Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

If I have a USB printer, how does Linux or Windows manage the device when plugged into a different USB port? For example, I take a printer plugged into a front USB port on computer and move it to back port; Windows still recognizes that this is a printer already in use by system.

Is this just a special printer setting? A reason I ask is that I help a friend out with managing a control system (with USB digital I/O). We had to change computers out and I just plugged the USB ports into random open ports and the program still knew how to find the hardware (remember, entirely different computers)

share|improve this question
add comment

1 Answer

A USB device sends some data to the host machine called the device descriptor, which contains identifiers for:

  • The vendor of the product
  • The product itself
  • A serial number for the unit (this doesn't necessarily match the serial number marked on the device's casing)

The serial number is a way for the operating system to know whether it has seen a device before.

share|improve this answer
2  
And some devices lack of a serial number explains why they are seen as a new device when plugged into a different port. –  Richard Oct 5 '10 at 6:48
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.