Global variables to control state of a machine

Hi everyone,
In my model I am trying to use global variables in order to control a machine.
In brief - there is a machine and a queue. The queue has certain capacity. When the capacity is lower (or equal) than certain value (e.g. low_value) the machine starts filling up the queue. When the queue reaches upper value (e.g. high_value) the machine stops feeding the queue.
Every time when the machine starts there is setup time.
I tried to use two variables but I can't make it working.
If someone has an idea that would be very much appreciated.

Thanks in advance,
Mike

Mike,

First I thought it is a very easy task, but it was getting interesting because of the setup. So it is easy and not very easy.

I built a small model to solve it.
Main idea is to control the Processor with the Queue depending on the content (Queue OnEntry OnExit). For LowLevel and HightLevel I use labels to easily adjust them.
The Processor has a label for the SetupTime and a label FlagSetup. This label is used to indicate if there is a setup or not. If flag is set the SetupTime is used otherwise the SetupTime is zero.
Processor has code in Setup Time and OnReset.
Interesting was also that the second arriving item will get setup, because the condition content <= LowLevel is true. To prevent this there is an if-statement to check if the first item leaves the Queue.

I hope everything is understandable, because I put some comments into the code.

I probably would try it with open and close the input port of the processor in equal to the filling of your queue. This would be done with:

In the queues triggers.

ONEntry Trigger
if(content(current)>250)
{
closeinput(current);
}

ONExit Trigger
if(content(current)<30)
{
openinput(current);
}


Instead of "current" you can use your global variables or even conect the queue and processor via centerport and use "centerobject".
Now you only have to look, how to implement the setup.

Greetings

Thanks for your solution, Tom. It's very elegant.
I was like you - thought it's easy but it's not. Well, at least to me.
From what I see you don't use any global variables. Just labels. Am I correct?
I have noticed when I increase SetupTime to (for example) 50 every part gets setup. I am not sure where it is coming from.

Mike

You are right, that I just using labels. You could also use Global Variables. It is just information and in my eyes it makes not differences if the information is on a label or Global Variable (or Global Table). Just change it the way you like to have it.

If you increase the SetupTime to (e.g.) 50 every part gets setup, because the condition in the OnExit Trigger of the Queue is always true (if(content(current) <= getlabelnum(current,"LowLevel"))), because the Queue will not fill up because of the long setup time and stay under the LowLevel.
You need additional information, if you want to prevent this. The question is what will be the rule for doing setup? If this information is available, I am pretty sure it can be implemented.
In the moment the model solves the task you described in your first post. So you need to be more precise to solve your second task.

Thank you for your reply, Tom.
I was just experimenting with the first model and was curious why it was happening. I understand now