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Offline Davek0974

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Kernel speed change
« on: December 31, 2015, 01:05:58 PM »
Hi all


does changing the Kernel speed upset or affect any other settings???

I have to replace the pc on my plasma table tomorrow and was wondering if it was also a good time to reduce kernel speed as I am fairly certain its too high.

Currently on 35khz was thinking of dropping to 25khz.

Won't bother if it upsets anything else as i really don't want to retune everything.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline beefy

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Re: Kernel speed change
« Reply #1 on: December 31, 2015, 04:29:14 PM »
Dave,

this is what I heard about kernel speed. I always thought faster was better then I got told use the minimum kernel speed that is fast enough to run your motors.

I used to have mine set at least 45,000 then reduced it to 25,000. Sometimes it was OK but other times, Mach3 would give me a message saying my kernel  speed is too low, so I settled on 35,000

A faster kernel speed is supposed to put extra load on the computer whether the motors are running or not, so the theory was the lower your kernel speed the better the system stability.

As far as I am aware, changing the kernel speed does not affect anything, it simply allows faster tighter timing (if it's needed). Maybe someone with more knowledge than me can add to this.

Keith.
Re: Kernel speed change
« Reply #2 on: December 31, 2015, 07:02:00 PM »
Hi,

When you change the kernel speed you will need to retune the velocity and acceleration of each axis. You may just need to go into the tuning table and resave the settings for each axis.

Also if you are using the debounce function you may need to increase the count if you increase the kernel speed as the debounce value is the number olof kernel ticks that the debounce lasts for.

Cheers,

Peter

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Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline Davek0974

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Re: Kernel speed change
« Reply #3 on: January 01, 2016, 03:53:55 AM »
Ok thanks

but the overall effect of steps per and acceleration / speed should remain the same no?
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Davek0974

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Re: Kernel speed change
« Reply #4 on: January 01, 2016, 01:41:09 PM »
Hmm, changed the PC and updated the the software to be exactly like the old PC that failed, did not change the Kernel speed yet, all appears OK to a point but not as stable now?

Mach went into reset in the middle of a test cut and also appeared to freeze while doing nothing once.

Will have another check tomorrow but not out out of the woods yet I think :(

It's a different make PC, last one was some generic junk clone and this is a Dell Optiplex with tons more power and ram etc not sure what else to check????
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline beefy

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Re: Kernel speed change
« Reply #5 on: January 01, 2016, 03:56:29 PM »
My experience has been the power of the PC is very often NOT related to the stability of Mach3. I've found the model of PC (motherboard) is more the determining factor.

The 500 series of Dells are known to be a death sentence for Mach3. I've heard the GX620 is great as are some of the 700 series. Overall, I seem to have had good success with a lot of Intel motherboards, and have got quite a few flat line driver tests at 100,000 kernel speed.

I always install XP in "standard PC mode", go through the XP optimisation, and disable ANY service I think is not needed in XP to run Mach3.

I once turned down a job because I got spooked by Mach3 (oh that's unusual). In the middle of a cut everything just stopped, no error messages, nothing. And it wasn not a command in the gcode either. All I can put it down to is something interrupted Mach3 and then Mach3 just downed tools. It's reasons like this I go overboard when installing XP and finding PCs that seem to "get on well" with Mach3.

Keith

Offline Davek0974

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Re: Kernel speed change
« Reply #6 on: January 01, 2016, 04:06:55 PM »
Hmm, this one is a GX620 and i have a GX520 in the cupboard as spare.

Will check it again tomorrow, today was a bit rushed as i had a job to cut and also had to rush out.

This one sort of went blind, I could jog it but not ref all or run any code, odd.

Reloaded Mach and got the job done ok.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: Kernel speed change
« Reply #7 on: January 01, 2016, 07:46:15 PM »
The steps/per is the same, but the velocity and acceleration will change. This is because they are stored in iterations of the kernel rate.
For instance, a velocity of 1 step every 1000 kernel iterations will be a different velocity when the kernel rate is 45KHz as compared to 25KHz.

Also the debounce  period will be a lot shorter if you increase the kernel speed. That possibly may be the reason for the estop durring a cutting operation.

Cheers,

Peter

Ok thanks

but the overall effect of steps per and acceleration / speed should remain the same no?
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http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline Davek0974

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Re: Kernel speed change
« Reply #8 on: January 02, 2016, 03:57:08 AM »
Thanks Peter, that makes sense now.

I have not changed the speed yet, wanted to verify the new pc was working before messing,  I am going to go through the settings today and run some more tests.

Hopefully it will settle down.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives