Re: emc spindle

[Jon Elson <jmelson-at-artsci.wustl.edu>]

Fred Proctor wrote:

> The differences between minimilltask/io and bridgeporttask/io are in the
> handling of the spindle and estop. In the minimill controller, spindle
> commands are sent as DAC writes to the 4th axis of the servo to go. The
> estop sense is simulated as being equal to the estop output.
>
> Ming Him Mak reports that it doesn't work, which isn't surprising since
> the software probably rusted since the last time I tried this, about a
> year ago. I'll look into this, but in the meantime brave souls can try
> to figure this out. The way I'd do it is to run the Linux "emcmotsim"
> instead of the RT Linux stgmod.o, so that you can debug it, e.g.,

I spent an evening tracking through the code.  I found where the interpreter

sends the speed setting to the next level, but it seems to only send it to
an object called simSpindleSpeed, which sounds like it might be in a
simulation module, only.  I scanned all through minimillio.cc and
minimilltaksintf.cc, and found where all the other spindle commands were,
(forward, backward, brake on and off, etc.) but didn't find a single line
of code that actually accepted the spindle speed setting and did
something with it.

It also looks like there might be some .ini file parameters, like
VOLTS_PER_RPM
and EMCMOT_DAC_OUT that might need to be set at run time.

But, I think I can see why Ming Him Mak says it doesn't work.

Anyway, what I'd like, whenever someone gets time to poke at it,
would be to have the DAC channel selected in some configurable
manner, either a .ini file parameter, or by selecting the first unused
DAC channel (MAX_AXIS+1).  This should also be configurable
such that the DAC can give only positive values, and the spindle
direction is commanded with a forward and a reverse start line,
or that the DAC output would be bipolar, and there would only be
one spindle start line.  This would make a very flexible system
for controlling anything from a VFD on a mill spindle to a full
servo spindle on a turning center.

Thanks,

Jon