Micromod MOD: Modcell 2050R Users Guide - Manual (Page 156)

IB-23C650
BASIC OPERATION
When the alarm finally stops, the alarm indicator will go out. If there is an
alarm at one limit that has not been acknowledged (e.g. HI), and then the
process subsequently trips the alarm at another limit (LO, HI-HI, or LO-LO),
only the highest priority unacknowledged alarm will flash. If the low alarm
remains when the alarm is acknowledged, the high alarm will extinguish and
the low alarm will assume a steady-on condition. Priorities are: diagnostics
(1), priority 1 (2), priority 2 (3).
Acknowledgment of an alarm does not change the alarm output (relay state).
The alarm output follows the alarm state; it turns on when the alarm is tripped
and turns off when the alarm state ceases.
Alarms with Acknowledgment and Latch
The controller can be set up so the alarm output (relay) will remain on until the
alarm has been acknowledged even though the alarm condition may have
ceased to exist. The only way an alarm output can be turned off is to
acknowledge the alarm condition. This feature is enabled in the ALARMS
MENU and is called “P1 RELAY ACTION” or “P2 RELAY ACTION“ for priority
level 1 or 2 alarm latching. “NO LATCH“ causes the alarm output to follow
the alarm condition, i.e. the alarm output releases when the alarm ceases.
“LATCHING” requires the alarm be acknowledged even if the alarm condition
ceases to exist.
Alarm Acknowledgment Procedure
Alarms are acknowledged in the DISPLAYS MENU. To acknowledge an
alarm, press the alarm key. The process display will indicate the alarm type
(e.g. AL1 HOP) and the lower engineering display will show [UNACKED].
Press the up key to acknowledge the alarm. Note the lower engineering
display shows [ACKED] to indicate the alarm has been acknowledged. Repeat
this procedure for all active alarms, pressing the alarm key to scroll through
the alarms. If the digital input has been enabled as a global alarm
acknowledgment, a contact closure or voltage less than 1.5Vdc will
acknowledge all alarms.
Alarm Type Messages
Alarm type messages that appear when scrolling through the list with the
ALARM key are: AL1 HPR (process high), AL1 LPR (process low), AL1 HDV
(deviation high) AL1 LDV (deviation low), AL1 HI2 (input 2 high), AL1 LI2 (input
2 low), AL1 HOP (output high), and AL1 LOP (output low). Process alarm 2, 3
and 4 are the same.
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