Many of today’s test applications require the transfer of large amounts of data from instrument to PC. When choosing instrumentation, you need to know which transfer rates your PC supports. The USB standard provides four data transfer rates:
- Low-Speed – Data transfer at 1.5 Mb/s. Devices such as mice and keyboards typically use this lowest transfer speed. This was part of the original USB 1.0 standard.
- Full-Speed – Data transfer at 12 Mb/s. Until the introduction of Hi-Speed USB in 2000, this was the fastest transfer speed for USB. This was also part of the original USB 1.0 standard.
- High-Speed – Data transfer at 480 Mb/s. Introduced in the Hi-Speed USB standard (USB 2.0), the high-speed transfer rate made USB a viable option for sending large amounts of data such as audio and video.
- Super-Speed - Data transfer at 1 Gb/s. This was introduced with the USB 3.0 standard.
Every successive USB standard has maintained backwards compatibility with older standards. While the USB 2.0 specification introduced the high-speed transfer rate, it also maintained backward compatibility with the lower-speed rates, as did the USB 3.0 with it's predecessors. As such, devices are often called USB 3.0-compatible while only supporting the low, full, and high-speed transfer rates. When purchasing new instrumentation, look for the phrase “Super-Speed USB” to ensure that the instrument can support the fastest transfer rates.