Deadband Control Tag Type Properties: Options Tab
The Options tab of a deadband control tag's properties folder enables you to select the tag whose value will be monitored, and to configure details such as whether the control is enabled and whether it will send a start signal when the monitored value goes above or goes below the setpoint.
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This should be either a tag, or an expression based on one or more tag values. While Constant is available as an option due to the nature of this field selector, it will not be useful as a monitored value.
The deadband control compares the Monitored Value with its low and high setpoints to determine its own value. If the Monitored Value is less than the value of the Low Setpoint, then the value of this deadband control tag will be 1. If the Monitored Value is greater than the value of the High Setpoint, the value of this deadband control tag will be 0.
Note: The behavior of this deadband control tag can be reversed such that if the Monitored Value is greater than the value of the High Setpoint, the value of this deadband control tag will be 1 using the Operation radio buttons (see below).
The effect of setting the inhibit flag is to force the tag’s value to be 0, regardless of other settings.
A valid value for the Inhibit field can be provided via any of a constant, an expression, or a tag. Please see Constant, Expression or Tag for help selecting which to use.
The Operation section contains two radio buttons that enable you to set the behavior of this tag.
Start On High: If the Start On High radio button is selected, the value of this tag will be reversed from its default. When the Monitored Value is greater than the High Setpoint (see Deadband Control Tag Type Properties: Setpoints Tab), the value of this deadband control tag will be 1 (rather than 0, which is the default).
Start On Low: If the Start On Low radio button is selected, if the Monitored Value is less than the Low Setpoint (see Deadband Control Tag Type Properties: Setpoints Tab), the value of this deadband control tag will be 1.
The Manual Data property enables you to set a user-defined value for this tag. If the value of the Manual Data field is left Invalid, or is not a valid number, then the value for this tag is read.
Note: If the value entered into the Manual Data field is a 0, the actual value of this tag is also overridden, as 0 is considered a valid value. Therefore, you must clear the Manual Data field entirely if you wish the actual value of this tag to be read, rather than a manually-entered value.
Questionable data is a means of indicating that the data being reported by a tag might not be accurate. Use this field to flag the tag’s data in the event that you suspect the values it is reporting might not be accurate, or when this tag has initially been created and you wish to ensure that its data is marked for extra monitoring.