Tom Easterday wrote:
> Thanks Jeff and Stephen.  We were thinking of using it for home.  So, if the 
> index pulse is going to be different each time, then how do physical limit 
> switches work any better?  It is a digital input, no?
>    
Right - it will work just as well as a switch, but probably with better 
precision (assuming that the switch you use for the first home contact 
has a trip range that's significantly smaller than the distance moved 
with one revolution of the screw).

You can choose the second home velocity based on the speed you can see 
the index and the accuracy you want.  For example, assuming that you 
want to home to within 0-3 counts of the index, you can move at 4 counts 
per servo cycle (ie, 4000 counts/second) for the index-finding move.  
That will guarantee that the servo cycle is never more than 3 counts 
away from the actual edge.  You still need to use an edge component to 
stretch the pulse, as Jeff suggested.

- Steve


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