Re: EMC spindle speed control

garyswindell@... wrote

>Does EMC have the ability to control the spindle speed in some way?
>I notice there are bits on the parallel port definition for spindle
>speed decrease/increase, so I assume the answer is yes.

Gary

That's what assume gets you. <g> Spindle speed control is a neglected
area. What you see in the bridgeportio and ini were written to work with an
outboard device that cranked the speed on a bridgeport-like head. This
system did not have any real feedback and control of speed. What you hear
is what you get. There is some legacy C code from the initial K&T test
still laying around but folks think it is badly broken.

>Exactly how they are used and what they represent is what I am
>looking for.

forward, reverse, speed up, speed down, and brake defined on separate pins
of a parallel port. That is all they are. There is a bit of logic like
brake will turn off before spindle rotation and back on a settable time
after spindle off. A file named emc/src/emcio/tkio.tcl has some almost man
readable logic for spindle control. (lines 200 -> 500)

>I have an AC Tech variable speed drive. It can be controlled via RS-
>485. So I was planning on running the EMC control bits through a PIC
>so I could translate the EMC commands into the proper RS-485 commands
>for the VSD.

IMHO - The EMC spindle problem is a motion module problem. The g-code
interpreter reads spindle code like (M3 S3000) and issues canonical
commands to NML there is just nothing that I know of hanging around the NML
channel to comprehend or do anything with the S3000 part of the message at
the moment. (Don't even think about constant surface speed)

If you know the command set expected by your VSD through the RS-485 port a
few lines of code could be added to a program like tkio to read commanded
speed, open a serial port, and output the proper code to it.

Bi-directional commands could also be read from the serial port into tkio if
your device says something like, "3000 RPM. I'm there dude." It might be a
bit clunky but should work.

You might also ask on emc@....

HTH

Ray