ETHERNET The Serial Revolution: Establishing Global Access to Serial Ports

In the process of updating a variety of computer systems and hardware configurations, the plant manager of a Midwest manufacturer needed a centralized network that would connect three buildings within three quarters of a mile, plus a couple more several miles away.

With a wide array of legacy equipment, primarily utilizing serial connections, the need presented a rather complex challenge, especially since serial connections are limited in terms of distance and networking.

The scenario is not uncommon. In fact, as computer software and hardware technologies advance, a massive connectivity gap is growing between perfectly good legacy systems and advanced Data Acquisition (DAQ), Programmable Logic Controllers (PLC), Industrial Computers and other critical systems.

Here are the challenges serial technology faces:

* Limits on linking remote equipment or networks,
* The number of potential connections is lower,
* Monitoring and control of remote equipment is more difficult,
* Upgrading software and firmware must be handled locally, and
* Various types of networks can’t talk to each other.

With recent advances, it’s now simple, fast and inexpensive to connect any number or type of serial equipment to an Ethernet network. The solution is utilizing Ethernet Serial Servers to make connections, manage traffic, and extending data signals to anywhere in the world.
History of Serial Communications

Serial ports were first used in 1960, and the first versions of RS-232 approved in 1969. The standards were intended for communications equipment such as phone modems, and serial interfaces were called COM ports.

Current maximum serial port speeds are 20 kilobits/second (Kbps) for RS-232 and 300 megabits/ second (Mbps) for RS-422/485. Distance limits are typically 50 ft. for RS-232 and 4,000 ft. for RS-422/485, though repeaters may extend this. The top number of devices for a serial LAN is 32; more can be connected with repeaters, up to the address limit (usually 256) of the devices used.

For years, advances in serial technology developed along with the equipment being connected. There are still many uses for serial devices, and the huge inventory of equipment, cables and software proves its success. Without question, serial connectivity remains the standard in a wide variety of industrial, commercial and medical applications

Even so, external serial ports are no longer standard on PCs. And serial technology is no longer a prime focus of development and progress. Herein lies the technology gap that is effectively bridged by Ethernet Serial Servers.
History of Ethernet LANs

In November of 1969 the U.S. Dept. of Defense sponsored a trial linking computers at UCLA and Stanford. It was the first effective joining of computers using different operating systems using the same communications protocols. This was accomplished over standard phone lines and with data speeds of 50 Kbps. It was the first true network operating system, and the predecessor of the Internet and Ethernet.

More computers were added, and eventually other networks developed and were linked. Research improved the technology. In 1974, basic principles of what was called the Ethernet were proposed and by1976 the first Ethernet was deployed, running at a speed of only 3 Mbps.

In the 1990’s, the Ethernet became the most frequently used of all local area networking (LAN) types, due to its speed, cost, versatility, dependability and ability to connect a variety of other network systems and equipment.

While the speed at which Ethernet can transfer data continues to increase, these blazing speeds have relatively little impact on moving serial originated data, where speeds are typically gauged in kilobits, not megabits.
Introduction to Ethernet Serial Servers.

Recently developed Serial-to-Ethernet technology makes it possible to connect serial devices using the Ethernet as a bridge. The cabling, hardware and software that accomplishes this is called Ethernet Serial Servers (or just Serial Servers for short).

Here is a simple layout of what might be accomplished when Ethernet is utilized in making connections: