A Dynamic Web Server
Many web servers only serve out static screens -- screens that are preprogrammed and do not change. But embedded controllers need dynamic screens for data exchange and control. So, make sure your embedded webserver implements a full HTTP server capable of dynamically generating HTML screens using current data. Your web browser will then be able to interact with the served pages, querying them using CGI scripts, and receiving replies with timely data embedded in the served screens. Add Mosaic's Ethersmart or WiFi Wildcards to the embedded controller of your choice for a dynamic web server.
"E.T. Call Home" Embedded Email Capability
Being able to browse into your instrument or product from a web browser isn't enough. Outgoing e-mail capability is essential so that your product can take the initiative to send out a message, in either machine- or human-readable form, to any designated recipient, even when it's not being browsed.
A Web-Served GUI
If your controller uses a Graphical User Interface (an LCD display and touchscreen) can it serve out the same GUI screen as a web page? You'll want to make sure you can interact with the instrument from a remote browser much like a local user can from the GUI. Using the same paradigm for user-interaction promotes ease-of-use, saves on training costs, and prevents the need for two different sets of documentation. Consider Mosaic's web-enabled embedded computers with touchscreen controlled user interface for your embedded webserver.
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CF Mass Memory
An intuitive user interface and easy web access appear simple on the outside but require lots of memory to store application web pages. Be sure your controller has access to mass memory such as removable compact flash modules.
Expandable, Modular I/O
You don't want to get locked into a vendor's embedded controller only to find that because you really need a 24-bit instead of a 12-bit A/D your instrument becomes obsolete. The controller should allow easy expansion of I/O, with pluggable I/O modules to choose from, and for that really offbeat customization, ready technical support and assistance.
A 10Base-T Physical Connection
10Base-T signifies a 10 Mbit/sec connection that allows you to plug your controller into any LAN that uses RJ45 connectors. These look like modular phone connectors, but are a little fatter. These connectors, and the cables they use, have become the de facto standard, more widespread and lower cost than the old fashioned coaxial cables. You'll also see 10/100Base-T offered, allowing data rates to 100 Mbits./sec. That may be good if you need streaming full resolution video, but generally the 10Base-T connection offers more than enough bandwidth, connects to most common LANs, and is rarely a communications bottleneck.
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