Emerson AMS Trex Device Communicator User Manual page 17

User Guide
2.5.2
User Guide
1.800.561.8187
WARNING
• Do not use the HART + pwr and mA terminals in series when the Trex unit powers a
device.
• Do not connect the mA terminals (ammeter) in parallel with a powered 4-20 mA
current loop. Ammeters have low resistance. This can disrupt the loop and cause
devices to report incorrect values or positioners to move unexpectedly.
• Do not connect the mA terminals on the Trex unit to a power supply that is not current
limited to 250 mA. This can blow a fuse inside the Trex unit. The repair/replacement
will need to be completed at an authorized service center.
For best results when using the mA terminals, do the following:
• Avoid using the ammeter in cold or very hot temperatures. Extreme temperatures can
affect the accuracy of the measurements.
• Connect the mA terminals on the Trex unit to the "low-side" of the device. See the
example below.
Figure 2-6: "Low-side" ammeter connection
A. Analog output
Install a communication module
CAUTION
• Ensure sufficient grounding. Ensure the personnel, working surfaces, and packaging
are sufficiently grounded when handling electrostatically sensitive parts.
• Avoid touching the pins on the connectors or components. Discharged energy can
affect the modules.
• Handle the module with care. It is possible to bend the pins on the module's connector.
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