Re: Newby question about Home switches pin assignment

["Pete Cook" <kf2qd-at-terraworld.net>]

Actually the the limit switches depend more on the behavior of the drives
than the motion controller - Some servo drives have 2 inputs for limit
switches - one for each direction - means the machine can run onto it's
limit and then stop moving in thatdirection - jog the other way and drive
off it. Some servo drives have no limit switch inputs so the control has to
do all the limit switch logic. EIther way it is nice for the control to know
when a limit has been reached so some procedure can be folowed to handle
that condition - Retract the Z axis and stop, cntinue on and mess up the
workpiece, halt in position, or whatever.

Homing switches are nice if you have an input for each - all axis could be
homed at the same time - but with only one input you can homr one axis at a
time - as long as no axis is on a home switch at the time - then there must
be some logic to jog all axis away from the home switches untl the switches
are all in the correct state and then home all axis. During normal operation
the homing switches are meaningless - you just ignore them.

>
> That is very strange, why would EMC be coded in this way ? most driver
board
> will use separate home switch and a common limit switch. I hope that
future
> version of EMC will allow you to just specify these parameters in EMC.ini
>
> thanks for you help
> ----- Original Message -----
> From: "Paul" <paul.corner-at-tesco.net>
> To: "Multiple recipients of list" <emc-at-nist.gov>
> Sent: Friday, January 25, 2002 4:15 PM
> Subject: Re: Newby question about Home switches pin assignment
>
>
> >
> >
> > Hi Hugues
> >
> > Yes, But....
> >
> >  These changes will require some hacking to one of the ext***mot.c
sources
> > depending on which motion controller you are using. The limit switches
are
> > all read in by :-
> > steppermod and freqmod use extsmmot.c
> > smdromot uses extsmdromot.c
> > stgmot uses extstgmot.c
> > All of these can be found in src/emcmot.
> >
> > The step/direction pins are a little more involved, as these are hard
> coded
> > in emcmot.c and emcstepmot.c. Search for smController() and freqfunc()
to
> see
> > how it is done.
> >
> > Regards, Paul.
> >
> >
> > On Friday 25 January 2002 3:29 pm, Hugues Belanger wrote:
> > > Can anybody tell me if the home switch pin assignment can be modified
> > > emc.ini to match with my homemade controller.
> > >
> > > pin 10 --> Limit switches
> > > pin 11 --> X home
> > > pin 12 --> Y home
> > > pin 13 --> Z home
> > >
> > > Thanks in advance
> > > Hugues
> >
>
>
>