Siemens LR 460 Echo confidence, Fail-safe Mode, Near Range Blanking, Loss of Echo LOE, LOE Timer

A: Technical Reference

Near Range (Blanking)

Note: Auto False-Echo Suppression is generally recommended in preference to using 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 Unreliable 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.

Page A-74 SITRANS LR 460 – INSTRUCTION MANUAL 7ML19985JM01