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Simulation Interruption
While building your model, there may be times where you wish to stop your simulation at a certain time or when certain events occur. ProModel offers statements that allow you to pause, interrupt, or stop your simulation when necessary.
Pause
The Pause statement pauses the simulation and can also optionally display a message. Using the Pause statement will create a pop-up window during your simulation, potentially with a message if you have defined one. After clicking OK to dismiss the window, your simulation will remain paused and you must press the Play icon to resume your simulation.
To use the Pause statement, use the syntax
Pause “<message>”
where message is the message you would like to display when the simulation is paused. If the message field is left blank, the simulation will pause without displaying a message.
Example
If you include the statement
Pause “Packaging machine reached”
in the Logic for a packing machine Location, the simulation will pause and display the message “Packaging machine reached” every time an Entity enters the packing machine Location.
Prompt
The Prompt statement interrupts the simulation and displays a window that prompts the user for information. The user’s answer will then be assigned to a Variable or an Attribute, and the simulation will continue.
There are two different types of prompt windows that the Prompt statement can create: a text box prompt window and a selection prompt window.
Text Box Prompt
To use the Prompt statement to create a text box prompt window, use the syntax
Prompt “<message>”, <Variable or Attribute>
where message is the message you would like to display in the prompt window and Variable or Attribute is the Variable or Attribute to which the result of the prompt will be assigned.
Example
Defining the statement
Prompt “How long will this customer be eating? (number only, in minutes)”, aEatTime
at a table Location in a restaurant model will pause the simulation to display a pop-up window every time an Entity enters the table Location. The window will display the message “How long will this customer be eating? (number only, in minutes)” and will provide a text box where the user can enter their answer.
The user may press OK to confirm their answer, or press Abort to end the simulation. If the user types “10” into the text box and confirms, then the Attribute aEatTime will be assigned the value 10. The simulation will then resume.
Selection Prompt
To use the Prompt statement to create a prompt window with multiple choices, use the syntax
Prompt “<message>”, <Variable or Attribute>, “<choice 1 name>” : <choice 1 value>, “<choice 2 name>” : <choice 2 value>, “<choice 3 name>” : <choice 3 value> … and so on
You may also use braces to improve the clarity of your code
{Prompt “<message>”, <Variable or Attribute>,
“<choice 1 name>” : <choice 1 value>,
“<choice 2 name>” : <choice 2 value>,
“<choice 3 name>” : <choice 3 value> }
Example
Defining the statement
{Prompt “How long will this customer be eating?”, aEatTime,
“10 minutes” : 10,
“15 minutes” : 15,
“20 minutes” : 20}
at a table Location in a restaurant model will pause the simulation to display a pop-up window every time an Entity enters the table Location. The window will display the message “How long will this customer be eating?” and will provide a list where the user can select “10 minutes”, “15 minutes”, or “20 minutes”.
Once the user has made their selection, they may press OK to confirm or press Abort to end the simulation. If the user selects the “15 minutes” option and confirms, then the attribute aEatTime will be assigned the value 15. The simulation will then resume.
Display
The Display statement allows you to interrupt the simulation to display a message of your choice. In addition to using text in your message, you may also use the names of Attributes or Variables to display their value.
To use the Display statement, use the syntax
Display “<message>”
where message is the message that you would like to display. The names of Attributes or Variables can be included in your message, but they must appear outside of the quotation marks and be separated by commas
Display “<message>”, <Variable or Attribute>, “<message>”
Example
If the statements
vCompleted = 5
aType = 10
Display “The value of vCompleted is ”, vCompleted”, “ and the value of aType is ”, aType
are defined at a Location in your model, the message “The value of vCompleted is 5 and the value of aType is 10” will display on a pop-up window every time an Entity enters that Location.
Stop
The Stop statement allows you to stop the current replication of the simulation and optionally display a message. The simulation will then move on to the next replication of the simulation. If the Stop statement is executed on the final replication of a simulation, the simulation will end. The Stop statement can be used to end a replication once you have received enough statistical data for your purposes.
To use the Stop statement, use the syntax
Stop “<message>”
where message is the message you would like to display when the replication is terminated. If the message field is left blank, no message will be displayed.
Example
Let’s say you wanted to end each replication of a simulation when 100 Entities had been completed in the model. You would first define a Variable with an initial value of 0 to represent the total Entities completed in your model (vCompleted). You would then define the statements
Inc vCompleted
If vCompleted = 100 Then Stop “100 Completed”
in the final Location of your model. Each time an Entity reached the final Location, the value for vCompleted would increase by one. Once the value of vCompleted reached 100, the replication of the simulation would stop, and the message “100 Completed” would be displayed. The simulation would then move on to the next replication.
For more information on the statements used in this example, see the If ... Then Statements and Inc sections of this guide.