Send message from a queue when it is empty

Hi all,

When a batch of 25 comes into a queue, an operator will carry the items one by one to a sink. What I would like to do is when the queue has reached 0 content, it will send a message to the other object in the model. But how?

I know that OnExit trigger cannot be used because when every time an item is moved out of the queue, it will trigger the function.

So, can someone please help?

Thank you

Hendry

Hendry,

you will have to check the content of the Queue in a condition for sending the message:

if (content(current) == 1)
senddelayedmessage(receiving object, delay, current, 1);

Notice, that you will have to check the content against "1" instead of "0", because that will fire when the last item exits the Queue.

Good Luck

Ralf
FlexSim

Hi Ralf,

Thank for your reply!

Your coding is pretty easy to understand and it works!!!!!

For my knowledge, but may I know why we use senddelayedmessage instead of sendmessage. If I put the delay time is 0, would these two terms become the same?

Thank you!!

Hendry

Hendry,

there is a very extensive examination of the differences in the user manual.
Please look it up in there for further explanation. The short answer is:

Sendmessage() is executed immediately when called and jumps back into the code of the calling function after execution, while senddelayedmessage() with a delay of zero time adds an event to the event list in zero time.
This means code following the senddelayedmessage() command will be executed before the message is sent.

Good Luck

Ralf
FlexSim

Hi Ralf

Can you please teach me on how to send a message to multiple objects at the same time when the content of my queue reaches 0? I tried using "&&" to send message to two objects. e.g.

if (content(current) == 1)
senddelayedmessage(object1&&object2, delay, current, 1);

Well, it is not working..
Really many thanks to you if you can guide me again!

Hendry

if (content(current) == 1)
{
senddelayedmessage(object1, delay, current, 1);
senddelayedmessage(object2, delay, current, 1);
}

There is a help section "Writing Logic in FlexSim" in the User Manual under "Help" which I strongly recommend for you to read.

Good Luck

Ralf
FlexSim

Hi Hendry,

Another way to send messages to multiple objects is by looping through all the queue's connected to object's outputs(Source).In this example source feeds two queues and i close input on reset on each queue .If the content of any queue reaches empty i fill up the queue by opening its input port and again closing input on message.I put this code on creation trigger.

 /**Custom Code*/
  treenodeitem = parnode(1);
  treenodecurrent = ownerobject(c);
  int rownumber = parval(2);  //row number of the schedule/sequence table
//loop through all the queue's connected to object's outputs
  for (int i=1; i<=nrop(current); i++) {
         treenode queue = outobject(current, i);
  //if the queue is empty...
         if (!content(queue)) {
  //open the queue's inputs
  openinput(queue);
  //and send a delayed message that will close the queue's inputs again
  senddelayedmessage(queue,1,current);
         }
  }

Hi Ralf and Sagar,

Really many thanks to both of you for the detailed steps and useful information. It does help improving my model. Thank you so much!

Hendry