​Thanks again Christof for pointing me in a promising direction.  I have been working with the OSC tagging via slipenc and slipdec.

As of now I have fairly reliable communication between PD and the Arduino sketch using a version the patch you provided.  I am able to reliably send messages and the sketch responds as I expect most of the time.  However, when sending several faders simulaneously I get some glitching.  Right now I am wondering if it has something to do with using OSC instead of the raw slip packages.  I do get this message in the pd console but I'm not sure that it relates to the glitching: "slipdec: input packet longer than 1006"