Fieldbus functionality
77
RUNNING FIELDBUS
DIAGNOSTICS
The Fieldbus Diagnostics menu lets you run diagnostics to
troubleshoot fieldbus networks and devices. You can check the DC
voltage, the noise level at low frequencies, and the signal level and
communication status. The selected tests are automatically repeated
and the test results are updated in the Diagnostics Results window.
To view the values associated with the status indicators or the possible
causes of the values, run the diagnostic test, highlight the test on the
Diagnostics Results window, and tap HELP.
DC voltage measurement The DC voltage test displays the amount of DC voltage on a segment.
The word Limit appears if the DC voltage measurement is out of the
-37 V to 37 V range. If the DC voltage is out of this range, there may be
a faulty terminator, wiring problem, or power supply problem.
This test displays the measurement value, measurement unit, and one
of the status indicators listed below.
OK - The value is within the acceptable range.
High - The value is greater than 32 V.
Low - The value is less than 9 V.
Error - There is an error in the measurement or within the 475 Field
Communicator.
Noise level measurement The noise level test displays the amount of noise on the segment. The
word Limit appears if the noise level measurement is greater than 1.0
V. If the low frequency noise is too high, the power supply or power
conditioner may be faulty.
This test displays the measurement value, measurement unit, and one
of the status indicators listed below.
OK - The value is within the acceptable range.
High - The value is greater than 75mv from peak to peak.
Error - There is an error in the measurement or within the 475 Field
Communicator.
Signal level measurement The signal level test determines if a 475 Field Communicator can
receive signals from devices on a segment. To measure the fieldbus
signal level, make sure a LAS is on the segment. Up to 16 different
nodes are checked. The word Limit appears if the signal level value is
greater than 1.3 V. The word Low appears if the signal level value is
less than 100 mV.
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