Ethernet interface

There are various modules on the market for connecting devices to ethernet LANs.

Some are Arduino-specific, i.e. the shield from Sparkfun, DEV-09026, $46.

Others seem to be "generic", and connect (on the device-to-connect-to-LAN side) via a serial interface. (Are there other options?). The Sparkfun /WIZnet Serial-to-Ethernet Gateway looks distinctly cool, especially at $30, complete with built in webserver.

Pros and cons? I always prefer a simple, general answer. I use ModernDevice RBBBs, anyway, so a shield's easy "plug in", the easy management of the physical problems of connection are not going to help me, anyway, are they?

Are there other advantages to a shield that I'm missing?

What should I look for in an Arduino to LAN module?

I don't mind having to configure the module "the hard way", i.e. by connecting it up to a big PC and setting a fixed IP address, etc.

Thanks, Tom

The arduino ethernet shield has libraries made for it. You can get it working in a matter of minutes.

Google for 'arduino ' and whatever device you're looking at to see how well supported it is. You may find a little more money will make it loads easier to use. You might not though. Have a google.

The Wiznet WIZ811MJ module is great. Basically the same as the Arduino Ethernet shield, cheaper, without SD and Ethernet library compatible.

I'll second tep's suggestion. If you look at ladyada's Ehternet shield, you'll find it's actually using the Wiznet module. And it's fully compatible with the standard Ethernet libraries. Which can be a big plus compared to, say, the ENC28J60 that some people are using because it's cheaper. The Wiznet doesn't need many connections to the Arduino, so it's not a big hassle to wire one to something like the RBBB.

Based on my experience, I recommend that you wire the modules so the Wiznet reset is done under software control, using a digital pin. It's a bit of a bummer to "waste" a pin for that, but it enables you to create systems that don't have to have the reset button pushed to recover from networking problems.

Another plus, compared to the serial-to-Ethernet, is that you can build custom webservers and clients that interact directly with the Arduino hardware, instead of going through serial port messages. Or even both: I have a system running now that gathers weather data at a remote site, and posts it to an SQL database on a PHP-based server hundreds of miles away. At the same time, it's running its own small webserver, so I can surf in and check on how it's running without needing to drive out into the desert. I could do the "monitoring" part via a serial-to-Ethernet, but I doubt I could do the client: I'd probably need to create a PC app to communicate via the virtual serial port and act as the web client.

Wiznet has a U.S. mail-order site where you may be able to find a better deal on the modules. They happened to have a nice sale on the WIZ811 modules when I bouoght them last year, and I got 3 modules for about the price of two from most other vendors. Plus they carry stuff that few (maybe no) vendors stock.