National Instruments BridgeVIEW How Do You Keep an Alarm Unacknowledged after the Alarm Returns to Normal?

Chapter 3 Tag Configuration

This type of situation clogs event files with redundant information and

can cause operators some frustration in having to acknowledge alarms

constantly when the tag has not changed significantly. You can use the

Alarm Deadband to alleviate this problem.

For the tag to go into alarm, it must go above the exact Alarm Value (in the

above example, 40). However, to be considered normal again, it must leave

the Alarm Value by an amount greater than the Alarm Deadband. For

example, if the range is 0 to 100 degrees Celsius, an Alarm Deadband of

1.0% (one degree Celsius) eliminates unnecessary events. Table3-9 shows

examples of events with Alarm Deadband set to 1.0%.

How Do You Keep an Alarm Unacknowledged after the Alarm Returns to Normal?

While editing a tag, select the Alarm Acknowledgement Mode ring and

choose either Auto Ack on Normal or User Must Ack.

With this option enabled, when a tag returns to normal state, the alarm

is automatically acknowledged. A message is logged to the event file if

event logging is turned on for the tag. By default, Auto Ack On Normal

is enabled.

9:15:15 40.1 Yes HI

9:15:20 38.5 Yes Normal

Table 3-9. Events with Alarm Deadband = 1.0%

Time Val ue Event Alarm Type

9:15:05 40.1 Yes HI

9:15:10 39.9 No HI

9:15:15 40.1 No HI

9:15:20 38.5 Yes Normal

Table 3-8. Events with Alarm Deadband = 0.0% (Continued)

Time Val ue Event Alarm Type