Emerson AMS Trex Device Communicator User Manual page 143

User Guide
4.9
User Guide
1.800.561.8187
• 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.
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
Power Positioner with 4 mA(0%)
Power Positioner with 20 mA (100%)
Power Positioner with other 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.
www.
Loop Diagnostics application
Description
Power a positioner with 4 mA.
Power a positioner with 20 mA.
Power a positioner with a specified mA
value.
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September 2021
143