# The Graphical Input Device

The Graphical Input Device enables model users to: (1) see, at a glance, the shape of a graphical function, (2) edit a graphical function from the Interface level; (3) restore a graphical function to its author defined relationships; and (4) animate graphical functions during a simulation.

Important to note:

- You are allowed only one Graphical Input Device per graphical function; once you've assigned a graphical function to a Graphical Input device, you can't assign it to a second one.

Basic Operations: Click once to select a Graphical Input Device from the Tool Bar on the Interface level. Click once again to deposit it. An unassigned Graphical Input Device looks like the one shown in Figure 6-23.

Figure 6-23 Unassigned Graphical Input Device

Double-click on the face of the device to enter its Define dialog, shown in Figure 6-24.

Figure 6-24 Graphical Input Device Define Dialog

The dialog will contain a scrollable list of all graphical functions in the model. Double-click on any graphical function in the Allowable list to move it into the Selected Box. Alternately, select and click >> button to make the transfer from Allowable to Selected. A click on the << button will move the variable out of the Selected box.

If you select an arrayed graphical function, what happens next depends on whether or not Apply to All has been selected in the graphical function. If you select an arrayed graphical function where Apply to All has been turned off, you will be given the opportunity to select the element of the graphical function that the Graphical Input Device will control. If you select an arrayed graphical function where Apply to All has been turned on, the resulting graphical input device will control all elements of the graphical function.

Once a graphical function has been associated with the Graphical Input Device, a click on OK will give you what you see in Figure 6-25.

Figure 6-25 Defined Graphical Input Device

If you double-click a Graphical Input Device that has a graphical function associated with it, the dialog associated with that graphical function will open. You'll then have the ability to edit the graphical function. However, you are not really editing the existing graphical function relationship. That relationship is being preserved! When you OK the dialog, the Graphical Input Device will display a Restore button as illustrated in Figure 6-25.

A click on the Restore button will cause the graphical function that exists in the diagram-level variable (the one that was being preserved while you did your editing) to be restored. If you wish to edit the actual graphical function relationship, you must do so by entering the graphical function dialog on the model diagram. This feature enables end-users to preserve the original relationships for subsequent restoration, while exploring alternative relationships during a scenario analysis.

Note: Editing and Restoring of the Graphical Input Device can occur only when the model simulation is stopped. When the model is running or paused, the Graphical Input Device cannot be opened, and its Restore button will be inactive.

Animating the Graphical Input Device: Once you've associated a graphical function with a Graphical Input Device, when you run the model, you will see the position of the "Y" value of the graphical function (as it varies over the course of the simulation) indicated by an arrow-pointer. An example of what you'll see is shown in Figure 6-26.

Figure 6-26 Animated Graphical Input Device

The animation capability makes the Graphical Input Device a hybrid input and output device. Not only is animation useful for end-users who are trying to gain an understanding of what's going on during a simulation, it is also helpful when you are de-bugging your models. It enables you to see at a glance which of the graphical function relationships in your model are operating "within bounds," and which are slamming into and out of bounds "instantly."

Re-assigning a Graphical Input Device: To re-assign a Graphical Input Device, double-click on the Graphical Input device you wish to re-assign. When you do, the associated graphical function dialog will appear. In the resulting graphical function dialog, click the Delete Graph button. Doing so will have no impact on the original graphical function associated with the diagram-level variable. It simply will disassociate the Graphical Input Device from the particular graphical function to which it is tied. You then are free to re-assign the Graphical Input Device to any other graphical function that has not yet been assigned (or if you no longer want the device, you can Dynamite it).