SM500F
Field mountable paperless recorder
7 Configuration
IM/SM500F Rev. Z
103
Fig. 7.15 Delayed High/Low Process Alarms
Hyster
esis
Alarm On
Alarm Disabled
Alarm Enabled
Trip Point
Alarm Of
f
Delay T
ime
Pr
ocess
Variable
Pr
ocess variable goes
above
trip
point
but
alarm
is not activated because enable
signal
is
low
(Alarm
Disable).
Pr
ocess variable goes
below trip (hyster
esis)
point ther
efor
e alarm is
de-activated.
Alarm Enable signal is switched On. Alarm delay timer is started.
Pr
ocess variable goes
above
trip
point
but
alarm
is not activated because alarm delay time has not expir
ed.
Alarm delay timer expir
es,
alarm
is
now
enabled.
Alarm
is
activated
because
pr
ocess
variable is above trip point.
Pr
ocess
variable
goes
above
trip point, alarm is activated (alarm is enabled and delay time has expir
ed).
Alarm Enable signal is switched Of
f. Alarm is
disabled immediately
.
Alarm de-activates.