3 queue problem

Hi,
PLS, help me to conquer this problem.

MODEL 1: c.f. 3 queue.sfm (attached):
LoGic
transporter1 moves the items to queue3 or queue4 from queue1.
transporter2 moves the items to queue3 or queue4 from queue2.
transporter4 moves the items to queue3 from queue4. This transportation should be done when any item appears in the queue4.

Problem
It doesn't pick up the flowitems in queue4 for transportation when they are available.

MODEL 2: 3 queue-2.fsm

loGic
three transporters (1 , 2 ,3) each from their own queue (1, 2 ,3) transport the flowitems to Queue4 using a dispatcher.

Problem
until the first batch is released in the sink from Queue4, all 3 transporters work together(that's what I like to continue.); however, afterwards, they only focus to transport the blue pallets. why doesn't the old behavior continue?
what should I do to keep 3 transporters to move the pallets?
btw, with or without dispatcher, the behavior appears crazy. at first, all transporters work what they should, but change the behavior when queue batch of Queue4 is complete and released?


thanks in advance!

In model 2 that's because the queue can accept all the items from its first input port and you have no pull strategy specified .


You can add a pick-up queue of size 1 at the queues which I think will give you the bahaviour you want. So the connection would be queue3->Queue3_pickup->Queue4 and similar for the other two. Then make the transport pick up from there.

Alternatively put a pull rule on the Queue4

Originally Posted by Jason Lightfoot

In model 2 that's because the queue can accept all the items from its first input port and you have no pull strategy specified .


You can add a pick-up queue of size 1 at the queues which I think will give you the bahaviour you want. So the connection would be queue3->Queue3_pickup->Queue4 and similar for the other two. Then make the transport pick up from there.

Alternatively put a pull rule on the Queue4

Thanks,
you are right in the second model.I don't understand why in-between-queue with maxcontent 1 works? and also why it assigns randomly the corresponding transporter to do the job. at each releasing batch, the correspondent transporter (say,1) goes to the next queue (say,2). crazy enough.

And I don't see ur point for doing some kind of pulling.

Again Thanks Jason,
Check my words for yourself! c.f. attachment

A queue doesn't have any processing time so all items are released as soon as they enter (providing they're not batching). That means they evaluate their 'send-to' conditions for all the items immediately - it's not done one at a time as they leave, it's done until the downstream capacity is fully allocated. This timing discrepancy is I think the thing that is causing your confusion. By adding a single capacity queue you force the allocation to be done on a one by one basis.

As for the allocation of the transporter, you can choose on the dispatcher which one gets the task in the pass-To pick option. One option is to allocate the nearest free transporter.