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Limit On Usb Connections That Can Be Made?


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#1 drpepper55

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Posted 24 September 2008 - 09:52 AM

Hi all, I have a Dell Latitude CPX650 w/XP Home. My Dell has only 1 USB port in the back, it being of the 1.1 variety but I have been able to use 2.0 hardware to it and they have been compatible w/no problems for 3 years plus. I added a 4-port USB hub and have for the most part used 3 of those ports pretty much all of the time-and occasionally all 4- into my 1 on the back of the Dell for over 1-1/2 years now and also have had no problems. I bought a chill pad here recently that came with a built in 4-port hub in the base. If I connect the 4-port into 1 of the ports on the first 4-port hub, should I expect problems? Is there a rule of thumb or a common practice into how many ports can be extended from or put into 1 port? Thanks guys... :flowers: :thumbsup:

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#2 cryptodan

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Posted 24 September 2008 - 10:59 AM

Hi all, I have a Dell Latitude CPX650 w/XP Home. My Dell has only 1 USB port in the back, it being of the 1.1 variety but I have been able to use 2.0 hardware to it and they have been compatible w/no problems for 3 years plus. I added a 4-port USB hub and have for the most part used 3 of those ports pretty much all of the time-and occasionally all 4- into my 1 on the back of the Dell for over 1-1/2 years now and also have had no problems. I bought a chill pad here recently that came with a built in 4-port hub in the base. If I connect the 4-port into 1 of the ports on the first 4-port hub, should I expect problems? Is there a rule of thumb or a common practice into how many ports can be extended from or put into 1 port? Thanks guys... :flowers: :thumbsup:


The limit a few years ago was something like 123 USB Devices in one port.

#3 drpepper55

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Posted 24 September 2008 - 12:38 PM

You say, "The limit a few years ago was something like 123 USB Devices in one port. "

To that I say, "That's great, then I should have no worries if I'm only looking to try about 8 or so." I know, as I said, so far with having or using 4 I have not had any problems or major slowdowns that I can see. I just wanted to know if there was a limit, and if so, how many so I could anticipate if I might be pushing too far and if I could expect problems so as to plan better since what I have been using thr ports so far are for my cordless mouse receiving stick and 2 external harddrives and occasionally a 3rd thus using the 4 of the first 4-port hub or using the 4th one as my upload connection to upload songs/videos to my mp3/mp4 player and when I do I disconnect 1 of the hdds so I can free up a port. Now with what you tell me, I can rest easier knowing I'm good to go even if I use all 8 ports available to me. Thanks much...Best to you... :thumbsup: :flowers:

#4 cryptodan

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Posted 24 September 2008 - 12:48 PM

There was this school who gathered up 123 USB mac keyboards and connected them all together, and on the 124th one the link died.

#5 Romeo29

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Posted 24 September 2008 - 09:26 PM

There seems too be a maximum 127 device limit on a single USB 2.0 port.
It depends on whether your USB hub is powered or unpowered.
Also the devices/peropherals connected are powered or unpowered.
How much bandwidth and power the devices connected are drawing.
If a device cannot find the required bandwidth or power, it will be disconnected.

If the hub is unpowered then the limit falls down to 3-8 devices.

USB 1.1 has bandwidth limit of 12Mbps so this also reduces its connection limit and performance.
USB 2.0 offers data flow speed of 480Mbps
USB 3.0 offers data flow speed of 4.8Gbps (to be launched in 2009)

#6 drpepper55

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Posted 25 September 2008 - 10:28 AM

Cryptodan says, "There was this school who gathered up 123 USB mac keyboards and connected them all together, and on the 124th one the link died."

Now there's a challenge for the pc guy to go for...Now you're gonna start a war... :inlove: :trumpet: :cool: :thumbsup: :flowers:

#7 drpepper55

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Posted 25 September 2008 - 10:31 AM

Thanks for the interesting and valuable info, Romeo29. In my case my first 4 port hub I mentioned is unpowered while I believe my 4 ports on the chill pad are powered, I'll have to check. If they are I'll have to reverse my order of use to favor the powered ones and get better performance or less loss. Thanks again...Best to you... :thumbsup:

Edited by drpepper55, 25 September 2008 - 10:32 AM.


#8 usasma

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Posted 25 September 2008 - 03:47 PM

In general you'll know if the ports are powered because you'll have a plug to plug into the wall for the hub.
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