creating a batch trip task sequence

Greetings all.

Im having a little trouble with custom tasksequences (I admit mainly because up until now ive been getting away with the standard transport request).

Basically I have a big queue of items and would like to control its dispatch in specific batches/trips (through a table for example). So the table would look something like the global table called "batch table" in the example attached.

Specifically:

- each batch being should be a single trip, that is only travelling to the queue once then out to the various destinations with the various quantities (will involve travel from 1 destination to another)
- Multiple items to a single destination should be possible (simple as it seems this is actually the option that stumped me).

Ive tried modifying the standard tasksequence but haven't had much luck (such as the one that doesn't work in the example). Any help at all would be much appreciated, even if it's just a bit of vague direction as to how to pick up multiple objects and put them at a single location (programmatically not using the queue batching)...

Cheers.

Paul

Hi Paul,

I've taken a look at your model and I have attached a model that might be what you would like to do.

First you have to remember that when the first product enters the queue, the sendto is evaluated immidiately and if the destination is free the "request transport from" is also evaluated directly. In your code you wrote:

treenode item2 = rank(current,2);
treenode item3 = rank(current,3);

But when the first product comes in there is not a "rank(current, 2)" product present so this leads to an error of an invalid tasksequence (as you probably have noticed )

The other thing you have to remember is that a conveyor can only receive 1 item at a time. Only when that item leaves the next product can enter. So in your setup, if you increase the capacity of the operator there will never be send more than 1 product at the same time to the conveyor, the 2nd product will always be send to the next conveyor.

If we look at a possible solution, it is quite complex to use the standard "request transport from" option in combination with the sendto because of the fact that the conveyor only receive 1 product and the "request transport from" trigger is fired for every product that is send on.
So I created a solution be closing the output on entry and create all the necessary tasksequences on the OnEndCollecting trigger. Please take a look and see if you understand what is going on. If not let me know.

Regards,

Steven

Sorry small improvement:

"Only when that item leaves"

should read:

"Only when that item is on the conveyor completely"

Thanks Steven thats really useful (both the application and the concepts behind it).

Just out of curiousity how does one find out about the inner workings of the various objects (eg the sendto being evaulated immediately for the operator for example)? I can't find a lot of this kind of detail documented in the user manual... Is it possible to work out from some code somewhere in the object?

Thanks.

Paul

Paul,

That is a good question

There a few ways:
1. The description of the fixedresource in the "Flexsim Object Library" chapter in the user manual

2. Simply write pt() commands in the triggers and see when they go off

3. Ask on this forum or Flexsim support if you have a specific question

4. If you really want to spend the time, (and have some programming experience) go into the library and check out the functionality of the objects. That cost a lot of time and is usually not necessary but gives you a definitive answer if you need one.

Hope this helps you a bit further.

Regards,

Steven

Hi Steven,

Just to clarify, Im looking at the diagram for how a fixed resource operates (manual> flexsim object library> fixed resource), and it appears on the diagram as if the item is processed before to sendto function is called and the "request transport from" is called directly before the item exits???

Thanks

PS- As a general comment, i find this diagram incredibly useful, and would very much encourage the use of flow diagrams for future help files/ manuals (eg for more of the ojects, showing the various trigger points etc). Personally find it a lot easier to take in than text.

EDIT- Think i can answer my own question- Queues have a zero process time thus sendto and "request transport from" effectively evaluated for each item when they enter