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Author Topic: Lost steps - again?  (Read 6000 times)

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Offline Hood

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Re: Lost steps - again?
« Reply #10 on: February 05, 2013, 10:40:09 AM »
Turn off the toolpath view and see if it helps, it could be that the large file is loading your computer too much. You turn it off from a button on Diagnostics page, its just above the Reset button.
Hood
Re: Lost steps - again?
« Reply #11 on: February 05, 2013, 01:05:03 PM »
Thank you!
I will try and see, but I think you are right...the problems started when I was tring to make a 32MB toolpath.
Never experience this issue before, however I will try to break the code in 3 or 4 smaller parts to avoid this issue

Offline mTron

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Re: Lost steps - again?
« Reply #12 on: February 08, 2013, 03:14:40 PM »
Hi Hood

The Dell Optiplex 755 has arrived in the meantime. I installed Mach3.043.022 and ran a few tests. At first sight all seemed to be well. Then I heard a thump from the steppers when I hit a key on the keyboard. I call it the sound of a missed step. It doesn't happen every time but often enough to worry about. And not all keys in all circumstances do it, but the space key to pause a running program is especially bad. When I hit it during a rapid move (G0) ever so often the screech and the lost steps are back!

After a through investigation I found that both the charge pump and the stepper pulses are cut out for some 400 microseconds every time I hit a key. The charge pump monostable is dimensioned at 290 us so it briefly disconnects the stepper drive which makes for the thump when it comes back. Making the monostable less stringent wouldn't resolve the problem because during those 400 us no stepper pulses are coming from the PC anyway. It seems that this is enough for the steppers (running at 20 kHz = 1200 mm/min @ 1000 pulses/mm) to lose track. My suspicion is that Dell has a concurrency problem between USB events (keyboard) and the LPT output. Scanning this forum for "Dell Optiplex" I seem not to be the first one having problems.

Apart of that the PC seems to be amply fast enough: The Windows (XP) task manager never showed more than 3% CPU load when running a reasonably complex G-code. And the PC is very small, just 26 x 9 x 26 cm and fits nicely under the workbench. What a shame!

So it seems there are a couple of options:
  • Buy another PC small enough for the workbench, e.g. one of the rare barebones with parallel port. But unless I can try that with Mach3 and the mill before actually buying it I risk another wasted expense.
  • Buy a SmoothStepper Ethernet. Electrically elegant, but not from a packaging point of view: There is not enough space left for it in the control electronic box - so I need another box plus power supply plus cabling.

What do you think?

Peter

Offline Hood

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Re: Lost steps - again?
« Reply #13 on: February 08, 2013, 05:03:50 PM »
I know Dells have a reputation for being bad with Mach, obviously not all but more than other brands I would say.

I think personally I would go ESS simply for the reason that you really should be able to run with any computer and any OS whether it be 32 or 64bit.
You could possibly fit the ESS inside the computer case and just run a parallel port cable to your control box.
That way you get the power from the computer.
Hood

Offline mTron

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Re: Lost steps - again?
« Reply #14 on: February 09, 2013, 05:34:10 AM »
You wrote "personally I would go ESS". Yes, this has become my favorite, too. Be it then, order an ESS at Warp9. I'll keep you posted how I get along, once I'll receive it. Thanks so far  :)
Peter

Offline Hood

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Re: Lost steps - again?
« Reply #15 on: February 09, 2013, 09:44:07 AM »
Well out of the options you had I would "personally go for" but on any new machines I am doing I am using the CS-Lab products as they are more suited to Industrial machines and wiring practices. Things like differential signalling and 24v I/O are much preferred for noise immunity.
Hood

Offline mTron

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Re: Lost steps - again?
« Reply #16 on: February 09, 2013, 11:30:33 AM »
Hm, just to avoid misunderstandings: My mill is nothing fancy (cf. attachment as a prototype with open gear), so I want to keep cost within reasonable limits. Less for cost reasons than for personal thrill I developed all of the control electrics and electronics in-house. So far I didn't experience much sorrow re. EMC and signal quality, but I know what you mean. therefore I shall have a look at CS-Lab. Thanks for the suggestion.
Peter

Offline mTron

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Re: Lost steps - again?
« Reply #17 on: February 09, 2013, 03:40:45 PM »
I had a brief look at CS-Lab's CSMIO IP-M. An impressive little box at a truly attractive price, indeed. If I started with a new CNC project this would be my favourite, too. But as things are my current system uses a slightly different approach: My hand control and the PC running Mach3 are connected to the stepper drivers via an electronic switch. If Mach3 is not running or the PC is off,I can control the mill directly using the hand control. That's how everything started. That's how I started machining the prototype drive gear. When I run Mach3, the hand control is ineffective and I use the jog functionality of Mach3.

Current CNC practice runs the hand control (MPG) through Mach3. In that context CSMIO IP-M exactly fills the bill. But I am glad that you directed my attention to CS-Labs. Whenever I should decide that my manual lathe might make good use of CNC...  ;)

Peter

Offline Hood

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Re: Lost steps - again?
« Reply #18 on: February 10, 2013, 04:18:04 AM »
The ESS is a great board, only thing is if wanting to integrate it into an industrial machine you need to do a lot of converting of signal voltages and you still need breakout boards, analogue I/O boards, Differential drivers and spindle control boards where the CSMIO boards all have that so its better for me.
If using 5v then as long as you are careful with correctly shielding the 5v signals all should be fine.
Hood

Offline mTron

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Re: Lost steps - again?
« Reply #19 on: March 02, 2013, 04:05:17 PM »
Another status report seems due: I bought an ESS from a local Swiss representative. Taking it into operation was a walk in the park. Everything seemed to work at first go. During my further tests I noticed a strange behaviour when holding the feed (Space-bar) while running a G-Code:
  • When I leave the control of feed-hold to Mach3 there is more than 2 seconds delay after hitting the space-bar until the feed actually stops. The same delay applies when I resume operation (<Alt>-R). This seems awful long to me, although the operation is precise, i.e. clean ramping down and no lost steps.
  • When I leave the control of feed-hold to ESS, the response is immediate with clean ramping down and no lost steps. However resuming operation behaves strangely: Motion starts immediately after <Alt>-R, but briefly pauses after about a second. If I pause and resume a second time within that 1 second time span, the feed (or rapid) motion briefly pauses twice. Again, no steps seem to get lost, but these pauses are not very confidence-inspiring to me.

Do you know these phenomena? Did I do something wrong e.g. in configuration? Are there any known workarounds? (Just as a reminder: I am using Mach3.043.022, because the most recent version did not want to restart after a feed hold...)

Thanks for your ideas