What is USB Type-B?
USB Type-B, or USB-B, is the squarish connector on the device end of a USB cable. The other end, a flat Type-A plug, goes into the computer or hub (the host). A standard Type-B plug is nearly square with two beveled corners on top. You'll find the matching port on printers, scanners, some USB hubs and docks, external drive enclosures, and audio gear such as audio interfaces and MIDI controllers. An A-to-B cable is what most people call a "printer cable".
Type-A and Type-B both date from the first USB specification. Giving the two ends different shapes keeps the host and device roles clear and stops you from connecting two computers together with a standard cable.
Type-B variants
| Connector | Description | Typical devices |
|---|---|---|
| Type-B (USB 2.0) | Squarish, 4 pins | Printers, scanners, hubs |
| USB 3.0 Type-B | Taller, with an extra section on top for the SuperSpeed pins | USB 3.0 hubs, docks and drive enclosures |
| Mini-B | Small and trapezoid-shaped | Older cameras, MP3 players and GPS units |
| Micro-B | Thin and flat | Older Android phones and accessories |
| USB 3.0 Micro-B | A wider, two-part Micro-B | Portable external hard drives |
Compatibility tips
- A USB 2.0 Type-B cable fits a USB 3.0 Type-B port and runs at USB 2.0 speed.
- A USB 3.0 Type-B plug won't fit a USB 2.0 Type-B port because of the extra section on top.
- A standard Micro-B cable fits one side of a USB 3.0 Micro-B port and works at USB 2.0 speed.
- Many newer devices use USB-C instead. To connect a USB-C-only laptop to a Type-B printer, use a USB-C to Type-B cable or an adapter.
Troubleshooting a USB printer connection
If a USB printer isn't detected, make sure the Type-B end is fully seated (it's easy to leave half-in at the back of a printer), try another cable and another port on the computer, and avoid overly long passive cables: USB 2.0 cables are limited to about 5 meters. Then check Device Manager and the printer driver.
For the CompTIA A+ exam
Core 1 (220-1201) objective 3.2 lists USB 2.0 and USB 3.0 cables and the miniUSB, microUSB and USB-C connector types, and objective 3.7 includes USB as a printer connection. Type-B isn't singled out, but you should recognize the squarish Type-B port on a printer and know that the Type-A end goes to the computer.