USB Cord maximum length

in General Discussion edited January 2014
DOes anyone know how long a USB cord can be before a repeater is required? Is 30 feet (10m) OK?



  • Reply 1 of 3
    applenutapplenut Posts: 5,768member
    Pretty sure it is 15 feet
  • Reply 2 of 3
    zozo Posts: 3,117member

    2: How long of a cable can I use to connect my device?

    A2: 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).

    Q3: Why can't I use a cable longer than 3 or 5m?

    A3: 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.

    Q4: How far away from a PC can I put a USB device?

    A4: 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.

    etc etc
  • Reply 3 of 3
    I would just like to comment on the information which has been availed on this website concerning usb (lengths).

    Thanks. Someone (Zo?) took the time to answer the question fully and concisely (glad you came up first in my search!).
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