Where to start?

Embedded Devices Plug N' Play
1

I am a Network Engineer and as of late, a very green web application developer. I work for a small company that has recently taken interest in connecting their proprietary microprocessor controllers to the internet. I am working with an engineer on this project that knows his hardware but hasn’t a clue about the software aspect of things.

What we have so far is this…Our Microprocessor board connected by the proprietary link to a board that the Engineer created that changes the signal and connector to RS-232 serial. That board is to plug into a Digi Connect ME board with the ethernet connector. We want to develop a web interface to read and change settings on our Microprocessor.

I’m clueless. I’ve never worked with embedded systems before. Am I in way over my head or is this something that a dedicated person can sit down and hammer out? Is there a resource in particular that would guide me in the right direction? Any advice would be helpful.

2

There are two basic types of Digi Connect ME modules available. One is the “S” or standard NDS (Plug-n-Play) module and the other is an “C” or custom module that runs on NET+OS, (Digi’s Embedded OS). You never mentioned which module you are using, so I listed a few options for both types. In order to help any further, I would need to know what type of module you are using and what version of NDS or NET+OS you have.

Actually having your own web page can be accomplished in one of two ways.

Using a standard (“Plug-n-Play”, NDS, Integration Kit) module is it possible to create a pseudo web page. Using “RCI over serial”, your application (typically a Java script running on the host PC) will issue RCI commands to the ME. Upon receiving the request data from the ME, your application will then construct and display a web page on the host PC.

Some excellent examples of Java Applets can be found within the ‘Digi Connect Integration Kit’ install. Below is the path on my system, your path to these examples may differ slightly.

C:\Program Files\Digi Connect Integration Kit\Samples\Applets\messenger

The second way, using the NET+OS development environment creates a real web page that resides on the ME. The easiest approach would be to utilize either the “Basic Web Server” or the AWS (Advanced Web Server). Using the AWS will allow the creation of much more robust pages.

If your application requires critical, high-availability usage of the web server, or if the application usage model includes multiple simultaneous web clients, and these clients require high availability, I would recommend use of the Advanced Web Server (AWS). The Basic Web Server (BWS) tends to starve simultaneously connected clients when servicing a particularly needy client. (One client can be a hog, and the BWS will not fairly arbitrate.)

In general, if web pages are minimal and can tolerate periods of unavailability, the BWS may suit your purpose. The advantage of the Basic Web Server is its ease of use. For simple web pages, it is easier to prototype the pages and generate the code using the HTML-to-C compiler versus PBuilder.

If strong security is a major concern, or requirement, use the MD5 authentication capabilities of the AWS. The BWS supports only Basic Authentication.

If the web server requires file system support, or if file upload capability is required, use the AWS. These features are not supported in the BWS.

If your applications intend to use cookies to track clients, use the AWS. Cookies are not supported by the Basic Web Server.

If multiple language support is required, the AWS supports multiple languages via a phrase dictionary. The BWS does not support multiple languages.

If the size of web content is an issue, the AWS has the ability to compress web content while the BWS does not.

If applications want to leverage CGI, then use the AWS. The BWS does not support CGI.

The chart below summarizes the features of the two NET+OS Web Servers.

See Chart attachment