Rockwell Automation FactoryTalk Alarms and Events Quick Start - Manual (Page 183)

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Appendix B
System performance and limits
FactoryTalk Alarms and Events has been tested to conform to the following
performance limits.
Controller specifications
Execution times for alarms
Scan times increase more during a scan when many alarms change state at the same
time.
An alarm state change is any event that changes the condition of the alarm. To
minimize the potential for large alarm bursts, create dependencies on related alarms.
Large alarm bursts can have a significant impact on the scan time of application code.
Specification Value
Number of subscribers (RSLinx
Enterprise servers) per controller 16
Controller memory used for buffering by
each subscriber (RSLinx Enterprise) 100KB
Typical number of alarm state transitions
per subscriber 1000
Recommended maximum number of
alarms per controller 2000
Approximate controller memory used for
each alarm Digital 1 KB; Analog 2.2 KB; Using
associated tags, string tags consume 750-
1600 bytes per string tag depending on
the alarm type.
Supported languages for alarm messages All languages supported by FactoryTalk
View.
Rung State Execution times
ALMD instruction ALMA instruction
False with no alarm state
change 8 μs 17 µs
False with alarm state change 35 µs 17 µs
True with no alarm state
change 8 µs 65 µs
True with alarm state change 35 µs 126 µs