It appears that it constantly scans. I have printed a circuit, (with the help of other members() that you push a button, goes to limit switch, then returns to home position. Is it alright to use limits or do you need to operate strictly by pulse numbers, If you can use photo-detector or micro switch and s-r latch to rotate and and s-r latch to start and stop system. so when each limit is reached it either sets or resets the latch to 0 0r 1. If you use puses the problem I see is you still need a home limit switch to reset the system, say you powered off in the middle of cycle the stepper will have no idea where it is? or you could use mechanical stop I suppose? p.s I did modify the origanal design, only by adding to it....
so on an original note...... I see no reason why you cannot use the IC you specified by putting them in series...... then at the end of each cycle switch the next the next one on, then the next one, then switch states, hten cycle again.....