Comments on: How to identify USB cables?

Question: How to identify USB cables?

nowonmai — Sun, 07 Oct 2007 07:58:27 -0800

I have about a million USB cables. How can I tell which ones are USB2 and which are USB1, and is there really a difference?

By: niles

niles — Sun, 07 Oct 2007 08:00:38 -0800

The USB 2.0 Myth.

By: shepd

shepd — Sun, 07 Oct 2007 08:10:01 -0800

I have some dollar store cables that do not work at USB 2.0 speed; connected devices, after erroring out, fall back to USB 1.0 speed (or lock up, depending on how poorly they're built). This is in linux, I don't know if windows would fall over or not in this case.

I would simply test them with something like an external hard drive, move a lot of data back and forth, and see if there's too many errors. Not sure how seeing the errors would work in windows, but I'm certain someone will suggest a way.

By: curiousleo

curiousleo — Sun, 07 Oct 2007 10:34:38 -0800

unless you have old usb cables that has little bulging plastic things near the connectors ..(like older generation scanners that comes with..)

you should be o.k... almost all recent (since few years ago) are USB 2.0 even if it doesn't say so..

By: spiderskull

spiderskull — Sun, 07 Oct 2007 11:25:31 -0800

niles has got it. The cables are theoretically supposed to be identical, but due to its slower speed, USB 1.1 isn't as sensitive to non-spec cables.

By: nowonmai

nowonmai — Sun, 07 Oct 2007 12:17:25 -0800

What's the deal with the bulgy things on older cables?

By: smcniven

smcniven — Sun, 07 Oct 2007 13:13:30 -0800

nowonmai: They are ferrite beads

By: Pinback

Pinback — Sun, 07 Oct 2007 19:10:48 -0800

The cables are theoretically supposed to be identical ...

Not quite true. The USB 1.1. spec says a maximum length of 3m; USB 2.0 spec says maximum of 5m. IIRC the original, never-widely-adopted, USB 1.0 spec said a maximum of 850mm.

There's a whole lot more to it than that, mostly to do with propagation delay and signal rise/fall times (both related to cable reactance) and allowable device response time, but what it boils down to is this:

If it's got a ferrite suppressor on it, it's definitely USB 1.1 (or, just maybe, USB 1.0)
If it's between 3 ~ 5 metres, it should be a USB 2.0 cable (notwithstanding dodgy manufacturers making 'long' USB 1.1 cables)
If it's < 3m long, treat it as a USB 1.1 cable - though you might be able to get it to work at USB 2.0 speed if it doesn't have a ferrite suppressor, particularly as long as you don't daisy-chain devices or hubs.

By: nowonmai

nowonmai — Sun, 07 Oct 2007 19:30:49 -0800

Thanks folks. All the cables are less than 3m, and I forgot to say that I am using a Mac, but I have learned a lot and can throw out the ones that won't give me a 480Mb/s connection to my device.