Honeywell 900 - Alarm Setpoints

Loops
Loop Setup
156 900 Control Station User Guide Revision 9
May 2014
Alarm setpoints
This display shows the loop’s setpoints and alarm types. A loop can have two alarms; and each loop alarm
can have two setpoints and types.
Item Description
Alarm 1 Setpoint 1 The value at which the alarm will activate.
Alarm 1 Type 1
No Alarm
PV High - Alarm when PV is greater than the alarm setpoint
PV Low - Alarm when PV is less than the alarm setpoint
Dev High - Alarm when PV - SP is greater than the alarm setpoint.
Dev Low - Alarm when SP - PV is greater than the alarm setpoint.
SP High - Alarm when SP is greater than the alarm setpoint
SP Low - Alarm when SP is less than the alarm setpoint
Out High - Alarm when output is greater than the alarm setpoint
Out Low - Alarm when output is less than the alarm setpoint
Alarm 1 Setpoint 2 same as Alarm 1 Setpoint 1
Alarm 1 Type 2 same as Alarm 1 Type 1
Alarm 2 Setpoint 1 same as Alarm 1 Setpoint 1
Alarm 2 Type 1 same as Alarm 1 Type 1
Alarm 2 Setpoint 2 same as Alarm 1 Setpoint 1
Alarm 2 Type 2 same as Alarm 1 Type 1
Alarm Hysteresis Affects the point at which an alarm clears. For Out High and Out Low
alarms, hysteresis is % of the loop’s output span. For all other alarm
types, it is % of PV span.
PV High - Alarm clears when PV is less than the alarm setpoint by the
amount of hysteresis.
PV Low - Alarm clears when PV is greater than the alarm setpoint by the
amount of hysteresis.
SP High - Alarm clears when SP is less than the alarm setpoint by the
amount of hysteresis.
SP Low - Alarm clears when SP is greater than the alarm setpoint by the
amount of hysteresis.
Out High - Alarm clears when output is less than the alarm setpoint by
the amount of hysteresis.
Out Low - Alarm clears when output is greater than the alarm setpoint by
the amount of hysteresis.
Dev High - Alarm clears when PV - SP is less than the alarm setpoint by
the amount of hysteresis.
Dev Low - Alarm clears when SP - PV is less than the alarm setpoint by
the amount of hysteresis.
TIP
These Loop Alarm parameters are used to set the conditions under which loop alarms occur;
they do not generate the alarm. To generate the alarm, AL1 and AL2 pins of loops should be
connected to the Signal Tags in HC Designer. These signal tags can be configured to generate
alarms in Station Designer.