17
5 SETTING OF FUNCTIONS
17
SETTING OF FUNCTIONS
Chapter
5
5-2. Hysteresis
The hysteresis value may be determined so as to allow a margin for timing the turning off of the HI/
LO limit comparison. Normally, it is turned on when the indicated value exceeds the HI limit and is
turned off when the indicated value falls below it. However, by setting the hysteresis, it is turned off
when the indicated value falls below the HI limit further lowered by the hysteresis value. This
function is effective to prevent chattering in such a case where signals fluctuate (vibrate) subtly.
< Comparison conditions >
- HH
ON condition: Indicated value > HH limit value
OFF condition: Indicated value ≦ (HH limit value - hysteresis value)
- HI
ON condition: Indicated value > HI limit value
OFF condition: Indicated value ≦ (HI limit value - hysteresis value)
- LO
ON condition: Indicated value < LO limit value
OFF condition: Indicated value ≧ (LO limit value + hysteresis value)
- LL
ON condition: Indicated value < LL limit value
OFF condition: Indicated value ≧ (LL limit value + hysteresis value)
< The example of hysteresis operation >
Hysteresis setting is the same for HH/HI/LO/LL limit.
Point
HI limit
LO limit
＋
0
Hysteresis range
Time
－
Indicated value
OFF
ON
With hysteresis
Without hysteresis
By setting hysteresis, cha
ttering can be prevented
in such a case as subtle
fluctuations of signals.
HI limit
HI
LO
OFF
ON
OFF
ON
OFF
ON
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