Next, a controller receives a signal that indicates {HEAD ~ the actual temperature} of {TAIL ~ the heating element} along with an indication of the desired temperature 
Next , a controller receives a signal that indicates { HEAD ~ the actual temperature } of { TAIL ~ the heating element } along with an indication of the desired temperature
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH