Endress+Hauser Liquiline CM44P - Page 104

Operation Liquiline CM44P
104 Endress+Hauser
Menu/Setup/Additional functions/Limit switches/Limit switch 1 ... 8
Function Options Info
Hysteresis Settings depend on the
measured value
Operating mode ≠ Change rate
1
3
t
MV
t
1
t
2
2
A0028525
 88 Hysteresis taking the example of limit value
overshoot
1 Limit value
2 Alarm range
3 Hysteresis range
t
1,2
An event is generated
The hysteresis is needed to ensure a stable
switching behavior.
The device software adds or subtracts the value
set here to/from the limit value (Limit value,
Range lower value or Range upper value). This
results in double the Hysteresis value for the
hysteresis range around the limit value. An
event is then only generated if the measured
value (MV) completely passes through the
hysteresis range.
Start delay
Operating mode ≠ Change
rate
0 to 9999 s
Factory setting
0 s
Synonyms: pick-up and drop-out delay
Switch off delay
Operating mode ≠ Change
rate
Delta value Settings depend on the
measured value
Operating mode = Change rate
The slope of the measured value (MV) is
monitored in this mode.
If, in the specified time frame (Delta time), the
measured value increases or decreases by more
than the specified value (Delta value), an event
is generated. No further event is generated if the
value continues to experience such a steep
increase or decrease. If the slope is back below
the limit value, the alarm status is reset after a
preset time (Auto Confirm).
Events are triggered by the following conditions
in the example given:
t
2
- t
1
< Delta time and ∆MV1 > Delta value
t
4
- t
3
>Auto Confirm and ∆MV2 < Delta value
t
6
- t
5
< Delta time and ∆MV3 > Delta value
Delta time 00:00:01 ... 23:59:00
Factory setting
01:00:00
Auto Confirm 00:01 to 23:59
Factory setting
00:01
t
MV
t
1
t
2
t
3
t
4
t
5
t
6
MV
1
MV
2
MV
3
A0028526
 89 Rate of change
10.6.2 Time switch
A time switch provides a time-controlled, binary process value. This can be used as a
source by the "Formula" mathematical function.