USB Cable Lengths

brainsmile · 01-12-2003, 11:33 AM

What's the maximum lenth a USB cable can be? In other words, is there a limit to how long one can be? I only see up to 15' and I really needed something longer. I know that they have those extending type of cables. That's ok but they are kind of ugly. I was hoping for about a 60' length if it still works.

TERRIBLETOM · 01-12-2003, 12:22 PM

At work i know we had to get two long ones and I want to say I thought they were 20' and we got them at compusa.

Dave_7 · 01-12-2003, 11:32 PM

I think five meters is the longest officially supported length for one cable. Otherwise, there may be some aftermarket products that extend that... though, maybe not.

Dave.

i6s1 · 01-12-2003, 11:43 PM

60' is way beyond spec, there are devices that convert it onto ethernet. Pretty expensive.

http://www.vpi.us/usbc5.html

Q2: 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.

Q5: I need to put a USB device X distance from my PC. What do I do?
A5: 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.

http://www.usb.org/faq/

01-12-2003, 11:33 AM	#1
brainsmile Chief of Naval Operations Join Date: Jun 2000 Location: woah... why is welfareloser here with me so early in the morning and more importantly why am I wearing her clothes?!? Posts: 13,754	USB Cable Lengths What's the maximum lenth a USB cable can be? In other words, is there a limit to how long one can be? I only see up to 15' and I really needed something longer. I know that they have those extending type of cables. That's ok but they are kind of ugly. I was hoping for about a 60' length if it still works. __________________ ********************************** DCM #1 (Founder) "Nobody beats Vitus Gerulaitis 18 times in a row." - Vitus Gerulaitis on beating Jimmy Connors after 17 failed attempts.

01-12-2003, 11:43 PM	#4
i6s1 Lieutenant Commander Join Date: Feb 2000 Location: Vancouver Posts: 905	60' is way beyond spec, there are devices that convert it onto ethernet. Pretty expensive. http://www.vpi.us/usbc5.html Q2: 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. Q5: I need to put a USB device X distance from my PC. What do I do? A5: 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. http://www.usb.org/faq/ __________________ YVAN EHT NIOJ Last edited by i6s1 : 01-12-2003 at 11:45 PM.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

01-12-2003, 12:22 PM	#2
TERRIBLETOM Commander Join Date: Dec 2002 Location: Boston, MA Posts: 1,261	At work i know we had to get two long ones and I want to say I thought they were 20' and we got them at compusa.

01-12-2003, 11:32 PM	#3
Dave_7 Captain Join Date: May 2000 Location: L.A..... Costa Mesa... Whatever, Man! Posts: 1,824	I think five meters is the longest officially supported length for one cable. Otherwise, there may be some aftermarket products that extend that... though, maybe not. Dave.

User Name
Password
Remember Me?