<5. Functions>
128
IM 01E21A02-03EN
When the high and low limit alarms are reset, each has a hysteresis. The hysteresis width should
besetwiththepercentage(%)forthespanofthephysicalquantityPV-mappedinSubsection
5.1.2.Thehysteresisineachcasecanbespeciedwiththefollowingparameter.
Menu path
Display --
F
OUNDATION
Fieldbus
Diagnostic►AI1*►DeviceDiagnostics►Diagnostics/Alerts►Alert►AlertCommon►
(seebelow)
*For AXG, one from Al1 to Al4, and for AXW, one from AI1 to AI3.
Block Name
Relative
Index
Parameter
Description
Display F
OUNDATION Fieldbus
AI1-AI4(AXG)
AI1-AI3(AXW)
24 - Alarm Hysteresis
Speciesthehysteresiswidth
for the alarm occurrence and
resetting.
(1) Hysteresisvalue=Spanormax.rangexHysteresiswidth[%]
(2) Valuethatcausesahighorhigh-highlimitalarmtobereset
 =Sethighlimitorhigh-highlimit-Hysteresisvalue
(3) Valuethatcausesaloworlow-lowlimitalarmtobereset
 =Speciedlowlimitorlow-lowlimitvalue+Hysteresisvalue
Example:
Spanofvolumetricowrate=300m
3
/h,
Highlimitvalue=250m
3
/h,Lowlimitvalue=50m
3
/h,
High-highlimit=300m
3
/h,Low-lowlimit=25m
3
/h,
If Hysteresis width is set to 5 %
In this case, each value is obtained as shown below.
(1) Hysteresisvalue=300[m
3
/h]x5[%]=15[m
3
/h]
(2-1) Valuethatcausesahigh-highlimitalarmtobereset
 =300[m
3
/h]–15[m
3
/h]
 =285[m
3
/h]
(2-2) Valuethatcausesahighlimitalarmtobereset
 =250[m
3
/h]–15[m
3
/h]
 =235[m
3
/h]
(3-1) Valuethatcausesalowlimitalarmtobereset
 =50[m
3
/h]+15[m
3
/h]
 =65[m
3
/h]
(3-2) Valuethatcausesalow-lowlimitalarmtobereset
 =25[m
3
/h]+15[m
3
/h]
 =40[m
3
/h]