Operator & Process Flow

Question

question

SamCJ asked Apr 24, '19 Andy B commented May 3, '19

Operator & Process Flow

I'm comfortable with Flexscript and I'm using this abstract problem to try to, belatedly, teach myself Process Flow and could do with some guidance.

I have 5 tasks to be completed in series in the order 1, 2, 3, 4, 5. Tasks 1, 2, 4, 5 all take 10 time units and task 3 takes 100 time units. There are 2 operators who can attend any task, and it makes sense to prioritize the downstream tasks . Transport between processes will be undertaken by the Operator who will undertake the process (hence transport, process, free operator) meaning that an operator can be freed up to other tasks when a processing task is complete

In the attached I have a list to store the Tasks, and a series of labels passed from the 3D world into the list: Priority is stage in the process (1 to 5), Entry is time entered the process, Order is a (badly named) counter that counts the number of times a token is replaced on the list and is reset to 0 On Entry to a processor, Start is the 3D object where the flow item is located, Destination is where it is going.

My approach is to have 2 Operator tokens in Process Flow, each checking contents of the list one at a time until some condition in the model changes and one of the List items can be moved to its destination.

I haven't worked out the Pull From List query correctly, but as I seem to be running into more and more problems with this approach and suspect that I have have a logic error rather than a bug to work through. The approach that I have taken results in a significant number of passes through the loop for the waiting tasks, that I'm not comfortable with.

Is there a better way to do this?

I want to adapt this model to remove the transport tasks, so the Operators will be called to the Processors for the processing time only, but can't see an obvious way to achieve this - am I missing something?

Software Version:

FlexSim 19.0.0

process flow

jobshop2.fsm (44.1 KiB)

Answer 1 · 2019-05-02T15:02:50Z

Jeff Nordgren answered May 2, '19 Andy B commented May 3, '19

@SamCJ

Attached is your model with the changes that I've made.

I think I got lost trying to follow your way of doing the model. Wasn't having too much success doing it the way it was done. Then after not doing so well with that, I re-read your request and down at the bottom you state that you really just want the operators there for the process time. So I revamped my whole approach and the attached model is what I came up with.

It will send an operator to the processor that need to be processed with the highest priority (labels on the processors). I started down the road of trying to check if the next processor was available before sending the flowitem on, the way you were similarly doing it. But then I thought, why try and re-invent the wheel. I will just connect the objects like you would normally do. That way, if the next processor is still busy, the sending processor will become blocked and not send the flowitem on. A WHOLE lot easier than trying to account for that situation using PF blocks.

So take a look at the model and see if it is doing what you were needing it to do. Take a look also at the processor Properties to see what was done there. If you have any questions or problems, please let us know.

Oh, one last thing. I use network nodes for the operators to travel on. When you open the model, you will only see one network node by Processor1. If you hold down the "x" key and left mouse click, it will cycle through the display options for the network nodes.

Thanks.

jobshop2-jn4.fsm

jobshop2-jn4.fsm (42.8 KiB)

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