Alarm Reset (rSt1, rSt2)
Each alarm reset action may be independently configured.
LAtC - Latched
Auto - Automatic
Latched alarms require operator action to reset the alarm condition. The
front panel buttons can be used to reset an alarm when the controller is in the
Hidden Function Mode (See page 20). An alarm condition may also be reset
via the user input.
Automatic reset alarms are reset by the controller when the alarm condition
clears. Figure 17, Alarm Reset Sequence, depicts the reset actions.
Alarm Standby Delay (Stb1, Stb2)
The alarm(s) may be independently configured to exhibit a power-on,
standby delay which suppresses the alarm output from turning “ON” until the
temperature first stabilizes outside the alarm region. After this condition is
satisfied, the alarm standby delay is canceled and the alarm triggers normally,
until the next controller power-on. This feature also works for deviation and
band alarms when the setpoint is changed via keypad. This action suppresses
“nuisance” alarms. Figure 18, Alarm Standby Delay Sequence, depicts a
typical operation sequence.
Alarm Value (AL-1, AL-2)
The alarm values are either absolute (absolute alarms) or relative to the
setpoint value (deviation and band alarms). An absolute alarm value is the value
that is entered. A relative alarm value is offset from the temperature setpoint
value by the amount entered and tracks the setpoint value as it is changed.
AL-1 and AL-2 - -999 to 9999
If the alarm action is set as a Band Alarm, then only a positive value can be
entered.
Alarm Hysteresis (AHYS)
The alarm value(s) have a programmable hysteresis band to prevent alarm
output chatter near the alarm trigger point. The hysteresis value should be set to
eliminate this effect. A value of 2 to 5 is usually sufficient for most applications.
A single alarm hysteresis value applies to both alarms. See the Alarm Action
Figures, page 40, for the effect of hysteresis on the various alarm types.
AHYS - 1 to 250
-42-
Figure 17, Alarm Reset Sequence
Figure 18, Alarm Standby Delay Sequence
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