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3.5
Alarm
The controller has up to four alarm outputs depending on the controller model. There are 11 types of alarm
functions and one dwell timer that can be selected. There are 4 kinds of alarm modes (A1MD, A2MD, A3MD,
and A4MD) available for each alarm function (A1FN, A2FN, A3FN, and A4FN). In addition to the alarm
output, output 2 can also be configured as an alarm. But output 2 has only 8 different alarm functions or dwell
timer available.
3.5.1
Alarm Types
There are 11 different types of alarms shown below that the user can assign to different alarm outputs.
1.
dtMR:
Dwell timer
2.
dE.HI:
Deviation high alarm
3.
dE.Lo:
Deviation low alarm
4.
dB.Hi:
Deviation band out of band alarm
5.
dB.Lo:
Deviation band in band alarm
6.
PV.HI:
Process value high alarm
7.
PV.Lo:
Process value low alarm
8.
H.bK
: Heater break alarm
9.
H.St:
Heater short alarm
10.
E1.C
.o:Event Input 1 Control Alarm Output
11.
E2.C
.o:Event Input 2 Control Alarm Output
The
Dwell timer
can be used separately or accompanied with a Ramp. Alarm outputs can
be configured as dwell timers by selecting “dtMR” for A1FN. If A1FN is set to “dtMR”, Alarm 1 will act as a
dwell timer. Similarly, Alarm 2, Alarm3, or Alarm4 will act as dwell timers if A2FN, A3FN, or A4FN is set to
“dtMR”. When the dwell timer is configured, the parameter “dtMR” is used for dwell time adjustment.
A deviation alarm energizes when the process value deviates too far from the set point.
-
When the process value is higher than SV+A1DV, a
deviation high alarm (dE.HI)
occurs. The alarm is off
when the process value is lower than SV+A1DV-A1HY.
-
When the process value is lower than SV+A1DV, a
deviation low alarm (dE.Lo)
occurs. The alarm is off
when the process value is higher than SV+A1DV+A1HY.
The trigger level of a deviation alarm moves with the set point.
A deviation band alarm presets two trigger levels centered on the set point.
The two trigger levels are SV+A1DV and SV–A1DV. When the process value is higher than (SV+A1DV) or
lower than (SV – A1DV), a
deviation band high alarm (dB.HI)
occurs. When the process value is within the
trigger levels, a
deviation band low alarm (dB.Lo)
occurs.
In the above descriptions, SV denotes the current set point value for control.
A process alarm can set two absolute trigger levels. When the process value is higher than
A1SP, a
process high alarm (PV.HI)
occurs. The alarm is off when the process value is lower than A1SP-
A1HY. When the process value is lower than A1SP, a
process low alarm (PV.Lo)
occurs. The alarm is off
when the process is higher than A1SP+A1HY. A process alarm is independent of the set point.
