I just started to take a look at the code and have concluded that there is 
evil lurking there.

Right now, the code zips through the interpreter keeping track of the 
position, the modes, etc. Consider what happens with things like a change of 
direction. We are going clockwise and want to go counter clockwise. So we 
stop the clockwise motion. Then we pause (G1 P5) for five seconds so the 
motion has time to stop. Then we start the counter clockwise motion.

If we are not actually executing the code, the pause won't take effect.  I 
think that mean that we do NOT want to start the motion at the point in the 
code where the command occurs

----------

In my brief (ten minute) scan of the code, I thought I saw that all of the 
modal stuff is actually saved. So, the change should be that when we get to 
the spot in the code where we want to execute again, we should restore all 
of the hardware related modal stuff. I think that means we restore the 
proper tool, we set the proper gear and set the proper speed, we turn on 
motion in the proper direction, we turn the coolant on or off. And all of 
the other things like that.

Notice that I included changing gears. I don't know how people with machines 
requiring a change of gears are doing that, but if this is to work for them, 
they need to handle it with m-codes and "S" values that are timing 
independent at the interpreter level.

[Whoops. I just contradicted my initial section of this note. Anyone who 
uses a pause to safely change spindle direction is doing it the wrong way. 
The underlying system integration should do things like disallowing motion 
until the spindle is up to speed, and preventing damage from changes of 
spindle direction without a pause.]

Ken



Kenneth Lerman
Mark Kenny Products Company, LLC
55 Main Street
Newtown, CT 06470
888-ISO-SEVO
203-426-7166
----- Original Message ----- 
From: "Jon Elson" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Saturday, May 03, 2008 1:01 PM
Subject: Re: [Emc-developers] [Emc-commit] joints_axes emc2 TODO, 
1.27,1.27.8.1


> Alex Joni wrote:
>> Modified file emc2/TODO
>> +
>>  THINGS THAT ARE DESIRABLE FOR THE NEXT MAJOR RELEASE (EMC-2.3)
>>
>>  TODO     sort out axis/joints issues:
> Any comments on the problem with not starting the spindle when
> you start from the middle of a program?  I consider this to be a
> pretty glaring bug, but don't have any idea how hard it would be
> to fix.  Obviously many other modal settings are being handled
> as the program is scanned.  Is this too ambitious to put in the
> to-do list?
>
> Jon
>
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