Deadbands

Alarm deadbands control the sensitivity of the high and low alarms.These alarms are always triggered when the value being monitored crosses the High or Low limit. The value that causes the alarm state to end depends on the configured deadband.

When the record is in the High alarm state, it remains in that state until it drops below the High limit minus the deadband, as shown in the figure below. These conditions prevent minor fluctuations from repeatedly putting the value into and out of the alarm state. Similarly, when a record is in the Low alarm state, it remains in that state until it rises above the Low limit plus the deadband. If the deadband is set to 0, this feature is disabled. These deadband rules apply in the same manner to all of the limits.

Advanced Database Editor (ADE) validation rules ensures that bad configurations cannot be entered. The rules are:

• High must be greater than Low for at least deadband value for that level.

• High-High must be greater than High for at least the High-High deadband value.

• Low-Low must be less than Low for at least the Low-Low deadband value.