ROC Alarms
- Last UpdatedNov 15, 2022
- 3 minute read
Select the Attribute you want to configure in the Attributes List, then click ROC Alarms in the configuration pane to add the Rate of Change Alarms Feature to the Attribute. Use the following table to configure the ROC Alarms feature.
|
ROC Alarms Option |
Associated Attribute |
Description |
Run-Time Access (Supervisory, User, Read- Only, None) |
|---|---|---|---|
|
Rate of Change alarm feature |
ROCAlarmed |
If enabled, alarms will be triggered when the Attribute level reaches the configured rates of change. |
None |
|
Up |
ROC.IncreasingHi.Alarmed |
If enabled, an alarm will be triggered when the Attribute value is increasing too fast. |
None |
|
Up - Limit |
ROC.IncreasingHi.Limit |
The alarm limit that the rate of change calculation must exceed in order to trigger an alarm. |
Supervisory, User |
|
Up - Priority |
ROC.IncreasingHi.Priority |
The value for the urgency of the alarm. Valid values are 1 through 999, with 1 being the most urgent. |
Supervisory, User |
|
Up - Alarm message |
ROC.IncreasingHi.DescAttrName |
The name of the attribute (within the same object) to be used as the alarm message. The attribute you specify must be of type String or InternationalizedString, with a maximum string length of 329 characters. If no attribute is specified, the Attribute description is used as the alarm message. Click the ellipse button to access the Attribute Browser. |
Supervisory, User |
|
Down |
ROC.DecreasingHi.Alarmed |
If enabled, an alarm will be triggered when the Attribute value is decreasing too fast. |
None |
|
Down - Limit |
ROC.DecreasingHi.Limit |
The alarm limit that the rate of change calculation must exceed in order to trigger an alarm. (This value, although a positive value, actually indicates a negative rate of change, or a descending rate of change Hi limit.) |
Supervisory, User |
|
Down - Priority |
ROC.DecreasingHi.Priority |
The value for the urgency of the alarm. Valid values are 1 through 999, with 1 being the most urgent. |
Supervisory, User |
|
Down - Alarm message |
ROC.DecreasingHi.DescAttrName |
The name of the attribute (within the same object) to be used as the alarm message. The attribute you specify must be of type String or InternationalizedString, with a maximum string length of 329 characters. If no attribute is specified, the Attribute description is used as the alarm message. Click the ellipse button to access the Attribute Browser. |
Supervisory, User |
|
Changes per |
ROC.Rate.Units |
The units of time for the rate of change calculation. |
Supervisory, User |
|
Evaluate every |
ROC.EvalPeriod |
The time interval, in milliseconds, at which the rate of change calculation and detection is performed. |
None |
ROC alarms are used to detect and report a condition when the Attribute value increases or decreases at too fast a rate. You can specify a limit for both the increasing and decreasing directions. For the increasing limit, if the Attribute value increases at a rate greater than the limit, an alarm is generated. Similarly, for the decreasing limit, if the Attribute value decreases at a rate greater than the limit, an alarm is generated. The limit value in either case is a positive number.
In addition to specifying the rate limit value, the time dimension for the rate must be specified depending on the time dynamics of the variable being measured. The choices are per second, per minute, per hour, and per day. For calculation of the rate itself, the time interval at which the rate (or slope between points) is calculated is also specified as a time interval in milliseconds.
For example, if you want to put a rate limit on the rate at which a number of gallons accumulates in a tank at 200 gallons per minute, and you want to specify the calculation to be performed every 5 seconds, then specify:
-
IncreasingHi.Limit = 200
-
Rate.Units = Min
-
EvalPeriod = 5000