a silly question...but...

gballard

OSNN Senior Addict
Joined
12 Dec 2001
Messages
549
Is there a limit to the length that a USB cable can be? The reason I ask is that I wouldn't mind being able to keep check on the new kittens via my webcam. I just don't know if there is a theoretical limit for the length of a USB cable that I would need to be able to do this with. Anyone know?
 

fantasi

My Yngy is My HoneY!
Joined
24 Jan 2004
Messages
307
forgive me if im wrong but i think you need a repeater...the signal would actually be lost after a long line. how long is the cable u getting?
 

fitz

Woah.. I'm still here?
Political Access
Joined
26 Apr 2004
Messages
4,084
Proper credit goes to: http://www.usb.org/faq/ans5

Q1: How long of a cable can I use to connect my device?
A1: In practice, the USB specification limits the length of a cable between full speed devices to 5 meters (a little under 16 feet 5 inches). For a low speed device the limit is 3 meters (9 feet 10 inches).

Q2: Why can't I use a cable longer than 3 or 5m?
A2: USB's electrical design doesn't allow it. When USB was designed, a decision was made to handle the propagation of electromagnetic fields on USB data lines in a way that limited the maximum length of a USB cable to something in the range of 4m. This method has a number of advantages and, since USB is intended for a desktop environment, the range limitations were deemed acceptable. If you're familiar with transmission line theory and want more detail on this topic, take a look at the USB signals section of the developers FAQ.

Q3: How far away from a PC can I put a USB device?
A3: With the maximum of 5 hubs connected with 5m cables and a 5m cable going to your full speed device, this will give you 30m of cable (see section 7.1.19 for details). With a low speed device, you will be able to get a range up to 27m, depending on how long the device's cable is. With a straightforward cable route, you will probably be able to reach out 25m or so from the PC.

Q4: I need to put a USB device X distance from my PC. What do I do?
A4: If X is less than 25m or so (see previous question), buy a bunch of hubs and connect them serially with 5m cables. If you need to go farther than that, put another PC, or maybe a laptop, out where you need the device to be and network it with the first PC using something that's intended to be a long-range connection, such as Ethernet or RS-485. If you need to use nothing but USB, consider using USB based Ethernet adapters to hook the PCs together.
 

gballard

OSNN Senior Addict
Joined
12 Dec 2001
Messages
549
well I am not buying any cable yet...just wanted to know if anyone knew..thanks for the info
 

Members online

No members online now.

Latest profile posts

hello peeps... is been some time since i last came here.
Electronic Punk wrote on Sazar's profile.
Rest in peace my friend, been trying to find you and finally did in the worst way imaginable.
Terrahertz wrote on Electronic Punk's profile.
Yo fellas!
Electronic Punk wrote on Sazar's profile.
Where are you buddy?
Perris Calderon wrote on Electronic Punk's profile.
Hey EP! All good with me, applying for Microsoft MVP right now, should have done this a while ago.

Notifications don't work, I only found your response by coming back to hunt up some threads, if you want, give me your email address so we can keep in touch easier!

Forum statistics

Threads
61,999
Messages
673,424
Members
5,593
Latest member
moussa021