•Motor position 1 is read and written to value B in a math block
•Motor position 2 is read after a 0.1 second delay, is written to value A in a math block
•Math block subtracts value B from value A (in degrees)
This sounds very boring until you start thinking of possible applications for detecting a stalled motor. The most obvious one is a car (or tank) that goes in reverse and turns every time it comes up against a wall and the wheels stall.
The more interesting application is the detection of end-of-travel. By detecting the travel limits of a mechanism, you can now home (position to a starting point) any machine.
The detection parameters (time between measurement A and B and expected travel) will vary by machine