Re: TURBO CNC "hangs up"

Good morning Marcos:

Interesting issue; I can honestly say that runaway steppers are a
new one to me... Let's see if we can work this out.

I looked up the specs for your stepper drives. Should be fine to
drive from a parallel port - the note on their specsheet that says
1.2ms pulse width min must be a typo, as they rate it to 400Khz. So
that should be good to drive with the default pulsewidth of 0 and so on.

If you can jog the machine, that means you've probably got the step
and direction pinouts all squared away. Your instinct to look for
electrical noise is a good one - usually noise pickup on a step line
causes a pretty slow and irregular step, but if you have a PWM spindle
drive or something than a higher rate couldn't be ruled out. If the
issue persists with all "unusual" electrical stuff off, or moved
further away, then it's probably not that either.

Don't worry about the pin states - it's a distraction from the real
issue. On a parallel port it's normal for the pins to float up or
down with nothing connected, and on pins 1,14,16,17 you'll see a ghost
5V signal with a scope when it's supposedly in input mode; this has to
do with how the IO is implemented in the hardware.

When you wire up your limit switches you want a pullup resistor
(typically 2.2k) to 5V or a similar pulldown to ground on each pin to
force the state when the switch is not. In TurboCNC, you can hit F2
for the port monitor to pop up so you can see what the computer thinks
is happening on the port. Alternately, you can use FKEYBIT (in the
\utils directory) to do the same thing, and to manually toggle the
port lines on and off.

You've left out a crucial detail in your post though that prevents
me from actually figuring out the problem - if "everything seems to
work just fine...i can jog" , all that left is to ask what instigates
the runaway condition? I'm gathering that it's reproducible.

So did you ask it to home? Did you load/run a file? Hit the
printscreen key (yes, someone has done this before)? Is it seemingly
random?

I can think of two things:

- Stuck key on the keyboard?

- In jog mode, the acceleration rate determines how quickly the
steppers come to a stop. This is in steps/second gained or lost per
second, so 1000Hz/s accel for a 2000Hz step rate means that it takes 2
seconds to come to a stop from full speed. If you put a number like
10 in there, it'll take quite a while longer. It would take an
equally long time to reach full speed also.

You wrote that even the "emergency switch" doesn't work. In
general, ESC on the keyboard will get you out of trouble anywhere in
the program - a lot of folks use that as the e-stop. Is this what you
meant, or is the emergency switch a different part of your hardware?
Initially I thought the former, but re-reading your post I'm not sure
as you mentioned a "CNC BOX" as well.

Reply to the list or email me direct, no problem...

If you've made it this far building a machine you're almost there,
like 99%, so this shouldn't be a big deal to wrap up.

Dave Kowalczyk
Kent, WA
TurboCNC software --> http://www.dakeng.com/turbo.html

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Marcos Leandro gonzalez
Brughetti" <marcos_brughetti@...> wrote:

>
> Hi, im trying my "just finished" cnc lathe,wich i design and built
> from cero. i have controllers hooked up, (leadshine 5056) and
> everything seems to work just fine...i can jog, i can use the limit
> switches, etc, but the computer or just "turbo cnc" hangs up, and
> when it does, even the EMERGENCY SWITCH doesnt works. and the
> steppers keep on runing,
> so its a real problem. i have to quick shut off my "CNC BOX" to turn
> of my spindle and stop the steppers...and preventing them
> to "destroy" the lathe
>
> I boot to DOS directly. just for reference
>
> only thing "weird" is that i have my limit switches wired to pin 11,
> and 12, and those pins are high state and low state ,respectively.
> both in NORMAL STATE; WITH NOTHING HOOKED UP to it.
>
> i have them as wired as :
>
> pin 11 (home switch & limit for X), high state , configured as ACTIVE
> LOW
> pin 12, (home switch & limit for Z) low state , configured as ACTIVE
> HIGH
> what i did now was un-hook the spindle from the relay that is
> controlled via pin 14, so i eliminate that as a problem/interference
> and turn it on, and off using a regular switch. (its a low power
> command, that comes out of my siemens-micromaster 420) but is
> disconnected it anyway.. the problem persists.
>
> i cant try mach2 demo or anything else, because my cnc pc is a
> celeron 300mhz/64/6gb. so on this pc only resource should be TCNC.
>
> sorry if the post is writen confusing.
>
> i hope someone can help.thanks in advance
> MARCOS
>