Micromod MOD: Modcell 2050R Users Guide - Manual (Page 153)

IB-23C650
BASIC OPERATION
combination of the four display alarms. Monitoring and acknowledging alarms
are basic operator activities. Acknowledgment of alarms may or may not be
required depending on the alarm set up in the ALARMS MENU. During
power-up the alarm relay(s) remained powered down until an accurate process
input reading was made. Relays selected as alarms will be in a fail-safe
condition (powered when alarm is not active) until the alarm is active. See
Figure 16 for display and relay operation under different alarm conditions.
Figure 16a. Controller Alarm Display and Relay Status Conditions (Sheet 1)
S-1107-291A(1)
(Sheet 1 of 2)
Alarm Ceases
ALARM STATUS WITHOUT ACKNOWLEDGMENT
(No Relay)
Alarm Occurs
Normal Operation Alternating Process Variable*
and Alarm Message
Alarm LED Flashes
ALARM STATUS WITH ACKNOWLEDGMENT
(No Relay)
Alarm Ceases
Alarm Occurs
ACK’d Alarm
Ceases
Alarm Ceases
before ACK
Steady Alarm LED
Alternating Process Variable*
and Alarm Message
Alarm LED Flashes
ACK’d Alarm
still exists
Normal Operation
ALARM AND RELAY STATUS WITHOUT ACKNOWLEDGMENT
Alarm Ceases
Alarm Occurs
Normal Operation,
Relay Energized
Alternating Process Variable
and Alarm Message,
Relay De-energized
* or TAG & DIAG message if
it is a diagnostic alarm.
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