Tag Properties: Parameters
- Alarms Properties
- History Properties
To configure these properties for a tag, click Properties on the Home tab of the ribbon. A Tag Properties dialog displays, similiar to the following:
Use the parameters on this dialog to configure the different tag properties. Instructions for configuring each type of tag follows.
String-Type Tag Parameters
- Retentive Value checkbox: Click (check) to save the tag value continuously in case the system unexpectedly shuts down, so that it restarts from the last saved value.
- Retentive Parameters checkbox: Click (check) to save runtime changes in the tag’s properties. Only certain properties can be saved; for a complete list of which can and cannot, see List of tag properties.
CAUTION:Enabling either of the Retentive options for tags that frequently change values can cause heavy disk access, which slows performance.
- Startup Value field: Type a tag value for the system load. The tag assumes this value if you disable the Retentive Value option.
- Unit field: Type any string (up to 9 characters) as a brief description or reference. This tag is accessible during runtime.
Integer and Real-Type Tag Parameters
- Engineering Units area
- Min field: Specify a minimum value for the tag in engineering units. This tag is accessible during runtime.
- Max field: Specify maximum value for the tag in engineering units. This tag is accessible during runtime.
- Unit field: Type any string (up to 9 characters) as a brief description or reference of the tag. This tag is accessible during runtime.
- Signal Conditioning area
- Dead Band checkbox: Click (check) to insert the dead band value of a tag. Dead band value is a variation around a central value of the tag, which is not recognized for alarms.
- Smoothing checkbox: Click (check) to reduce the rate of change for the tag’s values. Use only for integers and real tags. For example, if you select the Smoothing option for the LEVEL1 tag containing the value = 50. Then in the next search, if the LEVEL1 changes to 60, the system will store the average of 50 + 60 in the database, so the new value = 55.