USB 3.0 has gotten off to a slow start in commercial areas such as consumer electronics, in part due to timing introduction issues and the economy. But according to Brian Foster, a product manager for B&B Electronics, acceptance is picking up as people see more and more requirements for high bandwidth operation.
Since the key advantage of USB 3.0 technology is really fast data transfer speeds, one area in the industrial marketplace where the technology is making its presence known is in machine vision applications where it is a primary immediate driver.
Three generations of USB
USB has gone through several revisions. When specifying equipment, it’s important to tell them apart and to understand how each revision has affected USB. USB 1.1 referred to “Low Speed” and “Full Speed,” while USB 2.0 added “High Speed,” which is faster than “Full Speed.” USB 3.0 adds “SuperSpeed” to the mix.
This chart shows the actual data rates:
The three generations of USB offer dramatically different bandwidth performance.
(Source: B&B Electronics)
While each version of USB is backwards compatible with its predecessors, it can’t make devices designed for earlier versions of USB go any faster. The result is that a USB 3.0 port is quite capable of communicating with a USB 1.1 or USB 2.0 device, but only at the speeds supported by the device itself. The reverse is also true. A USB 3.0 device attached to a USB 2.0 port can only operate at USB 2.0 speeds. To get full USB 3.0 speed, both the host USB port and the connected device would have to be USB 3.0 capable.
USB 3.0 also adds more than raw speed to the specification. It provides more power to downstream devices and “smart charging” functionality. Earlier versions of USB could not tell whether a device was connected to a USB port or whether a connected device was active. So power was supplied at all times. USB 3.0 reduces power to a port if no device is connected or if a connected device is idle.
USB in industrial automation
“USB used in industrial automation or other commercial environments is typically used to interface with a device such as a programmable logic controller,” Foster told Design News:
That is where we found a niche by providing USB connectivity to serial converters. The user can take their laptop computer, which doesn’t come with a serial port and use RS 232 or 485. When there is a need to connect to that type of device, you are often dealing with different ground planes, and there is a potential of damage to the PC by the ground loop that can be caused. By adding isolation to our USB products, it provided a safe connection to serial converters.