Time visitors visits

[Wonga]

I have set up a visitors account on my forum so guests can sign in and view before registering an account.

Question

Is there any code that can time how long the visitor is logged on for and then after a set period of time automatically log them out and send them to the registration page?

Thanks.. 

[IchBin]

Probably something you should ask at SMF. Please read the stickies in the boards. This board is not for support. Its for block code snippets.