User manual

6 Detailed descriptions of I/O modules | Digital counter module UR20-1CNT-100-1DO
345Manual u-remote1432790000/08/12.2015
Hysteresis
It is possible to reduce frequent switching of the output and/
or triggering of a process alarm, e.g. if the value of a sensor
signal fluctuates around the comparison value, by setting the
hysteresis. Thereby you dene a range above and below a
reference value (zero crossing, overow/underow or compa-
rison value), within which the output will not be reset.
A limit value between 0 and 255 can be parameterised for
the hysteresis. With hysteresis = 3 for example, all values
differing less than 3 from the reference value are smoothed.
Hysteresis is deactivated with the values 0 and 1.
The hysteresis is activated upon reaching the comparison
condition. The comparison result remains unchanged during
active hysterersis until the counting value reaches the prede-
termined hysteresis limit. After leaving the hysteresis range,
hysteresis is reactivated only upon reaching the comparison
condition again.
After changing the hysteresis value, an active hysteresis re-
mains active. The new hysteresis value is actived during the
next hysteresis event.
The behaviour of the output for hysteresis=0 (hysteresis
deactivated) and hysteresis= 3 is shown in the following
diagrams (legends describe the behaviour for hysteresis=3):
Counting value
Output:
Hysteresis = 0
Hysteresis = 3
1 2 3 4 75 6
Comparison
value
9 8 7 6
5
4 3 2 1 0
Operating principle of the hysteresis when counter value ≥ comparison value, pulse duration 0
1 Comparison condition met ➝ output is set and hysteresis activated
2 Comparison condition not met, leaving the hysteresis range ➝ output is
reset
3 Comparison condition met ➝ output is set and hysteresis activated
4 Leaving the hysteresis range, the output remains set because the compari-
son condition is still met
5 Comparison condition no longer met but hysteresis still active ➝ output
remains set
6 Comparison condition met, hysteresis still active ➝ output remains set
7 Leaving the hysteresis range and comparison condition met ➝ output
remains set
Counting value
Output:
Hysteresis = 0
Hysteresis = 3
1 2 3 4 75 6
Comparison
value
9 8 7 6
5
4 3 2 1 0
Operating principle of the hysteresis when counter value = comparison value, pulse duration 0
1 Comparison condition met ➝ output is set and hysteresis activated
2 Comparison condition not met, leaving the hysteresis range ➝ output is
reset
3 Comparison condition met ➝ output is set and hysteresis activated
4 Leaving the hysteresis range and comparison condition not met ➝ output
is reset
5 Comparison condition met ➝ output is set and hysteresis activated
6 Comparison condition met and hysteresis active ➝ output remains set
7 Leaving the hysteresis range and comparison condition no longer met ➝
output is reset
Counting value
Output:
Hysteresis = 0
Hysteresis = 3
Pulse duration = 2
1 2 3 4 75 6
Comparison
value
9 8 7 6
5
4 3 2 1 0
Operating principle of the hysterersis when counter value = comparison value, pulse duration 2
1 Comparison condition met ➝ pulse of the parameterised duration is output,
hysteresis activated
2 Leaving the hysteresis range ➝ hysteresis deactivated
3 Comparison condition met ➝ pulse of the parameterised duration is output,
hysteresis activated
4 Leaving the hysteresis range ➝ hysteresis deactivated
5 Comparison condition met ➝ pulse of the parameterised duration is output,
hysteresis activated
6 Comparison condition met and hysteresis active ➝ no pulse
7 Comparison condition not met, leaving the hysteresis range ➝ hysteresis
deactivated