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Percentage change in item value that causes subscription callback


You configure DeadbandPercent to a value between 0 and 100. The default value is 0, which specifies that any value change will update the OPC server's cache. A non-zero value results in the cache value being updated only if the difference between the cached value and the current value of the item exceeds

DeadbandPercent * (High EU - Low EU) / 100

The DeadbandPercent property only affects items that have an analogue data type and 'High EU' and 'Low EU' properties defined (Property IDs 102 and 103 respectively). You can query data types and item properties using serveritemprops.


OPC servers may not implement the DeadbandPercent property behavior, even for values that have High EU and Low EU properties defined. For servers that do not support DeadbandPercent, an error will be generated if you attempt to set the DeadbandPercent property to a value other than 0.

DeadbandPercent is applied group wide for all analog daitem objects, and is used to prevent noisy signals from updating the client unnecessarily.




Applies to


Data type



Any value from 0 to 100, inclusive. The default value is 0.

See Also