How to add a pallet after a few layers

::heading=Context

We have seen cases where the customer wants to create stacked pallets using the palletizer. 

The sequence could go as follows : 

1. An empty pallet is placed on either side of the palletizer. 
2. 3 or 4 layers of boxes are stacked.
3. The program pauses. 
4. The operator places an empty pallet on top of the stack. 
5. The operator validates the task is done by pressing a button, outside of the work zone.
6. Palletizing restarts. The palletizer offsets the release height to compensate for the pallet presence. 

::heading=Knowledge

Here is a template showing how to manage such scenario using the node_rpc_server.setboxdropdistance() script command. 

Line 3 : IF statement makes sure the offset is reset to zero when the pallet is changed. 

Line 21 : Pallet will be placed by the operator after box 72 is placed.

Line 26 : Pallet height is set to 130mm (0.13m). 

Line 28 : Program waits for the operator to press the confirmation button to proceed.