USB to Ethernet Adapters
USB connections for peripheral devices have almost become an assumption in the past five years. The majority of electronic devices have a least one (and many times more) than one USB port built-in to the device to allow connections to other peripheries such as printers, cameras, external hard drives, MP3 players, phones, game consoles, network adapters, and more. The Universal Serial Bus (USB) hardware specification allows the connection between these secondary devices with the primary (normally a computer). Current USB technology has improved to the point that the external devices can be powered through the USB connection to include iPhones, iPods, other smartphones, and digital cameras and also support USB to Ethernet adapters.
When was Ethernet Invented?
Ethernet is a system for connecting computers using connecting hardware that includes collision detection. The invention is credited as being one of the most important supporting technologies for what has become the Internet the public uses today. Robert Metcalfe is credited with the invention while working for the research staff at Xerox at the Palo Alto Research Center (PARC) between 1973 and 1976.
During the time of the invention of Ethernet, Metcalfe was tasked with building a local networking system for the computers at PARC to be able to print to the first laser printer developed. To meet the challenge of the task, Metcalf had to solve the problems of the network being extensible across the hundreds of computers in the building and fast enough to send and receive information from the printer. Prior to this time, there had not this number of computers networked to a shared resource.
The date most commonly associated with Metcalfe’s invention of Ethernet is May 22, 1973 when he first annotated his thoughts on the potential of the technology in an internal memo; however, the first paper published on the subject by Metcalfe and David Boggs was in 1976, “Ethernet: Distributed Packet-Switching For Local Computer Networks.” After Metcalfe left Xerox in 1979, he was able to help convince Xerox, Intel, and Digital Equipment to promote the use of Ethernet as the industry standard. It has since evolved to being the most widely installed local area network (LAN) protocol in the world.
How Does Ethernet Work?
The Ethernet standard for LANs (local area networks) is the most prevalent networking standard in use today. Its primary function is to connect Internet capable devices to each other via Ethernet cable over a short distance. These devices range from printers, to routers, modems, personal computers, scanners, and more. Although there are alternatives to using Ethernet for networking computing devices by physical connection, it continues to grow in popularity across the world and finds support across all of the major computer operating systems. More recently, major computer manufacturers have included support for transferring information between two devices which support the standard.
When was USB Invented?
USB (Universal Serial Bus) was created in the mid-1990’s and later standardized in the formal release in November of 1995. The standard sets out the requirements for the connectors, cables, and communications protocols used to provide communication, connection, and power supply between a computer and electronic device. The standard development was a group effort between Compaq, IBM PC Co., Intel, NEC, Northern Telecom, Microsoft, and Digital Equipment Corporation who saw the need for a standard interconnect to help the computer telephony integration industry grow faster.
The primary motivator behind the design of USB was to standardize the connection of computer peripherals to include digital cameras, printers, portable media players, disk drives, network adapters, keyboards, and mice. Since then, it has become a common interface for connecting video game consoles, smart phones, and other mobile devices and has more than 6 billion ports and interfaces present in the global marketplace.
How Does USB Work?
USB is a peripheral bus specification which allows portable electronics devices to be plugged directly into a computer with the need for a specialized card inserted into the system. The Plug-and-Play technology allows computers that have USB ports to automatically configure support for a newly connected device once it is attached without restarting the computer. The current standard allows more than 100 devices (127 at the time of this writing) to be connected via USB at the same time on a single computer. USB ports can be located on the main computer tower, or even the computer keyboard or monitor which can now act as USB hubs.
When the computer host with the USB port(s) is turned on, it will send a query to all of the devices connected to the USB bus and assign each an address in an enumeration process. This process continues to occur after computer start, with the host primarily concerned with what type of data transfer operation the device is likely to perform. The supported USB data transfer types include:
Bulk transfer – Occurs with devices like printers that receive information in one large transfer. Blocks of information are sent to the printer over the USB connection (in 64 byte chucks or blocks), and then verified for correctness.
Interrupt transfer – Type of data transfer accomplished by a keyboard or computer mouse. The commonality for devices that use this type of transfer mode is the small amount of data sent.
Isochronous transfer – Devices that stream information like computer speakers use this mode. There is no error correction in this mode since the information is sent between the connected device and the computer host in real-time.
As more USB devices are connected to the host, it keeps track of the total bandwidth being requested by the enumerated devices. Up to 90 percent of the available bandwidth can be consumed by the connected peripheries (480 Mbs on USB 2.0, 4.8 Gbs on USB 3.0). Once the 90 percent threshold is reached, access to interrupt or isochronous devices will be denied. The packets for bulk transfers and control packets will get the left over bandwidth. USB bandwidth is divided into frames that contain 1,500 bytes with a new frame being initiated every millisecond. Each frame gives a priority to interrupt and isochronous devices to ensure they receive their guaranteed bandwidth. Control and bulk transfers are assigned to the left-over space in each USB frame.
USB Version History
At the time of this writing, there have been three major generations of the USB standard. The original pre-release occurred in November of 1994. The most current version of the standard, USB 3.0 came out in November of 2008 with a battery charging specification in 2010.
Prior to the first release of the USB standard in 1995, there were a number of pre-releases over the course of 1994 and 1995. These included:
USB 0.7: Released in November 1994.
USB 0.8: Released in December 1994.
USB 0.9: Released in April 1995.
USB 0.99: Released in August 1995.
USB 1.0 Release Candidate: Released in November 1995.
USB 1.0: Released in January 1996.
USB 1.0 mandated data rates of 1.5 Mbs for low bandwidth connections and 12 Mbs for full bandwidth. It does not include allowance for pass-through monitors (power and timing limitations) or for extension cables. There were not a significant number of devices which made it to market that used the 1.0 standard. The USB 1.1 standard update was released in August of 1998 and fixed a number of issues with the original standard. This would be the first version of USB to really be adopted by industry.
USB 2.0 was first released in April 2000 providing a much higher max signaling rate of 480 Mbit/second (effective rate of 35 MB/s) or high-speed. Starting with the second generation of the USB standard, changes or corrections to the standard were accomplished using Engineering Change Notices. Some of the significant changes to the USB 2.0 standard since first release included: Battery Charging Specification, Unicode support, Micro USB cables and connector support, and link power management to name a few of the modifications.
The USB 3.0 standard was released in November 2008 and provides a significant improvement in transmission throughput over past versions of USB to include speeds of up to 625 MB/sec or 5 Gbit/sec. These are more than 10 x faster than USB 2.0 even though they are rarely approached or tested by normal consumer use. Overall, USB 3.0 does reduce power consumption, time required to transmit information, and is backwards compatible with USB 2.0 by design. Version 1.2 of the Battery Charging Specification was released in December of 2010 to include a number of engineering changes such as allowing high speed communications while supplying current up to 1.5 A, setting a maximum current of 5 A, and allowing 1.5 A on charging ports for devices that are not configured.
How Does a USB to Ethernet Adapter Work?
An USB to Ethernet adapter is designed to do one task: connect a computer host’s USB port to an Ethernet cable. The advantage of the adapters is to let end-users connect one or many devices via Ethernet cable that can be run over a longer distance than USB cables with greater reliability. The adapter relies upon Plug-and-Play technology that will permit connection to the USB port followed by subsequent Ethernet connection. The Ethernet cable is then plugged into the periphery computer or device to communication via application, share a network or Internet connection, or to transfer information directly.
Why Do You Need a USB to Ethernet Adapter?
USB to Ethernet adapters are finding a number of applications in the home and in industry. Since Ethernet cable runs can be significantly longer than USB cables, they can be used to connect two computers to share information. This information can be an Internet connection, direct sharing of information, or shared application data. Bridging an Internet connection between two computers has seen a fair amount of use in the past several years when technology or security policy precludes one of the two computers from obtaining a local Internet or network connection on its own.
Advantages of Ethernet over USB
Except for cases where required connection runs of cable are extremely short, Ethernet cables have a number of advantages over USB. The Power over Ethernet (PoE) standards requires a more elaborate power scheme than USB 2.0 or 3.0. It operates at 48 V DC and can supply more power over a cabling length of 100 meters than USB 2.0 can accomplish in 5 meters. The Ethernet standard also has a greater safety margin than USB requiring electrical isolation between networked devices up to 1500 V AC, 2250 V DC for 60 seconds. Since USB was not designed as a solution for longer cable runs (ie only for computer peripherals that would be close to the host computer which it relies upon for ground), Ethernet has a large safety advantage over USB. This is especially true when connecting to cable or DSL modems that can see hazardous voltages under fault conditions from external wiring.