Losing Connection in Middle of Project

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MikeD
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Re: Losing Connection in Middle of Project

Post by MikeD » Tue Sep 29, 2015 1:13 am

Does any one know anything about isolation transformers?

http://www.amazon.com/Tripp-Lite-Isolat ... ransformer

Will that keep the connectivity issue from happening?

Could this be a symptom of the hobby level power supply that is provided? I am used to using either really heavy transformer style power supplies or fancy DIN rail mountable 24vdc switching power supplies. Pretty much all of them are substantially more robust feeling than the little guy provided with the shapeoko.
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cvoinescu
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Re: Losing Connection in Middle of Project

Post by cvoinescu » Tue Sep 29, 2015 12:49 pm

That transformer is unlikely to help, IMO.

The power supply may be a factor, sure, but a good EMI filter should take care of that. I remember at least one person said they would buy one and try it, but I don't recall reading about success with that approach at all.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

MikeD
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Re: Losing Connection in Middle of Project

Post by MikeD » Tue Sep 29, 2015 1:03 pm

Cvoinescu, how did you go about "galvanically isolate the machine end of the USB cable"? Did you use a little device like this?

http://www.cooldrives.com/index.php/usb ... oC7S3w_wcB

Thanks,

Mike
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WillAdams
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Re: Losing Connection in Middle of Project

Post by WillAdams » Tue Sep 29, 2015 1:28 pm

He made a custom board which he sells on his shop and shouldn't be so reticent about:

http://store.amberspyglass.co.uk/gaups- ... d-kit.html
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

umkfr
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Re: Losing Connection in Middle of Project

Post by umkfr » Tue Sep 29, 2015 1:51 pm

Hello !

I just received my SO3 last week and I had the same issues. Losing connection in the middle of the job, maybe related to the fact that some electrical material was starting (fridge or garage door opener). I had a line rectifier and I tried it and all the problems disappeared !

Here it is :

http://www.ldlc.com/fiche/PB00030988.ht ... 2BShopping

I couldn't have a job done without problems and after using the APC box, I didn't get any issues anymore. SO for me this THE solution !

Hope it helped !

cvoinescu
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Re: Losing Connection in Middle of Project

Post by cvoinescu » Tue Sep 29, 2015 1:53 pm

I don't sell it, at least not yet.

I had PCBs made and built a prototype, which works perfectly for me. I also bought an off-the-self ADuM4160-based USB isolator to test (same chip used in the product at MikeD's link, only mine was cheaper because it came from China, was just a board without an enclosure, and did not pass along power). I haven't gotten around to testing that USB isolator.

A few years ago, when I first tried this, I just used 6N137 optocouplers between an USB-to-serial adapter and the Arduino, but @veng pointed out the Analog Devices ADuM1301 was cheaper and better than three 6N137s, so I used that in my prototype.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

MikeD
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Re: Losing Connection in Middle of Project

Post by MikeD » Tue Sep 29, 2015 2:55 pm

umkfr,

Thanks for the tip. The UPS I tried has a similar system built into it, a line regulator that keeps power with in 8% of the set target. When still plunged into the wall I was getting connection interrupts as per usual. I believe the spikes are to fast for the unit to react. However, to no real surprise, when unplugged from the wall running on battery only, no problems occurred. I think I'm going to try a device that will fully and continually isolate the power from the grid. something like McMaster-Carr P/N 70245K72.

http://www.mcmaster.com/#70245k72/=z5ebz7

I'd also like to try a different power supply for the SO3. Does anyone have the PIN out for the input power connector? It is a 4 pin connector but seems like i'd only really need 2 pins to give it the 24vdc its after. I have a handful of 24vdc power supplies sitting around from Automation Direct that I use to power PLCs and stepper systems on other machines I've built.

Cheers,

Mike
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rtlflatt
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Re: Losing Connection in Middle of Project

Post by rtlflatt » Tue Sep 29, 2015 4:46 pm

Probably 2 pins for + and 2 for -. Carry more current. Might be wrong
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MikeD
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Re: Losing Connection in Middle of Project

Post by MikeD » Tue Sep 29, 2015 5:41 pm

Ordered this guy:

https://www.olimex.com/Products/USB-Mod ... SB-ISO.pdf

Going to see if that solves it... will be sure and let y'all know...

Meanwhile the UPS is going back to the store. My limit switches will be here tomorrow, along with a bunch of wire routing/ducting, 9mm belts, and Z-Axis plate reinforcement brackets. Should be a whole new machine come Monday.
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veng1
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Re: Losing Connection in Middle of Project

Post by veng1 » Wed Sep 30, 2015 12:04 am

If you run the computer, SO3 and router all off a UPS, the noise will still be able to travel along the AC wiring and the only thing accomplished is a system that still won't work but will survive power outages. All the noise paths still exist.

If the noise is conducted along the AC line and is from the router, then a UPS with the computer and mill plugged into it and the router plugged into the wall might help as the UPS has some noise isolation and filtering built in. But instead, it might give the same results as replacing the UPS with a power strip with built in filtering with the computer and mill plugged into that still with the router plugged into the wall.

The SO3 power supply may or may not pass high frequency noise depending on it's specification. Typically a Class 2 UL rated supply is transformer isolated and only passes a small amount of noise by parasitic capacitance through the small, high frequency transformer. However, I've seen designs that bridge the input neutral to the output ground with a large value safety rated cap. I don't know why and personally think it doesn't belong there. The biggest problem is determining if something like that is there which requires measuring with a capacitance meter, tearing it apart and looking or just try different power supplies and see if it fixes the problem.

Sometimes just grounding everything to everything works with fairly low impedance wires. That is how RF is usually done.

If the noise is traveling along the USB cable, then an galvanic isolator like like @cvoinescu is describing is the best bet. I'm looking forward to seeing what his final design does and if it has a few optical isolated switch inputs. Subtle hint here...

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