Help selecting new PC to run Mesa 7I92 Ethernet

Hello community
I have a running punching machine on Linuxcnc, I used a dell old PC and it passed latency test with 35000 nano second.
It's connected to Mesa Ethernet Card 7I92 then 7I74, 7I77 and 3*7I84 to control two DC servo motors and the rest of the digital IO's.
The problem that It's impossible to tune the servo motors and I think it's due to PC hardware, I can't set SERVO_PERIOD below 1,000,000 otherwise I get the below message once starting Linuxcnc

Unexpected realtime delay on task 0
This Message will only display once per session.
Run the Latency Test and resolve before continuing.

I finally decided to replace the PC with a new one, I read in the forum that GIGABYTE BRIX with J1900 is good with Mesa Ethernet, I can buy it but with Celeron N2807
I need to know whether the GIGABYTE BRIX with Celeron N2807 will solve my problem or not?

this is a good choice
everything below 50000

the MESA got its own Clock so you do not need this BASEtread

only if you like to run special components
you will be fine with it
i use 7i92 alot

I would not give up on the Dell so quickly

Can you do a few checks?

1. Run the command:

lspci | grep -i ether

and post the results here

2. run the command

uname -a

and post the results here


Also 1 KHz should be fine for velocity mode drives.
Its the standard LinuxCNC servo rate.
Normally you only need to go faster if you have torque mode drives or a system
with very high acceleration+accuracy requirements (like a laser plotter)

pl7i92 wrote:

this is a good choice
everything below 50000

the MESA got its own Clock so you do not need this BASEtread

only if you like to run special components
you will be fine with it
i use 7i92 alot

Thanks gor your feedback

PCW wrote:

I would not give up on the Dell so quickly

Can you do a few checks?

1. Run the command:

lspci | grep -i ether

and post the results here

2. run the command

uname -a

and post the results here


Also 1 KHz should be fine for velocity mode drives.
Its the standard LinuxCNC servo rate.
Normally you only need to go faster if you have torque mode drives or a system
with very high acceleration+accuracy requirements (like a laser plotter)

Thanks PCW for your support
I don't know if it's high speed or not
The machine maximum speed 45 meters/minute, accuracy 0.01 mm
I'll check the commands and get back to you as soon as possible

This is the result of the two commands

PCW wrote:

1. Run the command:

lspci | grep -i ether

00:19.0 Ethernet controller: Intel Corporation 82579LM Gigabit Network Connection (rev 04)

PCW wrote:

2. run the command

uname -a

Linux Trumpf 3.2.0-4-rt-686-pae #1 SMP PREEMPT RT Debian 3.2.84-2 i686 GNU/Linux

The PC its HP not Dell
HP Compaq 8200 Elite SFF
Processor: Intel i5-2400 @ 3.10 GHz

tommylight wrote:

Those are very fast machines, they move the table at scary velocities.
Do you have any pictures of it or videos or configuration files? There was a user here a while back asking for help on retrofitting one, but no one helped him, not even a user who has a working machine on YouTube and asks here for help often, but does not help anyone, ever.
It would be nice if you could upload anything here to have as a showcase.
Thank you.
Now, what control and servo drives and motors does it use? Is it Fanuc Red Cap motors?
Also have a read through this, slowly and make sure you understand what you are doing, as I said above they do move very fast, here is the link:

forum.linuxcnc.org/10-advanced-configura...ning-detailed-how-to

It's my pleasure to share my work with you tommylight
I'll record a video and upload configuration file here soon
The DC Servo motors are ABB controlled by BOSCH Drives
I already followed your procedure to tune motors but I barely get the straight line and it change with the time, that's why I wanted to replace the PC

OK so you have a intel MAC, this means you will need to disable a Ethernet driver feature called "IRQ coalescing" if you have not already. This is described in hm2_eth man page

You can do this temporarily (till the next reboot) with the command:

sudo ethtool -C [your_ethernet_device_name] rx-usecs 0

Where [your_ethernet_device] is eth0,enp0s25 or similar
You can determine the Ethernet device with the command:
ip a

You can check if this works by checking the 7i92 ping times before and
after you run the above ethtool command

Can you post a halscope plot image of the problem you see?
From your description, it does not seem servo thread or PC timing related

you can also do this in the interfaces
sudo gedit /etc/network/interfaces

#7i92 2019
auto eth0
iface eth0 inet static
address 192.168.1.4
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1
dns-nameservers 8.8.8.8 4.4.4.4
hardware-irq-coalesce-rx-usecs 0


then
sudo /etc/init.d/networking restart
if it fails
sudo /etc/init.d/networking stop
sudo /etc/init.d/networking start

ofcause as you got the 7i92 jumperd
if yoiu use other networking adresses just correct it