Description
The Interpolation Type for the tag. This property applies to analog tags. The Interpolation Type determines how retrieval determines which analog value to return at a given cycle boundary. Valid values for a tag are as follows:
| Value | Name | Description |
|---|---|---|
| 1 | Linear | Linear interpolation is used. The Historian calculates a new value at the cycle boundary by interpolating between the last stored value before the boundary and the first stored value after the boundary. If either of these values is NULL, the historian returns the last stored value before the boundary. |
| 255 | None | Indicates that no Interpolation Type override, either Stairstep or Linear, is used. The Interpolation Type setting for the tag is used. |
| 0 | StairStep | Stair-stepped values are used (as in normal cyclic retrieval). No interpolation occurs. The value at the cycle boundary is assumed to be the same value as the last stored value before the cycle boundary. The last known point is returned with the given cycle time. If no valid value can be found, a NULL is returned. |
| 254 | SystemDefault | The setting of the InterpolationTypeInteger or InterpolationTypeReal system parameter is used. |
If you create a metadata field for this property, then an error will occur if you set the field to an invalid value for this property. HCAL will not export data for that point or accumulator.
Geo SCADA Expert Metadata Field
WH_TagInterpolationType
Default Value
The default value is SystemDefault.
Type
Long.