Installation manual

Introduction
900M050U00  Athena Controls, Inc. 1-13
1.7 Alarm Annunciation
1.7.1 Using LEDs
The 16C, 18C, and 25C controllers all have two alarm LEDs on the front panel. Each of
these LEDs is associated with an alarm. Each alarm can be configured to be activated
(light the LED) when a specific condition exists. The AlrAlr (alarm) menu is used to
configure the alarms associated with the LEDs.
• process alarm – Activated when the process variable reaches the alarm value
(alarm setpoint parameter value), independent of the PV’s relationship to the
process setpoint. A high process alarm activates at and above the alarm
setpoint. A low process alarm activates at and below the alarm setpoint. For
example, if you want an alarm to alert the operator when the PV goes up to 200,
then configure the alarm as a high process alarm, and specify the alarm setpoint
as 200.
• deviation alarm – Activated when the process variable deviates from the
process setpoint by the amount specified using the alarm setpoint parameter
value. A high deviation alarm activates when the PV is above the process
setpoint by the amount specified using the alarm value. A low deviation alarm
activates when the PV is below the process setpoint by the amount specified
using the alarm value. For example, if you want an alarm to alert the operator
when the PV is 50 below the setpoint, then configure the alarm as a low deviation
alarm, and specify the alarm value (using the alarm setpoint parameter) as 50.
• inverse band alarm – Activated when the process value is within a specified
band centered around the setpoint. For example, if you want the alarm to alert
the operator when the PV is 10 units (or less) above or below the process
setpoint, then configure the alarm as an inverse band alarm, and specify 10 for
the alarm setpoint parameter value.
• normal band alarm – Activated when the process value is outside a specified
band centered around the setpoint. For example, if you want the alarm to alert
the operator when the PV is 10 units (or more) above or below the process
setpoint, then configure the alarm as a normal band alarm, and specify 10 for the
alarm setpoint parameter value.
The type of alarm (process high, process low, deviation high, deviation low, inverse band,
or normal band) is referred to as the alarm operation. The alarm menu contains an
alarm operation parameter for each of the two alarms associated with the LEDs on the
front panel of the 16C, 18C, and 25C controllers.
For each alarm there is also an alarm action parameter. This parameter is the first in
the alarm menu for each of the two alarms, and is used to specify how the alarm will be
used. The choices are:
• off – The alarm will not be used.
• normal – The alarm will light the LED when the alarm state occurs and turn
off the LED when the alarm state has cleared.
• latching – Once the alarm lights the LED, the LED will remain lit until the
operator presses the key, even if the alarm condition has cleared before
the operator presses the key.