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Reference Manual
00809-0200-4840, Rev BA
Section 5: Service and Troubleshooting
December 2014
Section 5: Service and Troubleshooting
5.2
Servicing
The only maintenance required is to occasionally check the transmitter face to ensure it remains
clean and check that the wiring is in good condition. There are no spare parts for the
transmitter. If a problem persists, contact Rosemount Inc. for advice.
5.3
Power failure
All parameters are held in EPROM memory. In the event of a power failure, or disconnection
from the power supply, the transmitter will remember all of it's last parameter values and will
resume correct operation once power is restored.
5.4
False echoes under certain ambient operating
conditions
In applications where elevated ambient temperatures of around 50 to 60 °C are experienced,
together with poor liquid surface conditions (excessive surface agitation, foam, etc.) at a high
level and within 0.5 m of the transducer face, the transmitter may see a false echo and report a
false high level measurement.
If this situation happens, with reference to
and this section, there are two
field-configurable resolutions:
Upper Blanking Distance (P023)
The factory default value of this parameter is 0.3 m, measured down from the
transducer face.
If it is possible to operate with an increased value between 0.3 and 0.5 m, then setting
P023 to a value of 0.5 m eliminates the false echo. Trying several different values is
recommended as a smaller value of P023, if the application requires, may be possible.
Threshold 1 Size (P048)
The factory default value of this parameter is 4%.
If the false echo is reported at the end of the Upper Blanking Distance (0.3 m or as
adjusted in P023 above), then it is recommended to set the value of parameter
Threshold 1 Size (P048) to a value sufficient to ignore this false echo. This should be
implemented by reading the size of the false echo (see D911 on
), and setting
the P048 to a value 4% greater than the reported value in D911.
Note that this particular approach has an impact on the liquid level reading accuracy
when the liquid level is within approximately 0.5 m of the transducer face. The accuracy
may be reduced from ±2.5 to +2.5/-5.5 mm or, in extreme conditions, +2.5/-8.5 mm.
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