Dell Dimension 9200 jitter issue

Hi Everyone,

I recently bought a small 3 axes cnc machine that I would like to use for PCB milling.
As controller I´m trying to use a Dell Dimension 9200, but I´m getting a really long jitter times (330000ns )
This computer is a Pentium 4 with 1Gb of RAM and with
I´ve tried to disable hyperthreading and even the on-board audio chipset.
Due to its chipset, I thought it could be SMI related, so I changed the linuxcnc configuration to use the rtai_smi in order to disable the SMI.
Unfortunately none of these measure have made any difference.
If I try to use it I can move the axes but it seems rather slow. Additionally, as soon I click the "On" button, I get a strange "hisss" noise from the Z axes motor even if it´s not spinning.
Anything else I could try, or should I just forget it and look for another model?

I´m attaching a file with the output of lspci -vv.

Thanks in advance for your suggestions


, best regards:

Eric

Have you tried both 8.04 and 10.04?
8.04 often works better on older hardware.
If 8.04 works better you can update linuxcnc.

Rick G

Hi

You definately should be using 8.04 as Rick says
Install that first before trying anything else

Take some time to read these FAQs

www.linuxcnc.org/index.php/english/forum...-the-latency-problem

www.linuxcnc.org/index.php/english/forum...me-latency-solutions

Your chipset (ICH7 Rev6) is NOT one affected by the SMI problem, but that does not mean you cannot have similar spikes from
temperature sensing fan control etc, as per the second post on the latter FAQ

The main thing to do is work out where the spikes are coming from using the per second realtime latency test as detailed

regards

Additionally, as soon I click the "On" button, I get a strange "hisss" noise from the Z axes motor even if it´s not spinning.

Some stepper driver chips are quite 'noisy', I had a similar problem once.
It was worst if high micro-stepping was used, you could jog the axis slightly and it would quieten when it was holding on a real position and get noisy again
if you nudged it on to an interpolated position

That is one possibility.

regards

Dear Rick and ArcEye,

Thank you very much for your suggestions and the links to the relevant FAQs.
I will try an 8.04 installation and see how it goes.
By the way, I forgot to mention I also tried the proprietary and "open" NVIDIA drivers without any good result either.
The card is a NVIDIA GEFORCE 6800 with 256MB.
On this subject I´ve found some contradictory opinions too.
In one place I´ve read to stay away from the NVIDIA drivers, and on another one the recomendation is to replace the Ubuntu drivers with the one from NVIDIA well in any case I will stick with whatever works

I will let you know the outcome and if it work I will add the configuration to the hardware database.

Bye for now, regards:

Eric

In one place I´ve read to stay away from the NVIDIA drivers, and on another one the recomendation is to replace the Ubuntu drivers with the one from NVIDIA well in any case I will stick with whatever works

I doubt if you have read anywhere on this site to use the nvidia drivers
Their implementation of GL is normally problematic, they have no interest in latency, just gaming.

Use the open-source drivers, nouveau probably, but could be nv on 8.04
After or during the install you will be asked if you want to use 'non-free' drivers and software
Just say No and you should get the open source ones installed.

regards

Thanks again; 8.04 dowloading right now...
Hopefully I should be able to have a "verdict" some time today...

Regards:

Eric

Well, I thought this was going to be a bit easier ...

I got the 8.04 version, but when I tried it seems to detect the NVIDIA card put it gets configured with some weird values, and my TFT monitor is unable to display the image, it comes with an error message.
Sooo, I started in "graphic safe mode", basically 800x600 and I was able to run some latency test with far better results, between 7000 and 11500 maximum , so thank you for the advice!

Now comes the sad nightmare part, I´ve been trying all day to change the configuration to get a decent a resolution, at least enough to be able to see the complete page of stepconf and have access to all the options and buttons.
Unfortunately I've bumped into problem after problem. Only the vesa driver seems to work but with a maximum resolution of 800x600
The dexconf terminates with a weird bug "Battery module not installed"...
The jockey-gtk doesn´t work either, proprietary drivers are not available (it´s not my prefered path either)...
Envy is apparently no longer supported/available...
And so on ...

The sad thing is that under 10.04 the card and the monitor work perfectly

I had enough for today, but suggestions/solutions are most welcome as I start to be really desperate and running out of ideas

Regards:

Eric

Have you looked here...

wiki.linuxcnc.org/cgi-bin/wiki.pl?Troubl...oting#Display_Issues

Rick G

Probably time to find out how much the video card contributed to the original figures

Install whatever proprietary nvidia drivers are appropriate for the card under 8.04
(just open synaptic and search nvidia and start from there, you should be able to access the non-free, if not enable them in the sources menu)

regards