Near Range (Blanking); Echo Confidence; Loss Of Echo (Loe); Loe Timer - Siemens SITRANS LR460 HART Operating Instructions Manual

Near Range (Blanking)

Auto False-Echo Suppression is generally recommended in preference to using
Note:
Near Range.
Near Range allows you to set a distance in front of the antenna, within which any echoes
will be ignored.

Echo confidence

Echo confidence is an internally generated numeric rating given to an echo based on its
relative strength, area, and height.

Loss of Echo (LOE)

A loss of echo (LOE) occurs when the calculated measurement is judged to be unreliable
because the echo confidence value has dropped below the echo confidence threshold.
The LOE timer starts running, and if the LOE condition persists beyond ten minutes (the
time limit set by the LOE timer) the Unreliable Echo indicator replaces the Reliable Echo
indicator.
Reliable Echo indicator
While LOE is pending the x flashes, alternating with the two horizontal bars. When LOE
becomes active, the x becomes solid and the auxiliary display shows fault code S: 0.
Upon receiving a reliable echo, the loss of echo condition is aborted, the Reliable Echo
indicator reappears, and the reading returns to the current level.

LOE Timer

The LOE timer determines the time (in minutes) to elapse after the last valid reading
before Fail-safe mode is activated. When the LOE timer expires, the material level to be
reported is determined by Fail-safe Mode.
Fail-safe Mode
Fail-safe mode defines the reaction of the device if a Fail-safe condition is detected, so
that the process will be put into a safe state in the event of a fault or failure. The
particular application determines whether a high or low level is safe.
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Unreliable Echo indicator
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