Siemens SITRANS L Operating Instructions Manual page 144

Parameter reference
Limit Hysteresis (2.6.6.5.)
Hysteresis is used to adjust the sensitivity of the trigger for alarm messages. It is used to
compensate when a process variable fluctuates around the same value as a limit. A high level
alarm occurs when a value exceeds an upper limit. The alarm's status remains true until the
value drops below the limit minus the alarm hysteresis. The directions are reversed for low
limit detection.
Values
Enter a value for the hysteresis here, to be used for all warnings and alarms. The units are the
same as the Output scale, i.e. AIFB1 units.
Display (2.6.7.)
Filter Time Constant (2.6.7.1.)
The time constant for the damping filter. The damping filter smooths out the response to a
sudden change in level. This is an exponential filter and the engineering unit is always in
seconds. See Damping (Page 240) for more detail.
Values
a) To meet accuracy specification, Filter Time Constant (PV_FTIME) must be changed from
default of 0.0 s to a minimum of 10.0 seconds [see Performance (Page 178)].
AIFB 2 (2.7.)
See AIFB1 (2.6.): the parameters for AIFB 2 are identical to AIFB 1.
Measured Values (2.8.)
(for diagnostic purposes)
Read only. Allows you to view measured values for diagnostic purposes.
Main Output (PV - Primary Value) (2.8.1.)
The value for level, or volume (if volume conversion is selected).
In AMS Device Manager, see Process Variables Level Transducer Block-LTB (Page 105).
Output, no linearization (SV1 - Secondary Value 1) (2.8.2.)
The value for level.
144
Range: 0 to 50
Default: 0.50
Range: 0 to 600 s
Default: 0
a)
SITRANS LR250 with FOUNDATION FIELDBUS
Operating Instructions, 09/2021, A5E32221411-AH