Store variable data to file on change event

Store variable data to file on change event

I'm not sure if this is possible but what I would like to be able to do is, as the title suggests, store a variable value as it changes.
I would like to end up with a file like this:
$variableName, #value, TIME
$variableName, #value, TIME
$variableName, #value, TIME
$variableName, #value, TIME
Is this possible? Would it involve the user of alarms? So many questions!
thanks,
mat

This is a migrated post! Originally posted on 25.09.2008 by user matholton. Please be aware that information can be outdated.