MEASUREMENT DIFFICULTIES
If a measurement difficulty occurs for greater than the Failsafe Timer (P070) setting, "LOE" is flashed
alternately with the Reading display. Under certain conditions, a measurement difficulty may cause the XPL+
to "lock on" to a false echo and report a fixed or wrong Reading.
FLASHING "LOE" DISPLAY
If "LOE" is displayed, ensure the:
1. Material (object) surface monitored is within the maximum range of the transducer.
2. Transducer (P004) value matches the transducer used.
3. Transducer is located and aimed properly.
( See the Transducer manual for the maximum range, mounting and rough aiming instructions.)
For optimum performance, adjust the transducer aiming while monitoring the Echo Confidence (P805) for
various material levels over the measurement range. When complete, set the transducer aiming at the best
angle for all levels.
To display Echo Confidence in the RUN mode...
and hold for 4 seconds (Failsafe Time Left changes to the Short:Long
Confidence display).
To display Echo Confidence in the program mode, access the Echo Confidence (P805) parameter. To
update the value displayed after each aiming adjustment...
(5 times or more to verify stability)
If the condition persists (despite optimum aiming), optimize transducer performance. Adjust Short Shot
Frequency, (P842) and Long Shot Frequency, (P843) for maximum Echo Confidence (P805).
Increase the Failsafe Timer (P070) value, if failsafe operation will not be compromised by the larger value.
If "LOE" is displayed only when a sloped bottom vessel is near Empty, the echo is probably being reflected
away from the transducer. Install an empty "target plate" in the bottom of the vessel. When exposed (not
covered by material), the target plate provides the reflective surface representative of an empty vessel.
Install a longer range transducer, enter the new Empty (P006) distance, and ( if necessary ) optimize aiming
and frequency again.
If a longer range transducer is not available, connect an oscilloscope to the XPL+
(see ENHANCEMENT PARAMETERS Scope Displays, P810).
If a discernible echo is observed ( representative of the material/object surface ), reduce the Confidence
Threshold (P804) while taking new measurements (in the RUN or program mode).
Sometimes, material simply cannot be detected during vessel filling. In these cases, set up failsafe operation
such that the XPL+ "anticipates" the rate of material level increase and adjusts the reported Reading
accordingly. This operation is reliable, as long as when the dust (or foam) settles a valid echo can be
received. See TECHNICAL REFERENCE Application Examples \ Example 1 - Level Measurement.
TECHNICAL REFERENCE
ENHANCEMENT PARAMETERS
PL-532 100
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