Conveyor pusher

Iam working on a palletizing job. robot needs to pick 5 products and then 2 and then 5 again.
The thing is i am using pusher conveyor for 90 deg turn. We want to see a box waiting on a transfer corner until robot picks up the boxes and push the box after. while picking 5 products no issues. but while picking 2 pusher is pushing parts into picking zona. i need to stop pusher.
Does anyone know how to stop pusher?

Thanks in advance