Kirk Wallace wrote:
> 
> This clears up allot. I hooked up the position signal to B and the index
> signal to Z. I got 0 1 0 1 0... on count with halmeter but no indication
> from halmeter on the index or index-enable. Is the index update also
> dependent on the quadrature signal?
> 
The 0 1 0 1 is exactly what you get when there are pulses on 
only one quadrature input.  Index-enable will only go true 
during a home or spindle-sync operation, so that is normal.
The encoder index signal, in this case ppmc.0.encoder.xx.index
should still show narrow pulses even with no quadrature.  Note 
these pulses will normally be only one sample wide, so that's 1 
millisecond at default servo update rate.

>>First, here's what I'd do, is connect the pulse output to the 
>>UPC's A encoder input, and connect a 10 K Ohm resistor between 
>>the A and B encoder inputs.  Then, connect a .01 uF capacitor 
>>from the B input to ground.  This will create a 100 us delay 
>>between A and B, which should satisfy the counter as a valid 
>>quadrature pattern.
> 
> 
> Very clever. I'll have to play with this. Though, just for fun, I'll
> take a stab at the numbers. Let's say I want to run the spindle at 3k
> rev./min. with a 2k pulses/rev. encoder. This gives 6m pulses/min. or
> 100 kHz or 10 us? If that is right, then I would have encoder problems
> at higher speeds?
> 
OK, I didn't expect this one-channel gadget to be so high 
resolution.  Just reduce the value of the capacitor or resistor 
to reduce the delay if that is a problem.  As long as the delay 
is greater than 2 us it should still be guaranteed to work.  The 
encoders are only updated once per us as part of the digital 
filtering.

Jon

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