Technical data

Drive functions
7.3 Function modules
Function Manual
316 Function Manual, 06/2012, 6SL3097-4AB10-0BP4
7.3.8.25 LVM (double-sided limit monitor with hysteresis)
Brief description
● This BOOL-type function block monitors an input variable by comparing it with selectable
reference variables.
● Application:
– Monitoring setpoints, actual, and measured values
– Suppressing frequent switching (jitter)
● This function block provides a window discriminator function.
Mode of operation
This function block uses a transfer characteristic (see transfer characteristic) with hysteresis
to calculate an internal intermediate value.
The intermediate value is compared with the interval limits and the result is output at outputs
QU, QM, and QL.
The transfer characteristic is configured with the values for the mean value M, the interval
limit L, and the hysteresis HY.
Transfer characteristic
1
0
QL
QM
0
1
QU
0
1
HY
L
M-L
L
HY
M+LM
Figure 7-78 LVM (double-sided limit monitor with hysteresis): Transfer characteristic