Can I set inport 1 of a combiner is "pull" while inport 2 is push?

Hi,

As title, I would like to use a combiner to simulate a loading bay.

For the combiner port 1, a flowitem truck acts as a container and the truck is pulled by the loading bay request. While port 2 is the finished goods and are pushed by the production line.

I think the natural behavior of the combiner will work for what you want to do. A combiner first opens input port #1 and waits for a flowitem to enter through it. Once the flowitem enters, the combiner opens input ports 2 and higher and waits for flowitems to enter according to the quantities listed in the Components List table of the combiner for each of the input ports respectively. You can use the OnEntry trigger to update the Components List table requirements based on the truck that enters port 1. You can also use the Pull Requirement to filter which flowitem within the upstream ports gets to come in based on labels of the flowitem and/or the input port number currently being considered (because the Pull Requirement passes in a reference to the port).

Thanks Cliff, my real problem should be at how to pull alone a set of flownodes (use of flownodes to simulate the truck(flowitem) to the loading bay (combiner) ).

In the model attached, since the loading bay have space only enough for 1 truck, so only if the combiner have no truck, the source will create a truck.

There are two problems:
1. The 2nd truck never shows up even the 1st truck is left (I click re-evaluate pull requirement/ downsteam availability already)
2. The pull requirement still not good as if the flownodes path is very long, every flownode should check all downsteam nodes content = 0 to pull??

Regards,
Kelvin

problem soloved by using global varible as shown