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5.2.4.12 Process Alarms
A process alarm sets an absolute trigger level (or temperature). When the process (could be
PV1, PV 2 or PV1-PV2) exceeds that absolute trigger level an alarm occurs. A process alarm is
independent from set point. Adjust A1FN (Alarm 1 function) in setup menu. One of 8 functions can be
selected for process alarm. These are: PV1.H, PV1.L, PV2.H, PV2.L, P1.2.H, P1.2.L, D1.2.H, and D1.2.L.
When the PV1.H or PV1.L is selected the alarm examines the PV1 value. When the PV2.H or
PV2.L is selected the alarm examines the PV2 value. When the P1.2.H or P1.2.L is selected the alarm
occurs if the PV1 or PV2 value exceed the trigger level. When the D1.2.H or D1.2.L is selected the
alarm occurs if the PV1-PV2 (difference) value exceeds the trigger level. The trigger level is determined by
A1SP (Alarm 1 set point) and A1HY (Alarm 1 hysteresis value) in configuration for alarm 1. The hysteresis
value is introduced to avoid interference action of alarm in a noisy environment. Normally A1HY can be set
with a minimum (0.1) value. A1DV and/or A2DV are hidden if alarm 1 and/or alarm 2 are set with process
alarm.
5.2.4.12.1 Alarm Modes
One of 4 kinds of alarm modes can be selected for alarm 1 and alarm 2. These are Normal
alarm, latching alarm, Holding alarm and Latching/Holding alarm.
5.2.4.12.1.1 Normal Alarm: A1MD = NORM
When a normal alarm is selected, the alarm output is de-energized in the non-alarm condition
and energized in an alarm condition.
5.2.4.12.1.2 Latching Alarm: A1MD = LTCH
If a latching alarm is selected, once the alarm output is energized, it will remain unchanged even
if the alarm condition is cleared. The latching alarms are disabled when the power is shut off or if event input
is applied with proper selection of EIFN.
5.2.4.12.1.3 Holding Alarm: A1MD = HOLD
A holding alarm prevents an alarm from power up. The alarm is enabled only when the
process reaches the set point value ( may be SP1 or SP2 ). Afterwards, the alarm performs same
function as normal alarm.
5.2.4.12.1.4 Latching / Holding Alarm: A1MD = LT .HO
A latching / holding alarm performs both holding and latching function.
5-1 Normal Process Alarm
Page 141 of 479
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