How to make the empty cartons stay in the middle loop,
the cartons in stock will go to the sealing machine?
the yellow part is the packaging machine,
there are 12 in total,
the red part is the operator,
and each packaging machine has 2 operators.
The empty cartons will be placed on the conveyor belt in the middle and will not be sent to the sealing machine until they are picked up by the operator and filled with goods.