Reading ON/OFF from website

Projects Networking, Protocols, and Devices
1

I'm trying to create a system that triggers off reading the text ON or OFF from a webpage, but I'm completely unsure of how to parse the string from the rest of the html gibberish of the page without piping it through another php page to do the filtering to get a clean text response to work with.

The line I am looking for the trigger for is as follows for the on and off states:

<TD bgColor="#A0A0A0" align="center"><strong>Zone State</strong></TD></TR><TR><TD bgColor="#FFFFFF" align="center"><font color = "#F00000">ON </font></TD></TR>

 <TD bgColor="#A0A0A0" align="center"><strong>Zone State</strong></TD></TR><TR><TD bgColor="#009645" align="center"> OFF</TD></TR>

I haven't found any useful example code yet to learn from to figure out how to make use of the network shield for what I'm looking to do. My exact code right now is just the Ethernet WebClient example code with the variables replaced to point it at the web server I want to pull my on/off variable from, I haven't done much from there since I'm not sure how to get the page data into a usable form.

The end-goal of this is that this reading data from a webpage to trigger a L293 to run 24VAC relays to turn on/off 120VAC circuits.

2

I assume that this isn't a website you control, because if it were, you'd make a page with the on/off data that's easier to parse.

Given that, read the returned html line by line into a null terminated buffer and use strstr to look for the text "Zone State". That'll identify the line that has the ON/OFF you're looking for. Then use strstr again to see if you have OFF or ON.

3

Unfortunately I can't control the page, it's part of a controller firmware package that provides a minimal web interface, building a simple php relay page would be the only option there, but I'd rather minimize points of failure and devices involved.