If can be any comfort for you. You are not the first doing this kind of mistake;). Then I am working with with a unknown/new instrument. I have made it a habit to always make my test program so close up to data sheet a possible. If it specify bytes I send bytes, and if they are documented in hex I use that format. Later then I know the protocol basics I can change the format. I have wasted some hours by dumb errors. Like be 100 percent sure a string is set to hex display then it is not sigh!
Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)