Mitsubishi Electric MELSEC iQ-R Series User Manual page 124

Alarm Cancel Notification
The SECS/GEM communication software may be affected when a large number of alarms occur at the same time.
To prevent this, the SECS/GEM communication software cancels alarms when 33 or more alarm reports are sent at the same
time. Even when the number of alarm reports is 32 or less, alarm reports are canceled when the sending queue becomes full
before all sending is finished.
With regard to canceled alarm reports, sending is started again by switching the alarm occurrence (or alarm recovery) trigger
to ON, and the report cancel notification relay is switched OFF when all reports are completed.
In addition to the interlock of the alarm status register, a lock by the ladder program is necessary so that recovery processing
is not performed until all alarm occurrences are completed when alarms are canceled during alarm occurrence processing.
Similarly, a lock is used to prevent occurrence processing midway when alarms are canceled during alarm recovery
processing.
The following section shows the processing flow when 50 alarms have occurred.
Programmable
controller CPU
Alarm Processing Notification relay ON
Interruption Notification relay ON
Alarm occurrence trigger OFF
Alarm Processing Notification relay
OFF
(1)
Alarm Processing Notification relay ON
Interruption Notification relay ON
Alarm occurrence trigger OFF
Alarm Processing Notification relay OFF
(1) Locked by the ladder program so that alarm recovery processing is not carried out until all alarm report sending is complete
7 BASIC FUNCTIONS
122
7.9 Alarm Definition (non-GEM version)
SECS/GEM communication
software
Alarm Occurrence trigger ON
Alarm occurrence trigger ON
Scan status register
(50 Alarms occur simultaneously)
Send 32 Alarm reports
Secondary
(Reception of 32 secondary messages)
Scan status register
Send 18 Alarm reports
Secondary
(Reception of the remaining 18 secondary
messages)
Host