How do I get a sine wave to stop halfway through?

And then re-set it, so the next time it is called it will start from the beginning?

From the manual :

Sine expressions

CyclePosition

Return a value from 0 to 1 representing the progress through the current cycle. For example, exactly half way through a cycle this returns 0.5.

You can use that expression when you're calling it and play around with it at 0.5

Two way to do that, one is as alvarop mentionned, use expressions to get the current CyclePosition and do some action when it reaches >= 0.5

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The other method, is to use Sine with "value only" and use abs() for a one sided cycle.

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First method is easiest, but second method has the best precision (i.e. the Sine value is truly one sided)

Thanks. I was using Value in a similar way to cyclePosition but had a problem in not being able to reset before I made the sine active again.

What i am trying to do is when an object reaches a certain point I want it to activate sine to make it look like it has wobbled on stopping, then stop the sine (ideally after a certain amount of times, but halfway through the cycle is fine, if that's the only way)

What I then want to do is to re start the sine as if it is the first time I have called it, but at the moment its keeping its values so I can't get it to act the way I would like.