It looks like you will have a conflict if your WHILE loop is going to start reconfiguring your ouput pin before you have time to receive a response.
It would be pretty hard to get any sense out of that one without putting at least some kind of delay in to both see a response and tell what it was.
Also, in the upper vi I think you should continue the ouput of the arduino resource for good measure.
And also carry the resource and error lines in your pinging vi within the loop to the loop wall and close.
Right now I think you are close... the vi is running around in circles not waiting for a response while the arduino is perhaps flailing around changing inputs to outputs and vice versa...
Your LIFA code should be setting your inputs and ouputs for the chosen pin and waiting for the response.
Tim
Will send you something when I can actually send email out the door.
