Loss Of Echo (Loe); Fail-Safe Mode; Fail-Safe Timer; Fail-Safe Value - Siemens Sitrans LR250 Instruction Manual

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.
If the LOE condition persists beyond the time limit set in
displays the Service Required icon, and the text region displays the fault code S: 0 and the
text LOE.
If two faults are present at the same time, the fault code, error text, and error icon for
each fault are displayed alternately. For example, Loss of Echo and Fail-safe High.
S: 0 LOE

Fail-safe Mode

The purpose of the Fail-safe setting is to put the process into a safe mode of operation in
the event of a fault or failure. The value to be reported in the event of a fault is selected so
that a loss of power or loss of signal triggers the same response as an unsafe level.

Fail-safe Timer

Fail-safe Timer determines the time to elapse after the last valid reading before a Fail-
safe state is activated. Fail-safe Material Level determines the level to be reported when
the Fail-safe timer expires. Upon receiving a reliable echo, the loss of echo condition is
aborted, the Service Required icon and error message are cleared, and the reading and
mA output return to the current level.

Fail-safe value

2.4.1. Fail-safe Timer
When the
2.4.2. Fail-safe Material Level
HI
LO
HOLD
VALUE
Page 108 SITRANS LR250 (HART) – INSTRUCTION MANUAL
S: 52 FAIL-SAFE
expires, the material level to be reported is determined by
.
Fail-safe Material Level
Use Maximum mA Limit as material level
Use Minimum mA Limit as material level
Level remains at last reading
User-selected value
2.4.1. Fail-safe Timer
the LCD
7ML19985JE01