I have a Windows 7 machine in which I want to connect 32 devices which just dump logs out. But my machine doesn't allow me to connect more than 14 devices, at which point when I plug in any more it fails to recognize them. Is there a way to increase this maximum number? Do I need to add an additional USB controller?

Machine Configuration:

  • ThinkStation E31
  • 4 USB 3.0 ports, 6 USB 2.0 ports
  • Please don't cross post. I see that you have posted the same thing on Stack Overflow. – gparyani Dec 10 '13 at 21:13
  • 2
    From comments in the stackoverflow question, it appears the actual problem is running out of virtual COM port numbers to assign to the user's USB-serial devices. – Chris Stratton Dec 10 '13 at 21:32

One can connect up to 127 devices, including the hub devices, to a single USB host controller. I do not believe there is any limit to the number of USB host controllers, other than physical space and power limitations.

In your case, it sounds like a lack of power. Although 14 devices doesnt sound like much, they are probably drawing to much power and the 15th device is the "straw that broke the camel's back."

Try using powered USB hubs.

| improve this answer | |
  • Its is powered by USB hub only. Devices have its own power system. That is also verified. Its not consuming power from USB. Its USB-Serial Connection for collecting logs. – user2731159 Dec 10 '13 at 23:54
  • Did you verify the Device Descriptor of the USB2Serial? It could still claim to draw current from the USB - even if the actual device does not. But if you use self-powered hubs that would cause no problem because they have their own power supply. – Turbo J Dec 12 '13 at 13:56

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