The best computer for latency i came acros.

After testing and working with a looooot of different laptops and desktops, a friend gave me a Fujitsu Siemens Celsius workstation so i decided to do what i always do when i see or get a computer, start Linuxcnc and see how it does. Well, i am glad i did since i was amazed at how good and how stable it was (although Linux Mint does not start from the RAID 0 setup, Ubuntu 10.04 starts and runs without a hitch).
Take a look, i did do a 4 hour test while actually using it, it was the same result but i do not have a picture of it since i gave the workstation to my brother and he promptly installed windoze on it.......what a pity !!!

Oh it was a dual 4 core xeon with 16GB of RAM and 2X80GB hdd in a RAID 0 setup when i took that screenshot, running stock Ubuntu 10.04, linuxnc updated to 2.7, had a HD movie playing on media player, and a 1080p video on youtube, and 15 glxgears.

Nothing ???
I thought a computer that does consistently under 3000 ns latency would be the holy grail of LinuxCnc for software stepping, or did i miss something ?
More info.
I did run it for several hours with 15000 and 18000 ns in the ini file for base thread and i did get occasional error at 15000 when playing youtube hd video, but never at 18000 so i connected an encoder with 100 cpr directly to paraport and adjusted the speed of the servo motor with a voltage regulator and it did count without a hitch up to 7900 rpm for long periods of time (15 to 20 minutes at full speed) and never got any error. Theoretically it will count at 8330 rpm, but i had a limited voltage so i could not go further with that setup.
This practically means, with a 1000cpr encoder it can do 833 rpm, 500cpr will do 1666 rpm, 200cpr ( i have plenty of 200 cpr encoder attached to servo motors ranging from 50 to 200w) 4100 something rpm, while a 2000 cpr will go only to about 410 rpm.
I have to build some nice pwm drives before i get that computer back in september, and see how it does at running 4 or 5 axes at the same time. I am pretty sure it will do just fine, since i did have a similar setup with 4 axes a while back but on a computer with 100000 latency so i could use it at 750 rpm max with 200 cpr encoders.
time for bed, 2:36 am here.
tom

What is the brand and model of the motherboard in this PC?

No eBay APP ID and/or Cert ID defined in Kunena configurationNo eBay APP ID and/or Cert ID defined in Kunena configuration

Wirewrap wrote: What is the brand and model of the motherboard in this PC?

It is OEM fujitsu-siemens workstation, search eBay for Celsius workstations, must be plenty there.




Prices range from 130 to 300 euro for the silver older one, that is what tested. Mine had no paraport but an add-on PCI card with netmos chip.

As an extension of this topic.

I'm looking for a good LinuxCNC desktop candidate, but with powerful CPU. I need also to calculate toolpathes on it too with Blendercam.

Currently I'm using Intel Atom D425 (only 512Kb L2 cache, with 1.8Ghz frequency). Well, for step generation it's a good partner, but It horribly slow as a toolpath calculation machine.

Does anybody found fast CPU destktop for LinuxCNC?

It is best to start a new topic with a new and different question.

JT