none
USB Port/Device magic number limits RRS feed

  • 问题

  • As I was asked to post here so here it is.

    This is a rubber band question.

    Toshiba Satellite, USB2.0 x2; USB3.0x3

    Connected to the USB 2.0 ports are:

       1st USB 2.0 - an optical mouse (don't like glide pads)

       2nd USB 2.0 - Cooling pad with 3 extra usb 2.0 ports

    and USB 3.0 ports are:

    3rd USB3.0+recharge - Powered 7 port USB 3.0 Hub

       connected are: 2 mass storage device (2TB, 5TB), 2 Blue Ray drives, 1 powered, 1 non-powered 2-connections)

    4th USB 3.0 - Powered 7 port USB 3.0 Hub

        to each port is a single external mass storage device, (various 2TB -5TB drives)

    Now to attach a USB wireless broad band modem, with the capacity for another mass storage drive (micro SD card, but not actually present) to any available port (3 usb 2.0) or (2 USB 3.0).

    Wait for the internet to connection to happen and nada.  Instead get an error message claims that the number of USB devices has been exceeded, unplug a device not required.  (in this case 1 was sufficient)

    Then the secondary problem is I get a Code 38 after re-connecting a mass storage device, (device driver still resident in memory)  Solution is to reboot, cold start may result in it clearing, maybe after a few goes or try and trouble shoot the problems and get the "Windows had a problem, restarting message". and the device is happily recognized and everything works nicely until you have to disconnect a external hard disk.

    I know someone out there is going to say "you cant do that", "unusual configuration" which I got from a Microsoft employee 20 years ago when I configured 7 HDD on windows 95 machine.  In the process I made the observation that the operating system back then allowed for drives lettered A through Z, (26 drives in total!) and providing connections present 2 FDD, 24 IDE ports something more than easily achieved.  But a serious warning here do not ever partition any of the connected drives.  The OS could not tell the difference between a partition and a physical drive.  Format killed 2 drives not the partition being targeted.

    My question what is the magic number limit for the USB driver software for USB (xx)?  When can we expect an better solution that would allow the connection of hubs that exceed this above say by connecting a 13 port USB hub to each computer USB port.  In the above case we are talking 4 x13 port hubs (2 x13 usb2.0 and 2 x13 usb3.0) and because they can daisy chain. far more...

    2015年12月20日 8:08

答案

  • Hi Robert,

    I have read your question. Certainly, it has a limit for USB device drive in system by designed. However, it is pretty big. We haven't found an official article about the exact limiting number for the device. Maybe the link below could be help you, but we are not sure the accuracy of it due to we do not have the environment to test it.

    http://www.sevenforums.com/installation-setup/46201-limit-number-external-hard-drives.html

    http://www.w7forums.com/threads/a-limit-on-number-of-usb-hubs-in-windows-7.7006/

    Please Note: Since the website is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

    For your issue, there are many reasons affecting the limitations of the USB drive, such as power, USB driver and the port hardware itself, but not only the system.

    We would like to suggest you update the driver of the machine ports and BIOS. You need to download the latest driver from the official website and reinstall it. If it still doesn't work, you need to unplug the unnecessary USB drive and plug the one which you want to use.

    Wish you have a nice day.

    Best Regards

    Simon


    Please remember to mark the replies as answers if they help, and unmark the answers if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.


    2015年12月21日 5:29
    版主

全部回复

  • Hi Robert,

    I have read your question. Certainly, it has a limit for USB device drive in system by designed. However, it is pretty big. We haven't found an official article about the exact limiting number for the device. Maybe the link below could be help you, but we are not sure the accuracy of it due to we do not have the environment to test it.

    http://www.sevenforums.com/installation-setup/46201-limit-number-external-hard-drives.html

    http://www.w7forums.com/threads/a-limit-on-number-of-usb-hubs-in-windows-7.7006/

    Please Note: Since the website is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

    For your issue, there are many reasons affecting the limitations of the USB drive, such as power, USB driver and the port hardware itself, but not only the system.

    We would like to suggest you update the driver of the machine ports and BIOS. You need to download the latest driver from the official website and reinstall it. If it still doesn't work, you need to unplug the unnecessary USB drive and plug the one which you want to use.

    Wish you have a nice day.

    Best Regards

    Simon


    Please remember to mark the replies as answers if they help, and unmark the answers if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.


    2015年12月21日 5:29
    版主
  • Hi Robert & Charles,

    I'm having the same issue on a Win7 laptop with a bunch of usb devices attached.

    Got two hard external usb drives, mouse dongle, two hubs (one is 2.0 the other 3.0) and whenever I plug in a few more devices in any port (internal or hub) I get that dreaded "You have exceeded the number of port... blah blah..."

    And here's the kicker, it used to work up to 20 to 30 devices with no problems, just recently started complaining with as few as 10 connected devices.

    And yes I've done the usual, turn off/on the laptop, uninstalled/reinstalled the hubs and devices, tied pretty much everything.  It's quite apparent that there's some "magic" registry key which is causing all this mayhem.

    I will NOT reinstall Windows, since I have years of careful settings and apps installed which I'm not about to waste my time redoing.  Remember it used to work just fine with 20 to 30 devices, but now only about 10.

    Has anyone found a registry tweak or an app which could solve this annoying issue?

    Regards,

    BillA


    2019年8月8日 23:25