Delete Objects

When you finish using your OPC Toolbox™ Data Access objects, use the delete function to remove them from memory. After deleting them, clear the variables that reference the objects from the MATLAB® workspace by using the clear function.

Note

When you delete an opcda client object, all the group and item objects associated with the opcda client object are also deleted. Similarly, when you delete a dagroup object, all daitem objects associated with that dagroup object are deleted.

To illustrate the deletion process, this example creates several opcda client objects and then deletes them.

Step 1: Create several clients

This example creates several opcda client objects using fictitious host and server ID properties.

da1 = opcda('Host1','Dummy.Server.1');
da2 = opcda('Host2','Dummy.Server.2');
da3 = opcda('Host3','Dummy.Server.3');

Step 2: Delete clients

Always remove toolbox objects from memory, and the variables that reference them, when you no longer need them.

You can delete toolbox objects using the delete function.

delete(da1)
delete(da2)
delete(da3)

Note that the variables associated with the objects remain in the workspace.

whos
  Name      Size                    Bytes  Class

  da1       1x1                       636  opcda object
  da2       1x1                       636  opcda object
  da3       1x1                       636  opcda object

These variables are not valid OPC Toolbox Data Access objects.

isvalid(da1)
ans =
    0

To remove these variables from the workspace, use the clear command.

Note

You can delete toolbox object vectors using the delete function. You can also delete individual elements of a toolbox object vector.