Drag and drop works, you’re not doing anything wrong really, but when using this “Service Interface” mechanism in the S7-1200 we’re not able to read structures.
Another thing I will mention, since I missed that this was a S7-1200, is that via the “Server Interface” mechanism Ignition will not be able to read whole structures, only individual exposed structure members. I can’t remember if the 1200 exposes these or not, but it’s not ideal performance-wise for the PLC.
This is because the 1200’s Service Interface mechanism only supports the newer DataTypeDefinition attribute, and not the older DataType Dictionary mechanism, that let’s clients learn about …