Emerson AMS Trex Device Communicator User Manual page 176

Fieldbus Diagnostics application
September 2021
176
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Low-Frequency noise
In-band frequency noise
Higher than expected
High-frequency noise
Higher than expected
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Possible cause
The device or shield is not
properly grounded.
The power supply is not
supplying a good, stable
voltage.
Possible cause
The device or shield is not
properly grounded.
A cable may be damaged.
Possible cause
There may be loose wire
connections.
Water or moisture may be in
the device's terminal housing.
A cable may be damaged.
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User Guide
Action
Ensure the device is properly
grounded.
Ensure the shield is properly
isolated from the terminal
housing. The shield should be
grounded at only one location
on the entire fieldbus segment
and it should be a high-quality
ground.
Repeat these checks for all
devices on the fieldbus segment.
Ensure the power supply is
properly installed. Isolate the
power supply and check for
noise.
Action
Ensure the device is properly
grounded.
Ensure the shield is properly
isolated from the terminal
housing. The shield should be
grounded at only one location on
the entire fieldbus segment and
it should be a high-quality
ground.
Visually inspect the cables and
test the resistance between the
two wires and each wire against
the ground.
Action
Check for loose connections.
Vibration from nearby motors
or wind gusts may cause loose
connections to be displayed as
high-frequency noise.
Check the device's terminal
housing.
Use the signal or DC voltage
measurement to find the cable
portion that may be damaged.
Visually inspect the cables, and
test the resistance between the
two wires and each wire to the
ground.
User Guide
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