GRBL Error: Cannot open port for Nomad

Assembly questions and answers for the Shapeoko 3 CNC Mill
andrewhoffman65
Posts: 1
Joined: Sat Apr 25, 2015 9:02 pm

GRBL Error: Cannot open port for Nomad

Post by andrewhoffman65 » Fri Jul 10, 2015 4:04 am

Since I first set up my shapeoko 3 I keep losing connection in the middle of cutting. Almost every time I try and use it I lose connection and get an error. GRBL Error: Cannot open port for Nomad.

I have tried the CNC on two different computers and tried using a new USB cable. I have also tried running it through a power conditioner. I am just wondering if anyone has any ideas of what could be wrong or if there is anything I could do. I have emailed support and they sent me the following and didn't really give me any suggestions.

We've had another customer with a similar problem and it seemed like it might be static electricity or an ESD problem. Based on the weather where you live.

WillAdams
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Location: Pennsylvania --- south of the Turnpike, East of US-15
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Re: GRBL Error: Cannot open port for Nomad

Post by WillAdams » Fri Jul 10, 2015 10:59 am

What they were trying to suggest w/ the mention of static electricity I believe, is that it might be resolved by grounding the two machines, and their connection.

The problem is, this has to be done in such a way as to not create ground loops.

While we have a bit on this on the wiki for the SO1 and 2, we haven’t had a formal examination of how to do this for the SO3. http://www.shapeoko.com/wiki/index.php/ ... #Grounding

If I understand correctly, electrically isolating the USB may help. One commercial product for this is: http://www.amazon.com/dp/B00F4SCCR2 HifimeDIY USB Isolator. ADUM4160 5000V signal isolation

Essentially what you want to do is create star topology from the ground to each discrete component of the machine which is electrically isolated. I believe that would be:

- spindle / Z-axis carriage
- x-axis carriage
- machine gantry / heat sink elements of the Carbide motion board
- machine frame
- power supply ground --- this is where all the grounding connections for the machine should be made

I believe that’s correct. Any correction, clarification or confirmation by someone who actually understands this stuff would be welcome.

What I’m hazy on is the electronics:

- Carbide Motion Board --- are the electronics separate from the heat sink portion of the board?
- USB --- does this ground at the computer end?
- control computer system --- what should be done to ground a computer system such as a laptop which uses a two prong connection?
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)

chipmaker
Posts: 15
Joined: Tue Jul 21, 2015 2:36 pm

Re: GRBL Error: Cannot open port for Nomad

Post by chipmaker » Wed Aug 05, 2015 9:33 pm

andrewhoffman65 wrote:Since I first set up my shapeoko 3 I keep losing connection in the middle of cutting. Almost every time I try and use it I lose connection and get an error. GRBL Error: Cannot open port for Nomad.

I have tried the CNC on two different computers and tried using a new USB cable. I have also tried running it through a power conditioner. I am just wondering if anyone has any ideas of what could be wrong or if there is anything I could do. I have emailed support and they sent me the following and didn't really give me any suggestions.

We've had another customer with a similar problem and it seemed like it might be static electricity or an ESD problem. Based on the weather where you live.

Hey, just wondering if you had any resolution to this problem? I have been chasing my tail with it, big time, and wondering if anyone has had a breakthrough. Unfortunately it is really costing a lot of time and frustration, and I need to get this machine up and running quickly. If you did figure this out, I'd love to know how... glad I read this first, I was about to go buy a line conditioner. Thanks!

houndel
Posts: 21
Joined: Fri Apr 24, 2015 11:38 pm

Re: GRBL Error: Cannot open port for Nomad

Post by houndel » Tue Oct 13, 2015 6:16 am

Hi,

Sadly I'm having the same issue: just as the spindle gets up to speed the connection drops out.

Also tried changing the USB to no avail. I have contacted support, so if I figure anything out I'll let you know.

Has anyone been able to fix this issue? It so deflating when you're all ready to push Go, then the Go button dissappears :cry:

chipmaker
Posts: 15
Joined: Tue Jul 21, 2015 2:36 pm

Re: GRBL Error: Cannot open port for Nomad

Post by chipmaker » Tue Oct 13, 2015 6:03 pm

I had a ton of problems with connection dropping. Support has been trying with best of intentions to get things fixed and I expect that they will take very good care of you. They sent me some troubleshooting a while back, but I have been so busy that I have not had time to implement what they said yet. I can say for sure though that they will be very helpful and attentive with your problem and will not leave you hanging, even if it takes some time to fix. At least that has been my impression... now I'll just have to let you know when I get around to fixing the thing! lol. Best of luck and keep us posted.

houndel
Posts: 21
Joined: Fri Apr 24, 2015 11:38 pm

Re: GRBL Error: Cannot open port for Nomad

Post by houndel » Wed Oct 14, 2015 12:37 am

I have been trying all the fixes noted here : http://www.shapeoko.com/wiki/index.php/ ... connection
...But no success yet. Moving the power plug for the spindle to another point in the room helped, but the issue still happens.

I'm running a 1.5KW air cooled chinese spindle, with industrial shielded power cable specific for motion control systems. The shielding is earthed.

Also tried moving the cables and a ferrite bead on the USB (just one I had lying around) but no clear change. I can get say 20% into a cut before it drops out, but once it drops out Carbide Motion will not connect at all to the Shapeoko 3, until I restart.

chipmaker
Posts: 15
Joined: Tue Jul 21, 2015 2:36 pm

Re: GRBL Error: Cannot open port for Nomad

Post by chipmaker » Wed Oct 14, 2015 12:48 am

Yep, I know that pain. It is a tough problem to chase because statistically it will work fine some of the time. From what I gather, the biggest cause is the static noise. I think at the end of the day, the control board is not hardy enough against the static. The best success I have had is in covering the control board shield with aluminum foil, essentially making a faraday cage. BUT, it will still happen, just less. There are some procedures for grounding the control board, but it is beyond my ability. I would contact tech support and be prepared to try a lot of stuff. For reference, I would not waste any time on the ferrite beads. For kicks, I literally put 20 something of them all along the router cable cord, the power supply to the control board. I also got a very nice $100 shielded USB cable... so I would skip all that, use the foil, and contact support about grounding. I need to get back in touch with them still to get my machine functioning. Right now this problem has got it sitting in the corner collecting dust.

jdw1865
Posts: 2
Joined: Wed Sep 30, 2015 11:08 pm

Re: GRBL Error: Cannot open port for Nomad

Post by jdw1865 » Wed Oct 14, 2015 2:34 am

Any chance there is a loose connection of the USB on the controller board? I got the same error when I inadvertently knocked my USB cable loose from my computer. Since many people have the same problem could it have been a bad batch of boards?

houndel
Posts: 21
Joined: Fri Apr 24, 2015 11:38 pm

Re: GRBL Error: Cannot open port for Nomad

Post by houndel » Wed Oct 14, 2015 3:06 am

Seems like this is a common issue: the more I dig and test, the more I find others posting similar symptoms.

I can complete a cut now, without dropouts. The solution (at least in my case and for now) was to route the spindle power directly out the top of my enclosure, controller power out the back left corner and USB out the front right. Stepper motor cables are bundled together and hang to the right side of the controller. Everything is as far apart as they can be. We'll see if this holds up on longer jobs. :?

houndel
Posts: 21
Joined: Fri Apr 24, 2015 11:38 pm

Re: GRBL Error: Cannot open port for Nomad

Post by houndel » Sun Oct 18, 2015 7:22 am

So far so good!

Support offered another solution which may be the definitive solution in my case: removing the stock aluminium shroud over the PCB.

I haven't had any dropouts since doing this. I guess the next thing I will make with the shapeoko is a non metallic shroud to protect the PCB.

Best luck to anyone else who comes across this issue!

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