User's Manual

Appendix A: Technical reference
A.2 Echo processing
SITRANS LR250 (PROFIBUS PA)
Operating Instructions, 01/2014, A5E32221386-AB
211
A.2.10.2
Fail-safe Behavior
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 mode may be triggered by a loss of echo, a bad configuration, or certain device faults.
You can select one of three possible values to be reported when a Fail-safe mode is activated.
Mode
Mode (2.6.9.1.)
determines the material level to be reported when
LOE Timer (2.3.6.)
expires.
Mode (2.6.9.1.)
SUB VALUE
Use substitute value. Value (2.6.9.2.) used as output value.
LAST VALUE
*
Last value (Store last valid output value).
USE BAD VALUE
Use bad value (Calculated output value is incorrect).
Value
Value (2.6.9.2.)
defines the material level to be reported if the option
Use substitute value
is
selected in
Mode (2.6.9.1.)
.
The two Analog Input Function blocks are set separately.
To set a user-defined value
● Navigate to the Level Meter > Setup > desired Analog Input (1 or 2).
● Set
Mode (2.6.9.1.)
to
Use substitute value
.
● Go to
Value (2.6.9.2.)
and enter the desired value.