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Using the Status Element to Track Boolean State Variables

Jason -

Most real-world models involve tracking the status of various aspects of a system that are Boolean; that is, always in one of two possible states or conditions (e.g., on/off; yes/no, true/false). For example:

  • If modeling a water supply system, at any point in time, you may need to track whether or not a particular pump is on or off.
  • If modeling a project, at any point in time, you may need to track whether you are above or below a particular spend limit.
    If modeling a complex machine, at any point in time, you may need to know whether or not certain parts of the system have failed, and if so, the manner in which it has failed.


GoldSim provides a powerful element to easily facilitate this - the Status element. Status elements allow you to monitor the status of something that is changed instantaneously (i.e., is triggered) by events. The single output of a Status element is a (True or False). The element has an initial condition (True or False) and two triggers: one that sets the Status to True, and another that sets the Status to False.

The dialog for a Status element looks like this:

Within the Status dialog, you should first specify the Initial Condition for the element (True or False). This can be entered as a condition (e.g., False) or a . By default, it is False. You must then specify the triggering event(s) which cause the element to be set to True and False. These are both defined via Trigger… buttons, which provide access to standard Trigger dialogs.

You would use a Status element to track the status or state of processes or objects in your model. For example, if you were modeling a material handling facility, you could use a Status element to signify whether or not a particular storage area could accept any more (i.e., is it full?). You might then reference the output of the Status element in a Selector element or a Decision element to determine the flow of material in your model.

To understand how a Status element works, consider the following simple example. Assume that a Status element defaults to False. A triggering event is defined which sets the element to True whenever A occurs (every 13 days). Similarly, a triggering event is defined which sets the element to False whenever Timed Event B occurs (every 15 days).

The output of this simulation would look like this (note that in a chart, 1 corresponds to True, and 0 corresponds to False):

Image

This functionality allows you to track the status or state of processes or objects in your model. For example, if you were modeling a material handling facility, you could use a Status element to signify whether or not a particular storage area could accept any more (i.e., is it full?). You might then reference the output of the Status element in a Selector element or a Splitter element to appropriately control the flow of material in your model.

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