Wait signals on conveyor belt

Hello Everyone,
I had doubts on how should i make a conveyor wait till the time the part ahead of it has not been machined yet.
Also, I wanted to ask , I want to perform a small process on the conveyor belt . I tried to implement " work for 20 sec" but that is not working.
For Understanding i have attached a picture with this message.

1)is the place where it waits for 2) to get completed.
At the place 2), i want to perform a small process . How do i implement that as well?
I am open to discussions via zoom as well , if interested.

Thanks

Capture

I’m not sure if this solves your issue, but I wanted to see how this could be done with only Process Modeling.
I added transport nodes that work as intermediate points for the part, and the part moves by interpolating transport between the processes.
Hopefully this layout will work as a good example for you. Note that it requires VC 4.5 to use.
test_layout.vcmx (2.5 MB)

Thanks for the reply. I understood your concept but its not working for me.
Do you mind discussing it online?