Technical Reference Manual - InduSoft

Tags and the Project Database
From the Tag Properties dialog, specify integer and real-type parameter properties as follows:
• 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.
Boolean-Type Tag Parameters
Note: For descriptions of these parameters, see String-Type Tag Parameters above.
See also: Using Tag Properties: Alarms, Using Tag Properties: History
Using Tag Properties: Alarms
Use the Tag Properties dialog to view the configured alarms for a selected tag. IWS disables this command
if there are open alarm worksheets. Before using these dialogs, you should have already created the alarm
groups.
ALARM TYPES:
• HiHi: A Very High alarm is present.
• Hi: A High alarm is present.
• Lo: A Low alarm is present.
• LoLo: A Very Low alarm is present.
• Rate: An alarm based on rate of change is present.
• Deviation: An alarm based on deviation from a given set point is present. Example:
• If SetPoint = 50, Deviation + = 5, Deviation − = 5, and Deviation Dead Band = 0.5;
• IWS generates an alarm when the temp ≥ 55 or temp ≤ 45; and
• A return to the normal occurs when temp ≤ 54.5 or temp ≥ 45.5.
ALARM LIMITS:
• HiHiLimit: When creating Very High alarms in the Tag Properties dialog, use this field to specify the limits.
You can access this field during runtime and use it during modifications on the fly.
• HiLimit: When creating High alarms in the Tag Properties dialog, use this field to specify the limits. You
can access this field during runtime and use it during modifications on the fly.
• LoLimit: When creating Low alarms in the Tag Properties dialog, use this field to specify the limits. You
can access this field during runtime and use it during modifications on the fly.
• LoLoLimit: When creating Very Low alarms in the Tag Properties dialog, use this field to specify the limits.
You can access this field during runtime and use it during modifications on the fly.
• DevSetpoint: Reference point for a tag value deviation that triggers an alarm. Define the alarm message in
the Tag Properties dialog or on an Alarm worksheet. You can access this field during runtime.
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