Thanks, I'll give that a try, but I need to capture the value of the
variable every second not just when its changed. That way I can plot
the duration the variable stays at any value, onto the graph. I need
to start a timer when the user starts the process and then capture the
variables value each second until the user stops.

Not sure how to stop the capturing of the variable either as I would
know how many seconds he process will run?


Thanks,
Matt.