Deadband (percent)
A percent deadband expresses the threshold as a percentage of the item's EURange span, so 1.0 on a 0 to 200 bar range means 2 bar. It requires the node to expose an EURange property. Without one the server cannot compute the band, and it either rejects the filter with BadDeadbandFilterInvalid or accepts it and reports every change.
The arithmetic
The threshold is DeadbandValue percent of EURange.High minus EURange.Low - the span - not a percentage of the current value. On a 0 to 200 bar range, 1.0 percent is 2 bar at 5 bar and 2 bar at 190 bar. That is usually what you want for instrumentation, where the noise floor scales with the transmitter span rather than with the reading.
EURange is the hard requirement
EURange is a Property of AnalogItemType Variables. Nodes typed as plain BaseDataVariableType - which is what most PLC-derived servers expose for ordinary tags - have no EURange at all, so a percent deadband on them has nothing to compute against. This is by a wide margin the most common reason a percent deadband appears configured and does nothing. Check the type definition first.
Why use it anyway
Because it scales. One rule - 1 percent of span - can be applied across every analogue tag in a plant regardless of whether it measures bar, degrees or millimetres, which an absolute deadband cannot do. On a server that models its analogue values properly with AnalogItemType, it is the right fleet-wide default; on one that does not, fall back to per-tag absolute deadbands.
Example
Same 1 percent request on two differently modelled nodes
Node A Pressure : AnalogItemType
EURange Low 0.0 High 200.0 span 200.0
DeadbandType Percent, DeadbandValue 1.0 -> threshold 2.0 bar works
Node B ns=3;s="Line3"."P_raw" : BaseDataVariableType
no EURange property
DeadbandType Percent, DeadbandValue 1.0 -> BadDeadbandFilterInvalid,
or accepted and silently inert
Verify by measuring the notification rate, not by reading the create response.Defined in: Part 4 - Services, DataChangeFilter and DeadbandType; Part 8 - Data Access for AnalogItemType and EURange.
Last verified 7 September 2026 against OPC UA 1.05.07. OPC UA Connect is an educational resource and is not affiliated with the OPC Foundation.