Write a new value to VW through a web page

I work with a s7-200 PLC CPU 224, Now I have a program downloaded in my PLC. I want to read and write to VW28 via a web page. Reading goes well with JavaScript and CGI but when I want to write a new value to VW28 it doesn’t work. Is there someone who has an idea how to go about the reading part? This is what I got so far:

Read: this reads the Variable Word: called Var0 and Var1

<script language="JavaScript">
<!--
var Interv = 5

function startClock() {
Interv = Interv - 1

var now = new Date()
var dummystr = parseInt(now.getTime() / 1000)
delete now

if (Interv < 0) {
document.ICUGTW.setNoVariables(2);
document.ICUGTW.setVariableName(0, "Var0");
document.ICUGTW.read();
document.myform.varWord0.value = document.ICUGTW.getValue(0);
document.ICUGTW.setVariableName(0, "Var1");
document.ICUGTW.read();
document.myform.varWord1.value = document.ICUGTW.getValue(0);
Interv = 5
} else {
document.myform.time.value = Interv;
}
timrID = setTimeout("startClock()", 1000)
}
// -->
</script>

To write to a bit in the PLC called Var2: This works

document.ICUGTW.writeVariable('Var2', '1'): // bit on
document.ICUGTW.writeVariable('Var2', '0'); // bit off

But how do I write a new value to Variable Word 28, VW28 = Var3
When I use the line below the value of Var3 (VW28 in the PLC) becomes 0

document.ICUGTW.writeVariable('Var3', '0');

When I use the line below the value of Var3 (VW28 in the PLC) becomes 256

document.ICUGTW.writeVariable('Var3', '1'):

Is there someone who has done this before? Thanks for reading my post.
Aafke

Looks like your setting the upper byte of the word
to one and not the lower byte i.e.

00000001 00000000 = 256

Make sure the variable your looking at is correctly addressed
when writing/reading back the data, with relevant byte ordering.

I'm not familier with the Siemens script functions writeVariable
etc, however I used to get similar problems with other packages
in the way they write to the byte order of the word.

DES