> >> On 01/26/2020 08:04 PM, John Dammeyer wrote:
> >>> I set my BBB aside when the Xylotex cape I had forced normally open
> limit
> >> switches.
> >> The limit switch polarity can be set in software.  In the
> >> configs file directory, in file
> >> CRAMPS.hal there is this :
> > Unfortunately not.  The signal was wired in hardware so the enable on the
> level translation devices was shut off when the switch was closed to ground.
> So a NO switch would close signalling not only a limit condition but also
> shutting off all the drivers.
> >
> > A NC switch would never allow step pulses out.
> >.
> Well, clearly this is a design defect in the breakout board,
> NOT a problem with LinuxCNC/Machinekit.
> Also makes homing kind of funny.
> 
> 
> Jon
> 
Which is why I went to BC Asset Recovery (Provincial Government Surplus) and 
bought two PCs for $75 each.  At that point it wasn't worth mucking around.  
And to be fair, although Xylotex wondered why I cared about NC or NO switches, 
the cape I have was discontinued and they now have one that is strictly I/O and 
probably way more suitable for MachineKit.  Available for $25 however their 
online ordering only supports US sales and I suspect shipping will cost more 
than the board.  Too bad it's not available through Amazon Prime.  Then I'd get 
it in a couple of days with free shipping.  Ah well...

http://xylotex.netfirms.com/OSCommerce/catalog/index.php?cPath=33&osCsid=399f6b4f8d069f3ae3d3569d71d7839c

And note, although it's still in the works, they are working on an FPGA board 
with 72 I/O

John Dammeyer



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