I had a hit or miss issue with my computer (windows) "seeing" my Garmin 520 when i connected to get updates, or download maps or courses or what have you. It turns out that not all of the micro USB cables i have scattered around are data cables. many are just cheap charging cables, and as such do not contain the full compliment of conductors. now I keep the dedicated data cable attached to my computer USB hub, so I can't screw that up again, and save me the frustration!