converting text to binary code

I have a text field(name=convertStr) in which you enter some text then click the submit button. If thens parses the variable $convertStr to the new script below: <?php $curVersion = ".001"; $binStr = pack ("A", "$convertStr"); $normStr = unpack ("A", $binStr); echo ("normal string = $convertStr<br>\n"); echo ("binary string = $binStr<br>\n"); echo ("unpacked binary = "normStr[A]<br>\n"); ?> All I want it to do is take $convertStr convert it to binary code and set the value to $binStr, the decode $binStr back in to text format as $normStr. I don't know what method to use. It isn't explained very well at all on php.net manaual. can anybody help me?? thanks Scott.