The best computer for latency i came acros.

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08 May 2016 23:37 - 08 May 2016 23:47 #74385 by tommylight
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.
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Last edit: 08 May 2016 23:47 by tommylight. Reason: added more info

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16 May 2016 00:36 #74710 by tommylight
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

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16 May 2016 07:46 #74726 by Wirewrap
What is the brand and model of the motherboard in this PC?

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16 May 2016 15:57 - 16 May 2016 16:01 #74747 by tommylight

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.
m.ebay.de/itm/Fujitsu-Siemens-Celsius-R6...862845649?nav=SEARCH

m.ebay.de/itm/Fujitsu-Siemens-Celsius-In...987401517?nav=SEARCH

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.
Last edit: 16 May 2016 16:01 by tommylight. Reason: removed a link.

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02 Jun 2016 20:45 #75361 by tarasko
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?

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02 Jun 2016 21:20 #75363 by BigJohnT
It is best to start a new topic with a new and different question.

JT

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