Hi J-M-L,
Thanks. I'll give itoa() a shot. Data manipulation is not my strong suit in software. Getting ASCII for the GPS/GSM module was a pain in the butt.
Yes, turns out the case #s are not the problem. 0,1,2 or 3,4,5, I was doing more testing last night and I believe the problem is the 700mS period needed to clear the error registers in the MAX31865s. I pared the code down to just 1 chip (of 3), and I could see the GPS results come dribbling in one character at a time when I spread out the GPS location requests to a minute or two between requests (vs 15 seconds) and eventually the entire string was read in and flow proceeded normally. With 2 chips even more time was needed, and with 3 it got ridiculous. So now I am in the process or rewriting the code blink-without-delay style to let everything else run normally while waiting for one to clear out and then the 2nd to clear out. It's a little awkward as they occur in an else{ } statement after a sample is requested, but I'll get it figured out.