Rockwell Automation 9301 Series RSView32 Users Guide - Manual (Page 130)

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RSView32 User’s Guide
You can specify whether or not to generate alarms when an analog tag
value is moving back to normal operating range and recrosses the
alarm trigger threshold. If you choose to generate alarms when the
motor is moving back towards normal operating range, an alarm
would be triggered when the motor speed falls below 5,000 rpm and
4,000 rpm, and when it rises above 1 rpm and 1,000 rpm. If you don’t
want to generate these alarms, make sure “Generate alarms when
approaching normal operating range” is deselected, in the Setup tab of
the Alarm Setup editor.
Variable thresholds
Threshold values can be constant or variable. The above example uses
constant thresholds. A variable threshold can change, because its value
is taken from another tag value, not a constant number. You define a
variable threshold by naming a tag in the appropriate field in the
editor. That tag’s value is the threshold for the alarm; as the tag
changes, the threshold changes.
Variable thresholds require more system resources than constant
thresholds. This is due to the continuous scanning of threshold values
and to the processing necessary to detect alarm faults.
falls below 2,000 rpm 8
falls below 1,000 rpm 6
falls below 1 rpm 4
* These alarms are triggered only if “Generate alarms when approaching nor-
mal operating range” is selected in the Alarm Setup dialog box.
If the motor speed It triggers an alarm of this severity