Prob running but not jogging

[MechanoMan]

big long thread, the whole sad story http://www.cnczone.com/forums/showth...t=69746&page=4

But don't bother reading that. What I've got is a 741GX-M2 motherboard with on-board parallel port. It had onboard video but I installed an external card. It's an AMD processor, 2.6GHz IIRC, a meg or two of ram. It's on a Taig "DeepGroove1" with 280oz steppers, someone said they were Xylotex but I'm starting to doubt that since it doesn't say that on the boards just "deepgroove1".

After enough dicking around with it I made up a separate install of Windows XP in Standard PC not ACPI mode and no firewall, antivirus, etc. Just that and the drivers. DriverTest declared my system "Excellent", just like it did under my old OS installation. The problem below is still there.

Well, it's pretty bad about stalling out. I ended up having to take it down to a maddenling slow 10ipm. However, here's the thing- I can JOG at 30ipm through the keyboard without trouble. I've got jog rate set to 100% full speed and it reports 745mm/min with either keyboard jogging or Mach3 driving it. But let Mach3 do the driving- for example set zero at the table, run the z-axis up then tell it to "Goto Z" so it goes down to it- the motor WILL stall in 5 sec like clockwork. Monkeying with pulse width, Sherline 1/2 Pulse Mode, etc doesn't seem to have any effect. No matter what position the Z starts in. I've noted this on the other axis too- running code causes failures even though jogging does not.

WTF? Anybody wanna clarify? Why is the run different when Mach3 generates the moves? What I'm getting from this is it's not the motors nor the driver. It's gotta be in the computer hardware (or Mach3).

I have an oscilloscope. I'm looking at the waveforms here on the Step pulse. 0v to 4V peak, but not 5V. What I'm seeing is MOST pulses are 67.5usec apart, but some are 45usec. I'm seeing a flicker of a pulse right there. And it's not wandering around, it shows up right at that point without a lot of jitter. Changing freq doesn't do anything to the look of the waveform. Changing motor speed does, that causes the odd pulse at 22.5 earlier than the majority of pulses- which is the same as observed before- but the majority of pulses are further apart in accordance with the speed..

Is that "normal", some sort of undocumented Mach3 anti-resonance feature, or am I straight out looking at one of the dreaded this-parallel-port-won't-cut-it things?

[MechanoMan]

Huh just tried my HP ze4400 laptop (like 6 yrs old) and that thing does NOT stall the motor right at 5 sec like that at the same speed. Also checked it on the scope and it shows the same 22.5us-early pulses feature. I'm not sure what that tells me.

[neilw20]

If you are using USB mouser and or keyboard, try conventional PS2.
I got rid of USB keyboard. It was chewing up CPU cycles.
I end up ditching XP and use Win2000. Now NO PROBLEMS.
Something is using CPU cycles.
Is this problem evident using MDI using G1, or is only with a program?
What have you set KHz to in Mach3? 25KHz or is it higher?

[MechanoMan]

Well it's not in front of me right now but based on what I've seen, G1 moves do stall it, and I've no doubt at all MDI will too.