EMI and USB connection

Well, i'm using a homemade RAMPS 1.2 for my electronics and had problems driving my printer. Suddenly printer would stop working and pronterface would crash. I contacted kliment and after his help i noticed this message on my ubuntu machine:

output form the 'dmesg' command:

[32608.528022] usb 5-2: new full speed USB device using uhci_hcd and address 7
[32608.731078] cdc_acm 5-2:1.0: ttyACM0: USB ACM device
[32907.040053] usb 5-2: USB disconnect, address 7
[34082.292440] usb 5-2: new full speed USB device using uhci_hcd and address 8
[34082.494101] cdc_acm 5-2:1.0: ttyACM0: USB ACM device
[35401.672056] hub 5-0:1.0: port 2 disabled by hub (EMI?), re-enabling...
[35401.672064] usb 5-2: USB disconnect, address 8
[35401.924035] usb 5-2: new full speed USB device using uhci_hcd and address 9
[35402.124366] cdc_acm 5-2:1.0: ttyACM1: USB ACM device
[42725.360056] hub 5-0:1.0: port 2 disabled by hub (EMI?), re-enabling...
[42725.360062] usb 5-2: USB disconnect, address 9
[42725.612024] usb 5-2: new full speed USB device using uhci_hcd and address 10
[42725.814956] cdc_acm 5-2:1.0: ttyACM0: USB ACM device
[42788.848057] usb 5-2: USB disconnect, address 10

ElectroMagnetic Interference seems to be the problem and it could set the device on parameter to off so pronterface was loosing connection with printer.
That problem became noticable when i was sitting next to the printer and 2 times in the same day that i stood up for 5' printer would crash.
In order to maximize the phenomenon, i used a copper ring through the USB cable near the +12V. The result was really interesting! Pronterface in monitor mode wouldn't get data for the extruder's thermistor or better, it read that it was grounded!

Well, after this test i remembered that through +12V supply the current is in class of Amperes, so EMI isn't so weird.

In order to eliminate EMI i twisted the wires of +12V, the heaters' and ofc the motor wires.
Also i used a USB cable with ferite ring.

Now i'm checking if there is also any other problem.
I didn't found anything inside the forum in my first search so i thought that it may help others.

i know people will get that from the stepper motor wires, if there endstop cables are ran beside them.

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[mike-mack.blogspot.com]

dissidence Wrote:
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> i know people will get that from the stepper motor
> wires, if there endstop cables are ran beside
> them.


Indeed.