The flux sensors generate signals to indicate step movement and direction, and {HEAD ~ a digital comparator} compares {TAIL ~ the contents} of an up/down counter with the contents of a step command counter 
compares
The flux sensors generate signals to indicate step movement and direction , and { HEAD ~ a digital comparator } compares { TAIL ~ the contents } of an up / down counter with the contents of a step command counter
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH