2016-07-13 17:42 GMT-03:00 Peter C. Wallace <[email protected]>:

> The index pulse of a high resolution encoder is very likely to be too short
> for LinuxCNC to sense without hardware help.
>
> Imagine a 1000 count encoder with a index pulse that lasts one 1/2 cycle
> (same
> slot width as encoder) The index pulse width would be less than 1 ms at any
> speed over 30 RPM so likely to be missed at a 1 mS servo thread sample
> interval of HALScope. That is it might occur between HALScope sample
> intervals
>
>
> Index hardware in an encoder counter latches or clears the encoder count on
> index and typically sets a flag to tell LinuxCNC that an index event has
> occured. Because of this, a LinuxCNC system with a hardware encoder counter
> will not miss the index even even though the counter is only polled at 1 mS
> intervals
>

Thanks Peter for clarifying this. I thought halscope could be capable of
reading the index pulse even if I turn the motor really slow.

I suspect that the Index is working at least in one of my encoders
installed because it seems to find the home position when I ask for it (I
was using the direct homing option with this machine so I never intended to
use the index pulse).


-- 
*Leonardo Marsaglia*.
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