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WI B Pt.3: By MAURO GRASSI Web S erver I n a B ox In Pt.2 last month, we showed you how to connect the WIB to a network and gave the step-by-step setting-up details. Most constructors will settle for the website provided but for those with special needs, this third article is for advanced users who want to customise the WIB to their requirements. O NE OF THE advantages of the WIB is that you can customise it by designing your own website if you wish. For the purposes of this article though, we’ll assume that you know the basics of website design. Instead, we’ll just give a few basic pointers on dynamic content and running CGI (Common Gateway Interface) commands. Designing your own website Basically, it’s up to you whether you use the website we have provided with the WIB or one of your own design. It’s Note: the three tables referred to in the text (Tables 1-3) are too large to include in this article. Instead, you can download them in PDF format from the SILICON CHIP website.You’ll find them in the downloads section for Jan 2010. just a matter of copying the website you wish to use to the memory card. When it comes to designing your own site, the best thing to do is to first examine the website we have provided and look at the source. We have used dynamic variables, as well as forms and Javascript. There are plenty of HTML introductory tutorials on the web. Also you can use a freeware HTML WYSIWYG (What You See Is What You Get) editor such as Kompozer which you can download from http://kompozer.net We used Kompozer to design the website provided with the WIB and you can change all its important settings if necessary. Dynamic content The WIB implements a simple system for dynamic content. For dynamic pages, a string of the form ~XX, where XX represents a hexadecimal code between 00 and FF, is replaced by the value of that variable. Table 2 on the SILICON CHIP website gives a list of the hexadecimal codes and their corresponding variables. Note that the files which are emailed are also considered dynamic content. For example, let’s say that we have siliconchip.com.au January 2010  85 An Example FTP Session . . . The Temperature is currently 26.5 degrees. As mentioned, any files sent by email, such as var0max.txt (on a maximum condition in variable #0), can also contain dynamic content. In order to show the ~ character you need to escape it by using the sequence ~~. For example ~~02 will translate to ~02 yet ~02 will translate to the Subnet Mask (refer to Table 2). The default var0max.txt file contains the following text: The ~1E is currently at ~D0, which is above the set maximum of ~1C! This is an automatically generated message, created on ~E2. Fig.27: an example FTP session. Here a file called “report.pdf” has been been uploaded to the WIB (via the Internet) using the “put” command. List Of Accepted FTP Commands CD: change directory. PWD: show the current directory. DELETE: delete a file. DIR: show the files in the current directory and the file sizes. LS: show only the name of the files in the current directory. PUT: send a file to the ethernet web server. GET: retrieve a file from the WIB. Fig.27 shows an example FTP session. Here the put command is being used to upload a file called report.pdf to the memory card in the WIB via the local network. The first step is to connect to the FTP server and that’s done by going to a command prompt and typing: ftp 192.160.0.34 The WIB’s local IP address has been used here but you would have to substitute the public IP address (or the hostname if you have set up dynamic DNS) if you want to access the WIB via the Internet (as shown in Fig.27). After that, it’s simply a matter of entering the username and password to log on and then issuing the command: put report.pdf a dynamically typed file containing the text: The ~1E is currently ~D0 degrees. From this, it follows that if the name 86  Silicon Chip MGET: retrieve a collection of files from the WIB. MPUT: send a collection of files to the ethernet web server. USER: specify the username for login. PASS: specify the password for login. OPEN: open an FTP connection to a remote server. QUIT: exit the current FTP session. The file should then upload to the WIB. If you get an error that says “Netout: connection reset by peers”, it means that the buffer in the Windows FTP client has overflowed and will have to be increased in size. To do that, quit the current FTP session (using the quit command), then restart it with the command: ftp -w:8192 192.168.0.34 and try uploading the file again. This will double the buffer size from the default. If you get the same error message, double it again by starting the FTP session using the command: ftp -w:16384 192.168.0.34 Similarly, if you want to download a file called report.pdf, use the command: get report.pdf of Variable 0 is set to “Temperature” and the current value for the temperature (derived from a temperature sensor connected to the first ADC input) is 26.5, then this would appear as: As before, ~1E will be replaced by the name of Variable 0, while ~D0 will be replaced by the current value of that variable. ~1C is replaced by the maximum set value, while ~E2 is the current time as determined by the SNTP module. In other words, the email would look like this example: The Temperature is currently at 30.0, which is above the set maximum of 28.0! This is an automatically generated message, created on Fri 28 August 2009 17:00:00. Therefore, by modifying this file and others like it, you can customise the emails that are sent as notifications. Running CGI commands from an HTML form It is possible to execute one of the commands in Table 1 from an HTML form. The commands are of the form: <command>?<name>=<value> Any system setting can then be defined using an HTML form by using the set command (see Table 1 on the SILICON CHIP website), the name of the variable (Table 2) and the new value, eg: set?NTPTimezone=0 will modify the time zone for SNTP to UTC time. An in-depth discussion of HTML forms is beyond the scope of this article but if you are interested you should look at the source code for the supplied website. A number of HTML forms are used to change the WIB’s settings. By imitating these, you can create complex websites. siliconchip.com.au Memory Card Special System Files The are several special system files on the memory card and these either have a “txt” extension or a “dat” extension. For security reasons, these two file extensions should always be set to private in the HTTP Settings (file permissions) – see text. This is the default but you can change this and open up your system to the public if that’s what you really want to do (not recommended!). You can also modify some of the special system files to customise the behaviour of the WIB. The relevant files are as follows: FTP connection, a change in the public IP address detected by the dynamic DNS client, and any email sending activities. log.txt: this file contains a human-readable log of system events since the last reset. It is emailed to the user each time there is a system reset. All important system events are logged, like an incoming test.txt: this file contains the body of the test email sent when the user presses the ‘Test Email’ button in the supplied website. It is used to test that the SMTP settings are correct. The settings.txt file The default settings can be overridden by a file named settings.txt. This file is stored in the root folder of the memory card. In operation, the firmware loads and parses this file at boot-up (or when there is a Master Reset). Each line should contain a statement of the form: <setting name> = <value> where <setting name> is one of the settings in Table 2 (provided it’s not read only), and <value> is the value to set. For example, to change the (default) gateway to 192.168.0.33 you would have a line in settings.txt that reads: Gateway = 192.168.0.33 This would override the default value but not the value that was last set through the web interface. Those values are instead stored in a file called values.dat but in binary form. Note that it is permissible to add any number of spaces before the equals sign for readability. For example, although the IP address settings name is IPAddress, you can validly set the IP Address by writing a line in your settings.txt file that looks like this: IP Address = 192.168.0.30 Restoring the defaults To restore the default values, you can simply delete the file values.dat and reset the WIB by clicking the Master Reset button (or reboot the WIB). siliconchip.com.au settings.txt: this file contains a humanreadable list of single line entries that override the system defaults. The user may modify this file to define new default values. values.dat: this file is used to store system settings in binary form and should not be modified. var0max.txt: this is the file that is emailed when variable #0 has exceeded its set maximum. var0min.txt: this is the file that is emailed when variable #0 is below the set minimum. var1max.txt, var1min.txt, var2max.txt, var2min.txt, var3max.txt, var3min.txt: similar to above but for variables #1, #2 and #3. var0log.txt: this is the file that holds the logged values of variable #0. This file is emailed if periodic logging is enabled for that variable. var1log.txt, var2log.txt, var3log.txt: similar to above but for variables #1, #2 and #3. Correction To Fig.9(b) of WIB Pt.2 ETHERNET PORT MODEM DYNAMIC IP ADDRESS INTERNET FIXED LOCAL IP ADDRESS (EG, 192.168.1.1) 192.168.0.34 WIB (FIXED IP ADDRESS) PC (DYNAMIC IP ADDRESS) MODEM PORT (EG, 192.168.1.2) ETHERNET PORT (LAN) ROUTER ETHERNET PORT (LAN) FIXED LOCAL IP ADDRESS (EG, 192.168.0.1) There isB anSEPARATE error in MODEM the IP addressing & ROUTER shown on Fig.9(b), page 84 of the December 2009 issue. The addressing shown will not work because a router will only forward packets between different networks, eg, from 192.168.0.x to 192.168.1.x on a class C network (and vice versa). This means that we must use IPs for two different networks on either side of the router, eg, use 192.168.1.1 for the Ethernet port on the modem, 192.168.1.2 on the modem port on the router and leave the LAN side of the router at 192.168.0.1 – see above. See also Notes & Errata, p101. Alternatively, you can go to the Basic Settings page of the supplied website and click the Restore Defaults button. Another option if you are creating your own website is to run the defaults command from an HTML file (see Table 1). You can also define the current settings as the defaults by clicking on the Create Defaults button and then resetting the WIB by clicking the Master Reset button (in the supplied default website) or by rebooting the SC WIB (power off and on). January 2010  87