Behavior - Allen-Bradley 1444-TSCX02-02RB User Manual

Appendix A CIP Objects
454
The following are examples of hysteresis:
• An (over) threshold alarm of 10, hysteresis 10%, gives hysteresis
threshold at 9 (10% of the threshold, away from the threshold)
• An (outside) window alarm of 0 to 10, hysteresis 10%, gives hysteresis
thresholds at 1 and 9 (10% of the window range, away from each
threshold)
• An (outside) window alarm of -10 to 10, hysteresis 5%, gives hysteresis
thresholds at -9 and 9 (5% of the window range, away from each
threshold)
Source Selection
The ID is an index value that references a bit array to indicate the selected
measurement. See Measurement ID Definition on page 325

Behavior

An instance of the Measurement Alarm Object is used to assign alarming
behavior to a selected measurement.
The source measurement can be selected from any one of the measurements
that the module makes available.
The different instances are used to include various measurements in the alarm
scheme. Alternatively, multiple instances can refer to the same measurement
where multiple behaviors are required (differing thresholds as an example).
Once the measurement alarm instances have been defined, they are available to
use in the Voted Alarm Object. Then logical combinations of up to four
measurement alarms can be defined.
The alarm type, the measurement alarm behavior that pertains to transducer
status (TX OK), determines how TX OK state is integrated into the voting
logic. When you consider just the individual measurement alarm contribution
to the voted alarm or the simplest voted alarm logic, 1oo1:
• TX OK Considered - Alarm IF ([Measurement in alarm] AND [TX
OK])
• TX OK Monitored - Alarm IF ([Measurement in alarm] OR [TX Fail])
• TX OK Not Considered - Alarm IF [Measurement in alarm]
The enabled outputs of the Voted Alarm Object provide the 'actual alarms' that
can be assigned to relay outputs.
Rockwell Automation Publication 1444-UM001D-EN-P - June 2018
for further detail.