Configure value alarms

A value alarm is associated with integer or real tags. You can set alarms when the tag value transitions from a set of predetermined thresholds that range from LoLo to HiHi. You can configure whether the alarmed state corresponds to any value of the tag and the associated priority of that alarm.

Configure a value alarm

1. Open the Tagname Dictionary.

2. Select an existing real or integer tag or create a new tag.

3. Select either Alarms or Details & Alarms at the top of the Tagname Dictionary dialog box to show the alarm details dialog box.

   

4. In the ACK Model area, select the alarm acknowledgement model for the tag.

   • Select Condition for acknowledgment to count against all transitions into the alarmed state or a sub-state up to the time of the acknowledgement. This is the default acknowledgement model.

   • Select Event Oriented for an acknowledgment to only be for a particular transition to the alarmed state or a sub-state. An acknowledgment is accepted only if it refers to the most recent transaction.

   • Select Expanded Summary for acknowledgment to only be for a particular transition, whether to an alarmed state, to a sub-state, or a return to normal. Each transition from the normal state marks the beginning of a new "return to normal" (RTN) group. All transitions in an RTN group must be acknowledged individually before the overall RTN group is considered acknowledged.

5. In the Alarm Comment box, type a default comment up to 131 characters. The comment is assigned to the tag’s .AlarmComment dotfield.

   Note: The Alarm Comment box should not contain the double-quote character ("). A process that uses the double-quote as a delimiter will fail if it is fetching an alarm comment that includes a double-quote.

6. Select the alarm types (LoLo, Low, High, HiHi) to detect when the value of the tag is beyond an absolute limit.

7. In the Alarm Value boxes, type the limit values for the alarm types.

   For example, in the case of LoLo and Low alarms, an alarm condition exists whenever the value of the tag is less than the Alarm Value. In the case of High and HiHi alarms, an alarm occurs whenever the value of the tag exceeds the Alarm Value. You can use real numbers for the limits.

8. In the Value Deadband box, type the number of engineering units the tag value must drop below or above the alarm value before it transitions out of an alarm state.

   For example, to return-to-normal from an alarm condition, a tag value must not only return inside its alarm limit, but also return through your specified Value Deadband. The Value Deadband prevents nuisance alarms caused by repetitive re-annunciation of an alarm where the tag value hovers around the limit, continually fluctuating in and out of an alarm state.

9. Optionally assign an alarm inhibitor tag for the tag’s alarm types (LoLo, Low, High, HiHi).

   1. In the Alarm Inhibitor area, select the button to show the Select Tag dialog box containing a list of defined tags.

   2. Highlight a tag in the list and select OK. The name of the tag you selected as the inhibitor tag appears in the Alarm Inhibitor box.

   For more information on inhibitor tags, see Inhibit alarms.

10. Select Save.

11. Select Close to exit the Tagname Dictionary dialog box.