Laptop with low latency for use with Mesa Ethernet boards

Will edit this later and add link to a video, tablet is not behaving!
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Here is the link to the video, notice the Nvidia driver manager in the task bar, they are disabled for the test as it will mess up the latency a bit.


This is a test for an
Acer Aspire 5742 series
model no.PEW71 runing
Linuxcnc 2.9 on Linux mint 19.1 with 4.16.12-rt5-kona-rt kernel,
Mesa 7i92 attached through a cheap gigabit switch, servo thread is at 1ms and there are no latency issues.
It's been ruining for nearly a week wired directly to Mesa 7i92, no errors, even at heavy use of youtube and file copy. Intel core i5 M480 processor. BIOS is poor so not much to disable. Warning ! This is a proof of viability, not to be used on machines wired through switch, never. Direct connection of Mesa 7i92 ( or 7i96 or 7i76E or 7i80 ) to the PC Ethernet port is obligatory. Also as information on a good laptop with very low latency that is also very cheap. Not easy to find them........ this one was brought to me, gave 65 euro for it, although it is in pitiful condition visually.
FYI, the above mentioned Linux kernel can be found and downloaded in the debian packages site and it has much better latency than the ones i compiled following the tutorials on this forum, on some computers, not all. On some new computers it has no big difference in latency.

You should also do a small test so others can have info on what actually works with Mesa ethernet cards.

Gave it a heavy gcode file, set the maximum velocity to 19mm/m and left it for 4 days, it is still running and has another day and a half to go to the finish. Still no errors, no matter what i throw at it.
Not very useful info as they are hard to find.

1. I am curious, does the use of the mesa card mean that latency becomes less of an issue? If so what are the acceptable jitter limits using this setup?

Yes it does, that particular laptop has a latency of 100 to 120K, and it never fails, even after several days of constantly on and me using it online. I have some other laptops with latency of 200 to 300K and they get disconnected after 5 to 30 minutes of use as the tend to have excursions of over 2M !

ross_dev wrote:

I note from the standard installation procedure that usually you create the debian wheezy iso and install that way. You mentioned using mint here, is this using a dev build or is there an alternate way of installing LCNC into other OS?

No need to create anything, it is ready made, it needs just to be written to a USB and booted from it. Same goes for the Stretch version, this is the version to use with Mesa ethernet boards.
I use Mint and just install a precompiled kernel and Linuxcnc.

ross_dev wrote:

Also please could you expand on this line a little:

Warning ! This is a proof of viability, not to be used on machines wired through switch, never.

What do you mean by a switch, and why is it a particular issue?

Swith or router or hub, are equipment to connect several computer on the network.
Mesa ethernet cards should never be connected through any of the above, they should be ALWYS connected directly to the control PC.

Download the stretch version, write it to a USB, boot the laptop with it and run latency test while doing other things on it, like watch youtube and change to full screen several times, copy some big files from internal HDD to internal HDD and to USB, run glxgears from a terminal and also maximise and minimise several times, leave it on for a day or two, then check the latency.
Anything under 100 to 150K should be usable, but the only real test is to attach the mesa board to it and check if it looses the connection, while using the laptop for other things mentioned above.

That might still be usable, no way of knowing for sure untill you actually connect a Mesa board.