Hi Patrick,
Which way to do you want to go? Do you want Show Control to trigger a button in DashBoard, or do you want Dashboard to trigger a button in Show Control?
If it's DB -> Show Control, I'm pretty sure that the Daktronics responds to rosstalk (TCP) commands. So you should be able to make a button that sends a rosstalk command, with a task like:
rosstalk.sendMessage(10.1.2.3, 7788, "GPI 31");
Where 10.1.2.3 is the IP address of the Dak, and 7788 is the port it's listening on. I don't have show control installed here, so I can't confirm.
#DashBoard