Over the last couple of decades, industrial equipment has used serial ports to read and write data mainly because serial ports are generally easy to use and provide an efficient way to transfer data. Use of serial ports, however, is limited: to access data, the host computer must be within 50 ft of the equipment, and only one computer can connect at a time.
Accessing Data Via the Internet
What if these limitations could be eliminated, allowing any authorized computer to access the serial data from anywhere on the Internet? What if this could be accomplished without requiring any software changes to your equipment's controller? Would you believe that your serial data could be viewed from a web browser?
All of this and more is possible by adding a device server to your serial port. The device server is designed to work transparently with your serial data by creating a network tunnel. On one end, the device server provides a network interface and allows the assignment of an IP address. It can be configured as a client (initiates the network connection) or a server (responds to a host computer connection).
On the other end, it sends and receives serial data to and from the open network connection -- in most cases, seamlessly. If necessary, several standard configuration options are available to help tunnel the serial data over the network. Once the device server is connected, the application can utilize all the benefits of a network.
Just how does this networked serial data get transmitted and received at the host computer? In many cases, an existing Windows application is used to open a COM port connection and read/write the serial data to the end equipment; however, the Windows application has no knowledge of a network connection. For such applications, Lantronix has developed a Windows driver called Com Port Redirector, which intercepts the data from the Windows application before it gets to the serial port and redirects the data to a configured IP address and port number. This allows legacy applications to utilize network data without requiring any software changes. For applications where data security is important, Lantronix offers a Secure Com Port Redirector™ (SCPR), which can encrypt the data using the standard AES encryption algorithm.
Device Server Options
Lantronix device servers are available in several form factors and configurations. One option is an external (gateway) module, a self-contained box that can be mounted and cabled directly to your equipment. This provides the simplest integration, with an RS-232 interface allowing a serial cable to be directly connected between the device server and your equipment, and in most cases, allows a network connection to be made in less than 30 minutes. External device servers are ideal for applications that involve network enabling installed or legacy equipment.
Embedded device servers integrate this capability into your equipment, providing a tighter integration and eliminating any external serial cabling, thus reducing the space required and allowing OEMs to automate the network configuration at runtime.
For most applications, it is easy to start with an external device server to get network features to market quickly. As volume grows, the move to an embedded device server can be made painlessly if the same configuration interface is provided for both products. This means OEMs will not have to make software changes as they migrate to higher volumes and more enhanced network features.
What About Wireless?
You may have noticed, however, that it is quickly becoming a wireless world. Lantronix offers both external and embedded device servers that allow serial data to be sent and received over an IEEE 802.11B wireless network. IEEE 802.11B is the same wireless network used by most notebook computers and PDAs to connect to the Internet. Employing a wireless device server enables the serial data can be connected directly to any local access points or hot spots (this is often referred to as infrastructure mode). They also can be configured for a point-to-point connection between a host or notebook computer and your equipment, often referred to as ad-hoc mode.
Many OEMs are now opting for a web server interface to their equipment, eliminating the need to develop and support Windows or Client applications. Almost every computer on the planet has one or more web browsers already installed, and are used to access data on a regular basis. How do you use your everyday application such as Netscape, Internet Explorer, or FireFox to access your serial data?
Once again, Lantronix device servers make that easy with a built-in Web Server. They also provide flash memory (non-volatile memory) for OEMs to store their own html content. If a browser is used to access the IP address and the assigned url of the device server, the stored html will be transmitted directly to the browser. To make the serial data available to the browser, you need to write some Java code and use CGI scripting, a practice often referred to as dynamic web pages. Using the same techniques, it is also possible to write data or configuration settings thru the web browser.
Device servers offer great flexibility and can save an enormous amount of engineering time when an application requires a network connection.
