[karla]

Maybe I unintentionally changed some parameters, but all of a sudden the Revo board will not connect and give telemetry data when using a USB cable from the GCS.
However, I can connect over the OPLM wireless link. But I need the USB link to be able to correctly save and load uae files.

Can you spot something wrong in the HW set up?
please se picture:

[f5soh]

There is no issue in this configuration, HID is set to Telemetry.

You can save all the parameters from your Revo over the radio link, except the OPLink settings if you use the builtin modem.
If using two OPLinks and you see the "receiver side" in OPLink tab all the remote (revo) are saved as well.

What do you get with a Rescue followed with a board connection ?

[TheOtherCliff]

Try another USB cable or test that one with a different device that needs both USB power and USB data.
Try another computer.
Finally, look for broken/damaged USB connector or maybe paint on USB pins, etc.

[karla]

I tried the Rescue and then connect but only got the same status when Rebooting it - no telemetry data. However, to my surprise, when trying the 3rd usb cable it suddenly kicked in to life and gave data. After that the first cable was also okay to use!?
Some dirt on the cables maybe. I dont know but so happy to get it working again... hope for ever.
Best
K

[mr_w]

While this might not be the issue you just experienced, but I am so surprised with amount of "charging only" usb cables that hit my desk - I do not really understand how sparing two thin copper wires for data lines saves that much on manufacturing costs, that somebody would actually make such crippled product?!

[TheOtherCliff]

With the 30 or so USB cables I have bought, mainly from cheap eBay, I haven't found any that are "only power", but I do have some that don't use correct specification cable and will only connect at USB 1.x speed.  I use those for making USB to servo cable so I can power a Revo and attached GPS using USB only.

For all but the stupidest USB devices now days, you must have data so the device can negotiate the amount of power it can use, else you get the dreaded "unauthorized charger" on your cell phone... 

While I am at it, another useful cable is from standard 5.5mm barrel power connector to Deans / XT-60 so you can use those 12V 1A power adapters to bench power your quad from the flight battery connector.  Easiest to plug in, and you can leave props on when testing / calibrating ESCs.