Change Rate Alarm Calculation

The Change Rate alarm calculation uses the CHANGE_RATE alarm calculation and can only be implemented with the CygNetEnhanced Point Scheme. On each update, if the point value changes more than the maximum allowed times for a given interval, the system will set the alarm bit. See Understanding the CVS Metadata File for more information about the elements and attributes that define the CygNet Enhanced Point Scheme.

For more information, see Alarm Calculation Types.

The following image shows the area of an Analog Alarm Settings page of a PNT Editor with an enabled Change Rate.

Calculation Parameter

• Maximum Changes (calcparm1) — maximum allowed number of change within the time interval before the alarm bit is set
• Time Interval (sec) (calcparm2) — time interval in seconds

• If update count > maximum allowed number of changes, alarm is set.
• If update count ≤ maximum allowed number of changes, alarm is not set.

Example

• calcparm1 = 2
• calcparm2 = 60

In this example, the Change bit is set because the number of changes (3) within the time interval of 60 seconds is greater than the maximum allowed number of changes (2).