Deadband Shortcut Menu Option

Under certain circumstances, you might be required to enter a deadband value for an analog tag. A deadband value indicates to the system how much change is required in an analog value before a change in value is reported and logged. Because some analog values fluctuate very frequently, you may choose to set a deadband value. Data is not reported unless it has changed by at least the deadband amount.

To set or modify a deadband value for an analog tag:

1.  Right-click the graphic object representing the equipment process. The shortcut menu opens and displays the options available for the selected object.

2.  Select the Logging Deadband option of the shortcut menu. (Note: If you have not been granted the user privilege to disable alarms, the Disable Alarm (or Alarm Disable) option is disabled in the shortcut menu.) The Deadband dialog opens and displays the Logging Deadband field for the selected tag.

3.  Enter a deadband value (the units or fractions of a unit the value must change before the change in value is reported) in the Deadband field. The deadband value corresponds directly to the units in the Engineering Units field. For example, as displayed above, the deadband value is "0.5", and the configured engineering unit is "FT"; therefore, the deadband value indicates that the value of the equipment must change by half a foot before it is reported.

4.  Click the OK button. The Deadband dialog closes. You may see the Operational Changes Pending dialog box for a brief moment while the data is updated for the tag. Do not click the Cancel button; rather, wait for the dialog to close.

Once the tag is updated with the new deadband value, the tag does not report data unless the value has changed by at least the deadband amount.