LinuxCNC compatible industrial PC
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31 May 2025 23:04 #329476
by PCW
Replied by PCW on topic LinuxCNC compatible industrial PC
Note that for Mesa Ethernet cards the latency test is not terribly useful.
What is much more important is network latency. Default Mesa driver settings
will drop (timeout) packets if the return data takes more than 80% of the
servo period. As long as you do not drop packets due to these timeouts, latency is
relatively unimportant/
if you have a mesa card, try this:
sudo chrt 99 ping -i .001 -q -c 60000 10.10.10.10
(this will run for 1 minute and print delay statistics)
Change the IP address if you use 192.168.1.121
What is much more important is network latency. Default Mesa driver settings
will drop (timeout) packets if the return data takes more than 80% of the
servo period. As long as you do not drop packets due to these timeouts, latency is
relatively unimportant/
if you have a mesa card, try this:
sudo chrt 99 ping -i .001 -q -c 60000 10.10.10.10
(this will run for 1 minute and print delay statistics)
Change the IP address if you use 192.168.1.121
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02 Jun 2025 16:29 #329557
by workshop54
Replied by workshop54 on topic LinuxCNC compatible industrial PC
Thanks PCW,
I'll give that a try.
I'll give that a try.
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02 Jun 2025 17:42 #329559
by workshop54
Replied by workshop54 on topic LinuxCNC compatible industrial PC
Hi PCW,
Here are the results of the test you suggested. It is on a completely fresh install of LinuxCNC and I only changed the network settings using the standard ISO image. What do you think?
Here are the results of the test you suggested. It is on a completely fresh install of LinuxCNC and I only changed the network settings using the standard ISO image. What do you think?
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02 Jun 2025 18:20 #329561
by PCW
Replied by PCW on topic LinuxCNC compatible industrial PC
It looks like you have the host IP address set to 192.168.1.121.
This will not work, you need to set the host address to something
different but in the same network range, say 192.168.1.100
(in other words, you were not pinging the Mesa card but rather the host itself)
This will not work, you need to set the host address to something
different but in the same network range, say 192.168.1.100
(in other words, you were not pinging the Mesa card but rather the host itself)
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04 Jun 2025 08:20 #329673
by workshop54
Replied by workshop54 on topic LinuxCNC compatible industrial PC
I'm not sure what you mean PCW,
The ip address of the host is 192.168.1.100 as far as I can tell. (The Mesa card is connected to enp3s0)
The ip address of the host is 192.168.1.100 as far as I can tell. (The Mesa card is connected to enp3s0)
$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host noprefixroute
valid_lft forever preferred_lft forever
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
link/ether 00:01:c0:33:50:2a brd ff:ff:ff:ff:ff:ff
inet 192.168.1.165/24 brd 192.168.1.255 scope global dynamic noprefixroute enp2s0
valid_lft 86236sec preferred_lft 86236sec
inet6 fe80::62f5:a9e5:df33:68d6/64 scope link noprefixroute
valid_lft forever preferred_lft forever
3: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
link/ether 00:01:c0:33:50:2d brd ff:ff:ff:ff:ff:ff
inet 192.168.1.100/24 brd 192.168.1.255 scope global noprefixroute enp3s0
valid_lft forever preferred_lft forever
inet6 fe80::868a:991b:a25e:44d0/64 scope link noprefixroute
valid_lft forever preferred_lft forever
4: eno1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
link/ether 00:01:c0:3a:5b:8e brd ff:ff:ff:ff:ff:ff
altname enp0s29f1
5: eno2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
link/ether 00:01:c0:3a:5b:8f brd ff:ff:ff:ff:ff:ff
altname enp0s29f2$ sudo chrt 99 ping -i .001 -q -c 60000 192.168.1.121
PING 192.168.1.121 (192.168.1.121) 56(84) bytes of data.
--- 192.168.1.121 ping statistics ---
60000 packets transmitted, 60000 received, 0% packet loss, time 60002ms
rtt min/avg/max/mdev = 0.054/0.138/0.686/0.047 ms$ ip route get 192.168.1.121
192.168.1.121 dev enp3s0 src 192.168.1.100 uid 1000
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04 Jun 2025 10:22 #329681
by andypugh
Replied by andypugh on topic LinuxCNC compatible industrial PC
Late to the party, but I have recently switched both my machines to run from the Asrock N100DC-ITX board.
Latency is "fair" rather than good. But they are avaialble, run from 12V DC and can be booted from an M2 SSD for a neat installation in the machine cabinet.
www.mini-itx.com/~N100DC-ITX
(Unhelpfully, out of stock, maybe because I bought three of them from there.)
Apparently they are picky about memory, especially at 12V rather than 19V, so maybe buy memory at the same time.
Latency is "fair" rather than good. But they are avaialble, run from 12V DC and can be booted from an M2 SSD for a neat installation in the machine cabinet.
www.mini-itx.com/~N100DC-ITX
(Unhelpfully, out of stock, maybe because I bought three of them from there.)
Apparently they are picky about memory, especially at 12V rather than 19V, so maybe buy memory at the same time.
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04 Jun 2025 14:02 - 04 Jun 2025 14:04 #329688
by PCW
Replied by PCW on topic LinuxCNC compatible industrial PC
The N100DC draws no more than ~20 W...
Basically a laptop CPU in a Mini-ITX format
Basically a laptop CPU in a Mini-ITX format
Last edit: 04 Jun 2025 14:04 by PCW.
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04 Jun 2025 14:20 #329689
by PCW
Replied by PCW on topic LinuxCNC compatible industrial PC
I'm not sure what you mean PCW,
Your initial ping statistics had 3 and 4 usec times which are not
possible unless you are pinging the host.
Also the address range of enp3s0 overlaps enp2s0
This is why it's suggested to use the FPGA cards 10.10.10.10 address.
( as it will not overlap a local network DHCP range )
Your initial ping statistics had 3 and 4 usec times which are not
possible unless you are pinging the host.
Also the address range of enp3s0 overlaps enp2s0
This is why it's suggested to use the FPGA cards 10.10.10.10 address.
( as it will not overlap a local network DHCP range )
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04 Jun 2025 15:49 #329695
by workshop54
Replied by workshop54 on topic LinuxCNC compatible industrial PC
I tried to get the Mesa card on 10.10.10.10, but I never got that to work. I tried mesaflash --device 7i94t --addr 192.168.1.121 --set ip=10.10.10.10 before, but that didn't seem to change the boards IP address.
I ran the test again an now the values are probably more realistic:
What do you think about these values, and if they are good, are there any other tests you can recommend for this PC before I go all-in?
I ran the test again an now the values are probably more realistic:
$ sudo chrt 99 ping -i .001 -q -c 60000 192.168.1.121
PING 192.168.1.121 (192.168.1.121) 56(84) bytes of data.
--- 192.168.1.121 ping statistics ---
60000 packets transmitted, 60000 received, 0% packet loss, time 59999ms
rtt min/avg/max/mdev = 0.054/0.140/0.494/0.027 msWhat do you think about these values, and if they are good, are there any other tests you can recommend for this PC before I go all-in?
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04 Jun 2025 15:49 #329696
by PCW
Replied by PCW on topic LinuxCNC compatible industrial PC
Perhaps his ethernet is just really, really speedy.
Not physically possible with a 100BT link
100 Mbits/sec is 12.5 bytes/usec = ~5 usec for a minimum size packet
since packets need to be sent and echoed that's ~10 usec absolute
minimum for the smallest (64 byte) packet (ignoring overhead and response time)
Not physically possible with a 100BT link
100 Mbits/sec is 12.5 bytes/usec = ~5 usec for a minimum size packet
since packets need to be sent and echoed that's ~10 usec absolute
minimum for the smallest (64 byte) packet (ignoring overhead and response time)
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