Help with com errors <Resolved>

[fusion]

I thought I had a stable system for my lathe. I ran the bench test including the stress test and everything seemed to work. Last night I was working on removing the X axis motor and I started getting COM errors.

I have attached 2 reports. One from 5/2/2025 and one from 5/20/2025.

The resend errors started on 5/3/2025 and disappeared for a few days and then came back hard on 5/18/2025.

The control cabinet is messy. I am not skilled in electronics.

I have no other relays than what comes with the Acorn board, and they are only used to control the VFD.
The VFD is located in the base cabinet of the lathe.
The 110v power enters on the lower left in the picture on the orange cable.
The power supply is from Antec and the stepper drivers are from StepperOnLine.com.
When I was working on the X motor mount last night, I noticed the hard drive LED blinking, and I wonder if Windows installed something that is causing this.
Thanks for any help you can provide.
Mike

[CentroidFrog]

1. Have you tried running our PC Tuner on the CNCPC?
Download here: https://www.centroidcnc.com/centroid_di ... loads.html
2. Have you gone through TB270?
https://www.centroidcnc.com/dealersuppo ... ds/270.pdf
3. Here's a post with videos and extra info on solving comm issues:
viewtopic.php?t=1451
4. In my attached image, it looks like this is a single wire being grounded in a seemingly random spot on the cabinet?
Best practice is to use a single grounding bus bar somewhere in the cabinet where all grounds can connect to.
Having several grounding points can cause ground loops and add extra noise into the system.
Cabinet best practices such as these are covered in the acorn install manual:
https://www.centroidcnc.com/centroid_di ... df#page=38

[fusion]

Thanks centroidFrog. I did run the PC tuner before the CNC software installation and after I received the com error messages.
I did go through TB270. This control is so simple the only item that seemed to apply was not running your ethernet cord close to a power line. There is about a 4" gap between the power line and the ethernet cable. I can try moving it to enter from the bottom right side. That would move it to about 10" away.
Do I need to ground the Acorn board to the chassis? I'll check that round location again. This may be a slightly old picture. I thought I had more than one wire connected there.
I have the Acorn board ground going to the 24V supply ground just as it came to me. Should that be taken off the 24V supply and applied to the lug in your picture? Also, the large Antec power supply didn't have a grounding location that I could find. Do I need one there? Also, is there a way to or do I need to ground the stepper drives? I didn't see anything like that on them.

I'm also going to see if windows has a restore point for me before the 5/3/25 date.
Thanks again.
Mike

[richardb15]

A bit tricky to see in the pictures, but it looks like your earths are interconnected using those twisty-on yellow things, that is a recipe for bad connections. Get rid of those and earth everything to one single brass bolt that itself it bolted to the main metal back panel. Also I can't see any screens on your motor/drive cables? Or of they are screened cables I can't see one end terminated at a ground point? Also looks like your mains feed to the top right power supply crosses and might be touching least two of the drive signal wires. Run all those motor and drive signal wires down the right and bottom edges of the cabinet, run all the mains power along the top, then you can run the DC low voltages down the middle. Just get everything seperated.

[richardb15]

It also looks like your ethernet cable is going through a clamp setup on the bottom left the cabinet. Might be daft, but make sure if it is that those clamp bolts are not too tight. I've seen before where those cables get interference if clamped too tight, even tight cable ties can cause comms issues on some systems.

[Ken Rychlik]

Agree. Get a new shielded ethernet cable and do not run it through the box with a clamp. Why is your ethernet cable wrapped in black tape? They make a rubber grommet you can push it through and not compromise the cable.

Fix all Ground issues to a single point from every source

[fusion]

Well in spite of my horrible craftsmanship, the Acorn is now humming along. It was a bad Ethernet cable. I probably damaged it with the clamp as suggested.
Installed a new cable and it works great.
Thanks for the help.
Mike

[fusion]

Well I’m seeing com errors again. I replaced the cable with another shielded Ethernet cable and it seemed to work fine.
I have discovered that when I get a com error, I can open the cabinet and wiggle the cable a little and the com errors go away. It’s like the Ethernet receptacle on the Acorn board is loose. I removed the plexiglass cover from the acorn and pushed gently on the little board holding the Ethernet port. A made sure there was no stress on the plug while in the port and zip tied the cable to prevent movement.
Right now it’s working perfectly.
I will order a new cable if this continues.
Has anyone else seen the Ethernet port causing com issues?
Thanks!
Mike

[fusion]

It was working fine. Came back 3 hours later and I’m getting com errors again.

[fusion]

I installed a new shielded cable. This time only 3' long. It seemed to work fine, as it passed the stress test repeatedly. I went back to it a few hours later and it was failing the stress test. Nothing had changed.

I noticed though that the order I started the PC vs the control had an impact. If I started the control before the PC was completely booted, I would get a failure on the stress test. If I waited until the PC was booted and stable, then started the control, it would pass the stress test. I'll keep monitoring it. If anything changes, I'll update this post.