Emerson AMS Trex User Manual page 133

Figure 4-1:
A.
B.
C.
User Guide
Loop Diagnostics screen at start up
Measurement section: Displays the measured voltage and current. The measurements begin
when the Loop Diagnostics screen is displayed, and the measurements update about once per
second. See Section 4.4 for more information about the terminals used for each measurement.
Power/Help section: Lets you enable/disable the Trex unit to power a transmitter or positioner.
The connection diagram on the right shows the terminals on the Trex unit where measurements
are being read.
By default, the HART and mA terminals are circled in green on the connection diagram. The
diagram shows you one setup for reading voltage on the HART terminals and current on the mA
terminals when Trex Unit Power is off. (This setup lets you take the measurements without
interrupting the 4-20 mA current loop by connecting the Trex HART terminals to a transmitter's
communication terminals and connecting the Trex mA terminals to a transmitter's test terminals.)
The connection diagram is updated based on the options you select (Trex Unit Power and Trex Unit
Current).
Current control/output section: Lets you use multiple options for controlling current including
quick buttons, keypad, and up/down keys for immediately adjusting current or for gradually
changing current over 1 to 5 seconds. These options are displayed when either the Trex Unit Power
or Trex Unit Current is ON.
Loop Diagnostics application
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