33
7-2. Hysteresis
Using this function, You can buffer the set points at which the HH, HI, LO, and LL decision outputs switch off.
If fluctuations in the reading occur near each comparative point, the corresponding decision output switches on and off, which is a
phenomenon called “chattering.” You can prevent the output from chattering by setting a hysteresis value.
Hysteresis for the HH and HI values is enabled when the reading decreases, and hysteresis for the LL and LO values is enabled when
the reading increases, as shown below.
HI/HH
Hysteresis
Hysteresis
LO/LL
OFF
ON
HH/HI
Time
Reading
OFF
ON
LL/LO
Time
Reading
HI/HH
Decision output
Disable hysteresis
HI/HH
OFF
ON
HH/HI
OFF
ON
Hysteresis
Enable hysteresis
Decision output
Conditions for generating decision outputs (with “standard output” selected for Comparative Output Pattern)
Decision
output
State
Condition
HH
OFF
w
ON
HH value < reading
ON
w
OFF Reading (HH value – hysteresis value)
HI
OFF
w
ON
HI value < reading
ON
w
OFF Reading (HI value – hysteresis value)
LO
OFF
w
ON
Reading < LO value
ON
w
OFF (LO value + hysteresis value) reading
LL
OFF
w
ON
Reading < LL value
ON
w
OFF (LL value + hysteresis value) reading
CAUTION
Set a hysteresis value to meet the following conditions.
HI value (HH value - hysteresis value)
LO value (HI value - hysteresis value)
LL value (LO value - hysteresis value)
NOTE
<
The same amount of hysteresis is set for HI, LO, HH, and LL values.
<
If the setting is 0, hysteresis is disabled.
7. Setting Functions