Miscellaneous

USB 1.1 Versus USB 2.0

You have probably noticed that PC-based instruments are moving away from serial COM ports and parallel printer ports and are now mostly being offered with USB (Universal Serial Bus) ports. USB has many advantages over these earlier interfaces, including automatic setup in Windows operating systems, faster performance, and smaller and cheaper hardware.

USB is so easy to use that you don’t usually need to think about how it works. However, you might be confused by the two versions of USB that are sometimes advertised: USB 1.1 and USB 2.0. From a user’s point of view, the only difference between the two is speed. USB 1.1 supports only Low Speed and Full Speed modes, and is suited to slow devices like mice, keyboards and PC Data Loggers. USB 2.0 usually supports “Hi-Speed” mode, which varies in speed but is typically 20 times faster than USB 1.1. This makes it the best choice for fast devices, including PC Oscilloscopes.

Here is what happens when you connect a USB device to your computer’s USB port:

  • USB 2.0 port + USB 2.0 device: device works normally
  • USB 2.0 port + USB 1.1 device: device works normally
  • USB 1.1 port + USB 2.0 device: device performance is reduced
  • USB 1.1 port + USB 1.1 device: device works normally

Article: KB-147
15 Jun 2007

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