OPC HDA variable properties

SampleTypeCode

The data type of the sample stream for the variable. The data type must be compatible with the data type of the variable being mapped to on the OPC HDA server.

For more information, see Configure the DataType property for fields.

Boolean, DateTime, Double, Event, Int32, Int64, Single, String

Value

The value of the last sample written to the historical stream of samples.

AVEVA™ Production Management usually reads the variable tag on the OPC HDA server to derive the value; however, you can also change the value of the OpcHdaVariable item directly with the Value property, or by the execution of running code.

AVEVA Production Management writes the changed value back to the OPC system immediately, and updates the OpcHdaVariable item sample after the next event notification.

OpcItemId

The tag name of the variable on the OPC system that the OpcVariable item maps to.

The OpcItemId property is case-insensitive, and it keeps the name of the variable tag on the OPC HDA server separate from the name in the Name property.

When you add an OpcHdaVariable item with the Add Item menu command of the OpcHdaGroup item, rather than with the OPC HDA variables configuration tool, AVEVA Production Management initially gives the OpcItemId property and the Name property the same value. Changes to the Name property cause AVEVA Production Management to update the OpcItemId property with the same value.

A match of the tag name on the OPC HDA server