Using the NetPorter DAQ

The NetPorter DAQ is especially well-suited to work with NetPorter software. Let's look at a simple example that has the board controlling a Web page. The NetPorterDAQ has 5 analog inputs, but the page only shows the first one. The Web page does some numeric processing using JavaScript and also shows LEDs for digital input:

You can download the files that make up this example.

Here is the important part of the properties file:

defaultuser=xlw
defaultpassword=bnetpdemo
defaulthost=netporter.al-williams.com
defaultdirectory=c:/user/awce/netporter/daq/files
defaultftpdir=public_html
defaulttemplatedir=c:/user/awce/netporter/daq/templates
smtp=smtp.al-williams.com
fromaddress=netporter@al-williams.com
rules=c:/user/awce/netporter/daq/rules.txt
stimulus=c:/user/awce/NetPorter/daq/stim.txt
port=COM1
baudrate=19200
bits=8
stopbits=1
parity=0
flow=1

This is pretty standard. Just 19,200 baud on COM 1 with RTS/CTS handshaking. The stim file, is empty and just a place holder, by the way.

The rules.txt file looks like this:

MATCH (.+)=(.+)
SET $1=$2
BUILD daq.template
SAVE daq.htm

That's it. NetPorter DAQ is set to output data periodically and the format is exactly what NetPorter wants.

Now the template that forms the Web page:

<HTML>
<HEAD><TITLE>Netporter Data Acquisition</TITLE>
<META HTTP-EQUIV=REFRESH CONTENT=15>
<SCRIPT>
<!--
function convert(ct)  // function converts raw counts to voltage
{
  var v;
  v=ct*5/1023;
// round to 2 places
  v=Math.floor((v+.005)*100)/100
  return v;
}
//-->
</SCRIPT>
</HEAD>
<BODY BGCOLOR=cornsilk>
<h1>Analog Data</h1>
Voltage on A0=
<SCRIPT>
<!--
document.write(convert(<VAR A0>));  // note NETPORTER variable
// of course you could loop and do them all :-)
//-->
</SCRIPT>
 Volts (RAW = <VAR A0>) <!-- another NETPORTER variable -->
<HR>
<H1>Digital Inputs</h1>
<TABLE BORDER=0 BGCOLOR=#F5E5E8>
<TR>
<SCRIPT>
<!--
 byte=<VAR D0>;  // Read the NETPORTER input

// this loop picks a lit or dark LED for each bit
 for (mask=0x80;mask!=0;mask=mask>>1)
  {
  if ((byte & mask)==0) led="ledoff.gif"; else led="ledon.gif";
  document.write("<TD><IMG SRC='" + led + "'></TD>");
  }
//-->
</SCRIPT>
</TR></TABLE>
</BODY>
</HTML>

That's it! You can view the page at your server address port 808 (unless you changed the properties file to use another value). So on your local machine, you'd view http://localhost:808/daq.htm, for example.

A few important notes:

	The page refreshes every 15 seconds thanks to the META tag near the top of the file.
	There are two spots where NetPorter writes a variable inside JavaScript. This allows you to send NetPorter variables to JavaScript routines. Document.write allows JavaScript to send data to the user's browser screen.
	The raw count is also shown using a NetPorter variable, but this time in normal HTML