
Power Positioner with 4 mA(0%)
Power a positioner with 4 mA.
Power Positioner with 20 mA (100%)
Power a positioner with 20 mA.
Power Positioner with other mA value
Power a positioner with a specified mA
value.
4. Tap 
OK
.
5. To change the current being supplied by the Trex unit, do one of the following:
•
Tap a quick current button.
•
Tap the up or down arrow keys to slowly increase or decrease the current. The
default increment is 0.1 mA.
User Guide 
Loop Diagnostics application
September 2021
User Guide 
143

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•
Tap the pencil icon to set a mA value.
6. Wait for the valve to move.
7. Repeat steps 5 and 6 until the valve moves through all the required positions.
8. 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