Add and configure an OPC HDA variable

An OPC HDA variable item is an item that you add to an OPC HDA group. It represents a variable tag or data point on an OPC HDA server. A variable stores a scalar value that is compatible with an OLE DB variable value, which permits the use of OPC HDA variables and OLE DB variables in the same expression. AVEVA™ Production Management updates the OPC HDA variable items every time the OPC HDA Data Source polls the OPC HDA server and detects changes to the values of variables on the OPC HDA server.

You can add multiple variables to a project. Add a separate OpcHdaVariable item to the Project Explorer for each variable tag on the OPC HDA server that you want to use. You can map multiple OpcHdaVariable items to the same variable tag on the OPC HDA server.

Prerequisite

Add an OPC HDA group before adding a variable.

Guidelines

Use this procedure to add one variable at a time. If you want to import one or more variables simultaneously from an OPC HDA server, use the OPC HDA variables configuration tool.

When you add one variable at a time, AVEVA Production Management initially gives the OpcItemID property and the Name property of the variable the same value. If you do not change the value of the OpcItemID property; that is, it still contains the same value as the Name property, changes to the Name property cause AVEVA Production Management to give the OpcItemID property the same value.

To add an OPC HDA variable

1. In the Project Explorer, right-click the group, and then click Add Variable. An OpcHdaVariable appears.

   

2. Rename the item with a meaningful name.

3. Configure the properties. For guidance in configuring the properties, see OPC HDA variable properties.

Related topics

• Use the Project Explorer

• Add and configure an OPC HDA group

• About the OPC HDA variables configuration tool