The EtherSmart Wildcard User Guide
Table of ContentsAppendix G: Hardware Schematic (pdf)
Appendix F: Browser Configuration
You’ll use a web browser on your PC to interact with the web server running on the EtherSmart Wildcard. Popular browsers include Microsoft Internet Explorer, Netscape based browsers such as Firefox and Mozilla, and other high quality free browsers such as Opera. All of these browsers work with the web demonstration program that comes with the EtherSmart Wildcard.
Additional considerations can limit the performance of some of these browsers if your application needs to serve out more complex web pages that require more than one TCP/IP connection per page. This can occur, for example, when mixed text and image data originating from the XPort are served out in a single web page.
The Lantronix XPort hardware on the EtherSmart Wildcard supports only one active connection at a time. However, the HTTP/1.1 standard (and consequently all browsers in their default configuration) expect the webserver to be able to host two simultaneous connections. A default-configured browser will try to open a second connection when two or more content types (for example, HTML text and a JPEG image) are present in a single web page. The second connection will typically be refused by the XPort hardware, causing an incomplete page load. The solution is to configure the browser to expect only one connection from the webserver.
This Appendix explains how to reconfigure Internet Explorer to work with any web page that the EtherSmart can serve out. For the best solution, though, consider downloading the free Opera browser and using it for all your interactions with the EtherSmart Wildcard.
To be able to browse mixed text and graphics pages from the EtherSmart Wildcard without modifying your default browser, go to www.opera.com and download the latest version of the Opera browser for Windows desktop machines. It's free, the download file is compact, and the install takes only a few seconds.
Simply go to www.opera.com and select “Download Opera”, then double-click on the resulting file to install the browser on your desktop. It is very easy to configure Opera for the EtherSmart webserver. Once Opera is installed, simply go to its Tools menu, and select:
Preferences->Advanced->Network->Max Connections Per Server
and enter 1 in the box. Now you’re ready to use Opera with the EtherSmart Wildcard dynamic webserver. The webserver is described in more detail in a later section.
The Lantronix XPort implements only one connection at a time. To serve mixed text and images or text and frames, or any mixed data types, HTTP/1.1 browsers expect the server to host up to two simultaneous connections. Internet explorer works well with the XPort if you set the registry key MaxConnectionsPerServer to 1.
To perform this browser configuration on your PC running Windows XP, you can (after backing up your registry):
1. Click Start | Run.
2. Type regedit and click OK.
3. Expand the directories HKEY_CURRENT_USER, then Software, Microsoft, Windows, CurrentVersion.
4. Click on “Internet Settings” to view its contents.
5. Check the right-hand column of the regedit window for the following line (value):
6. If present, right-click on the value (MaxConnectionsPerServer), select Modify from the drop-down menu, click Decimal, and set the Value data field to 1.
7. If the line (value) is not listed, right-click on the white region of Regedit's right-hand column, click New, and then click DWORD Value. Carefully type MaxConnectionsPerServer for the name of the new DWORD Value and press Enter. The new value should now appear in Regedit's right-hand column. Right-click the new value and click Modify. Click Decimal and set the Value Data field to 1, then click OK.
Unfortunately, there is a low-level bug in the code base of the Netscape-based browsers such as Firefox and Mozilla that prevents reliable operation with mixed image type web pages (such as mixed text and images served from the Lantronix XPort). The XPort does not increment its source port number with each exchanged TCP/IP packet, and Firefox and Mozilla rely on source port incrementing to properly order the received packets in time. The result is that some information is displayed in a skewed order by these browsers. This bug has been reported but has not been repaired. For simple single content type web pages such as those in the EtherSmart demo program, any browser including Firefox and Mozilla works well. For more complex mixed data type web pages, Opera is recommended: download it for free from www.opera.com.
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