The best way to debug any product file is with the "Watch" window and "Live Log". In the "Watch" window, just add the device's name (just the name by itself). It is also helpful to add your show controller to the watch list as well.
Then, open the "Live Log" and you be able to see all messages going back and forth between your show controller and your specified device.
An example would look like...
If the device is TCP, you should also add the device's ".TCPStatus" variable to the Watch window.
Now you can examine if there is an error in the ascii or hex characters being sent back and forth by comparing it to your device's external communication protocol documentation.
If you don't have access to the V16Pro, you can use the "Product File Tester" from the "Tools" menu in WinScriptLive to look at the outgoing strings.