The Controller building block indicates when a particular device is attached.
A Controller building block has no inputs and one ON/OFF output. When the device is attached, the output turns ON. When the device is not attached, the output turns OFF.
Preconfigured Controller building blocks can be found in the center section of the Palette window by selecting "Controllers" from the popup menu, then selecting the desired device. Unconfigured Controller building blocks can be created by right-clicking on a Page, then selecting Create Building Block ‣ Device ‣ Controller.
The device that the Controller building block responds to is shown in the Identity tab of the Inspector window. To assign a different device, drag a building block for the new device from the Palette window into the Inspector window. The Inspector window will copy the device settings of the dropped item.
If multiple identical devices are attached, the Controller building block can be configured to turn its output on when any device of that type is attached, or only when the first, second, third, or fourth device is attached.
In the example to the right, the block will turn its output ON if any X-keys XK-24 is attached.