When running a job with CNC12, occasionally two red lines of text will appear noting “452 Ethernet Communication Error, see Tech Bulletin 270”
If there is an ethernet connection loss of signal with the laptop, the job continues to run, unlike Mach4. That’s a good thing. The laptop does connect (pausing/ tool check still work), so I’m not sure what the ethernet loss is or what CNC12 is warning me about.
What is causing this? Is there a Tech Bulletin that users can review?
Thanks
Scroll down to number 270 on Centroid’s Tech Bulletin page:
https://www.centroidcnc.com/centroid_diy/tech_bulletins/browse.php
You’ll see TB#270 there to download.
Direct link: https://www.centroidcnc.com/dealersupport/tech_bulletins/uploads/270.pdf
Can you describe your setup a little?
Are you using our ethernet cable we supplied? Is that cable near any other cabling? (like your spindle cable and such)
What kind of PC are you running?
I am getting this same issue with almost every job. My hypothesis is that it might be because my dust collector is plugged into the same circuit and surge protector. I thought I had seen a thread on here last week, but I cant find it anymore 
I am using the supplied shielded ethernet cable. I was going to try a different circuit for the dust collection, and a double shielded cable, this weekend.
Maybe you have your computer on the same circuit as dust collection?
You can try to run a communications stress test:
You can run these as many times as you want, and you can try it with the dust collector on/off. It basically simulates a heavy load on your PC>Controller communications without having to actually run a job.
I will definitely try this this weekend!
Make sure your computer is turned on completey before you power on the control box with the Acorn in it.
I know both Centroid and AVID say this isn’t a requirement, but I have had issues on all 3 of the Acorns I’ve tried, and 4 different computers, and a couple others have tried this as well and got the same results. Sometimes I don’t get any connection at all (i.e. CNC12 won’t even start up because it can’t connect to Acorn), but sometimes it will start and be fine until i run a job. However, it will ALWAYS fail the above mentioned communication test if I don’t have the PC running first.
I like the dust collector theory. Mine randomly starts my dishwasher.
If mine did that I would take credit for it with my wife.
It won’t be due to my dust collector. It’s on its own 240V/ 1-phase circuit. The Avid spindle is on its own 240V/ 3-phase circuit. The Avid EX control box and my laptop are plugged into the same 120V/ 1-phase duplex outlet.
I haven’t tried Eric’s comm stress test yet.
FWIW, the problem isn’t isolation of the circuits, but rather grounding, and static electricity caused by the dust going through the tubing/hoses. So, it could still be the dust collector.
'lectrcity’s funny like that
I’m experiencing this same issue now. Processing a sheet with cabinet parts, everything was working well and was getting to the end of the tool path at the front right corner and machine stopped. I performed the stress test several times and PASSED the test. I then tested it again with dust collector running, PASSED again. Grounded dust collector at the machine, also where the flex transitions to hard metal pipe and at the dust collector itself. Ran the test and PASSED again. PC and controller are on a dedicated circuit, dust is on a dedicated too. I re-ran the job and it was working fine, I mentioned location because oddly enough the machine stopped 1.5" beyond the last spot it stopped! Any ideas would be very helpful! Show must go on.
Thanks J
Talk to me about your setup…
Where does your ethernet cable go, and which cable are you using? (the one we provided or another one)
What message are you seeing on screen when the stoppage occurs?
Did you optimize your PC with the PC Tuner?
Thank you, Eric,
We are using the cable that came with the machine. Our laptop did not have an ethernet port so we bought an adapter (J5 Create USB 3.0 gigabit ethernet)
The message is:
452 ethernet communication error
CNCPC to controller
We think we first set up our machine we did optimize with the PC tuner
Thanks,
J
You might want to swap that ethernet adapter for another one… I’ve never heard of “J5 Create”
I have had great luck with these:
They’re cheap, made by a known brand and have never failed me.
I’d try that first. Sounds like you did a decent amount of other testing with the stress tests.
If that doesn’t solve it open up a support ticket with us and we can dig deeper.
Centroid in their tech bulletin 270, related to this problem, specifically says don’t use a USB ethernet adapter. We are seeing these errors after a CRP to EX upgrade … feeling like we’ve traded one mess for another.
That tech bulletin, while good was back from a time when USB>Ethernet adapters were not great. The reality is that on many modern computers it’s the only way to connect.
We have LOTS of them out in the field that are working fine. Ethernet communication issues are pretty rare as well.
Here are some things you can do to diagnose:
-MAKE SURE you’re using a shielded ethernet cable. We sent you one with your controller. If you’re using any other cable swap it out for ours.
-Make sure that your ethernet connections aren’t dirty, and that they’re not next to a high power cable (like your spindle cable)
-Run the PC tuner again to make sure that your PC is configured correctly
Also, every now and then we find an ethernet adapter that just doesn’t play nice with a PC. If you have another ethernet adapter I’d recommend trying that (perhaps your PC has a built in ethernet port)
Also, if you want to test connectivity you can load a job in CNCM\SYSTEM called “com_stress_test”
This file will simulate a heavy communication load between your PC and the control, this can be great for testing different adapters, cables and cable routing
If these steps don’t solve it open up a ticket using the contact button above
I have an issue with this.
The machine says go look at the bulletin …
The bulletin , last updated 1/2/2026, says using USB/ethernet is a mistake … is it?
If its wrong please update it to say use a quality USB, or use this USB … Centroid isn’t shy about specing SSD brands so why not here too. Weve abandoned USB ethernet ans switched to a PC
with a dedicated port.
We are using the cable AVID supplied.
Our connections aren’t dirty … ports have been blown out and inspected cable ends inspected and wiped. (PC ethernet port / EX controller ethernet port)
I’m assuming that AVID ran the Centroid CNC controller bench test … or should we do that?
While the stress test can confirm correct operation, we already know we have a comm problem .. so what value will the stress test provide?
Seems like the community points at grounding as a potential contributing factor … so … we will apply mechanical grounds between the PC and the machine, the monitor and the machine, the machine and our metal duct collection ducting.
This is frustrating
