Although the RS-232 (EIA-232) serial port is quite ubiquitous, it does not solve all communication and connectivity problems. Most notably, RS-232 has distance limitations, and even RS-485 and RS-422 are limited by distance. Also, it's a little difficult to share a single RS-232 cable from a device to a PC amongst users of multiple PCs without physically detaching and re-attaching the cable or using a switchbox.
In (partial) solution to all these problems come a wide variety of products all generally classified as Serial-to-Ethernet converters. Some of these products are quite simple and limited in functionality, while others are very sophisticated.
"Roll Your Own" - A number of companies, including Rabbit Semiconductor, Zilog, and Netburner offer off-the-shelf microprocessor modules with one or more serial ports and an Ethernet connector. They all come with sample applications, but they all require some amount of programming to make them functional, not to mention needing a case, power, supply, RS-232 line drivers, etc.
"Terminal Servers / Console Servers" - Companies like Cisco, Cyclades, and many others offer products that support tty-type connections (i.e., like you'd use with telnet), and have a number of other features. If the serial device that you're connecting to requires special software on your PC (my temperature sensor did, for example), then this sort of product is not for you. However, if you just require a terminal interface, you may want to consider this type of product.
All of the above products are fine if you're connecting on the same local-area network. However, if the serial device is remotely-located, possibly behind another company's firewall, you may have a more interesting challenge. Getting a company to change their firewall to allow incoming connections to a terminal server installed by you (a third party) is a daunting task, if the network administrator is very security-conscious. Also, if the TCP port that you want to use for the (incoming) connection is already taken, you're out of luck.
If you're trying answer the following questions:
 | How do I connect to my PBX over the Internet? |
| How can I deploy a dialup modem replacement solution to cut long-distance cost without changing other parts of my system? |
| How do I connect to my elevator over the Internet? |
| How do I remotely connect to my serial-enabled device over the Internet? |
| How do I capture data from my oscilloscope over the Internet? |
| How do I monitor my lab experiment from home? |
| How do I connect to my air conditioner from a remote location? |
| How do I monitor serial communications from a distance? |
| How do I interface with my industrial controller once it's deployed at a customer's site? |
| How do I send/receive not just the TX/RX signals, but ALL the RS-232 control signals over a long distance? |
| Can I do any/all of the above without any changes to my already-written application? |
then read on. There's hope for you yet!
The Traversix connectivity product family offers a complete end-to-end solution for securely connecting to legacy serial devices over the Internet without having to change your existing serial application, and without requiring any special firewall configuration. This is achieved by installing the Traversix Connectivity Server at the remote location, and installing the Traversix Connectivity Client on your PC. These two products connect to the Traversix Connectivity Gateway, and allow seamless communication between your PC and the serial device, whether it's in the next room, or on another continent.
Also, because the Connectivity Client creates a virtual serial port on your PC that behaves just like a hardware serial port (i.e., COM1, COM2, COM3, etc.), it is completely compatible with any existing serial application. What could be simpler!!!
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