Here's my problem: I'd like to create a schematic by giving the user a box of items (say circuit elements) that the user can drag and drop into place. The user could then set a property of the element, such as a COM port, and then a polling machine (separate) would say retrieve a value and display it in an indicator associated with the element.
I understand how to poll, say in modbus, and I understand event structures although I've only ever used them to detect a front panel click per the producer/consumer with events pattern. Any help in how to create a new control on the fly, as well as how to refer to it in order to update it regularly say, as well as how to drag and drop it, would be really appreciated!
Yeah you don't want to do that. The question as it is right now cannot be done on a VI that is running. Using Scripting you can programatically make controls but only on VIs not running, and only from the development environment, not in a built EXE. There are several other techniques that make it appear as if you are making new controls, none of which are very easy to implement and have other limitations.
Even so, the application you want sounds complicated and I think you need to get a good list of requirements before you start. It does not sound like a simple application and would take plent of time for debug and support.