Extending USB cables

[gmh265]

I am trying to extend a usb cable link approx 20m and I understand this may not possible with just a normal usb cable, that boosters should be used. Is this correct and does anyone know of a good brand of usb cable booster?

Thankyou

 

[Snoogans]

I'm think the length limit is due to timing requirements in USB communication. A 30ns propegation delay is allowed (I think, its been a while). I learn't this stuff in 3rd year of uni, and we only covered USB 1.0 and 1.1, 2.0 hadn't become common yet. So I could be wrong.

 

[VEBill]

Instead of looking for "boosters", look for USB Hubs. They're relatively cheap and you can ignore the additional ports.

 

[johnwm]

Max distance from host to peripheral is 5m due to propagation delays. See:

http://www.intel.com/technology/usb/faq.htm#usb19

Good Luck
johnwm
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[leonar40]

Yes I think that you are going to have a problem extending the USB cable that far. Perhaps the instrument or whatever you are trying to communicate with can use GPIB instead of USB? It's slower, but it can go a lot farther, and you can have many instrument in the same GPIB chain.

 

[VEBill]

Lots of hits on "USB Extenders"...

Here is one example:

http://www.kvms.com/black box/blackbox_usb_extenders.asp

They typically use CAT5 cable to go up to 300 feet.

 

[gmh265]

Thanks everybody, USB extenders are on the way

 

[johnwm]

Just note that the boosters don't work like a standard 2-way USB due to the timing issues discussed - they work like 2 separate 1-way serial busses, so for most USB 2 devices your 2-way communication will slow down dramatically

Good Luck
johnwm
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[advidana]

I use a usb extension core to about 30 to 35 ft with a video camera using to Two different computers, any further then I lost the signal there was a differnce of 5 ft between computers used, I think it was due to voltage drop between the camera and the computer not the video db lost since I used the same cables. Anyway I a use a USB booster I found at fry's electronics and a could go at least 30 more feet. I did not go any further because I was using it to monitor the front door from my office in the rear and that length did the trick.

 

[AlanMog]

You need to go to

http://www.icron.com

They have the world's only "approved" USB extension technology that works for both USB1.1 AND USB2.0 and can extend proper USB signals 330 feet over standard Cat5 or, 2km over fiber. They have USB Rovers (the least expensive), USB Rangers and have several OEMs who embed their ExtremeUSB technology into their own products. I've heard they work extremely well.