Programming With User Interfaces; Button Presses - Crestron SIMPL Windows User Manual

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Programming with User Interfaces

Simplified Button-Press
20 • Crestron SIMPL Windows
The heart of any well-designed control system is the user-interface. This is the link
between the end-user and the control system itself. Regardless of how cleverly
programmed, or technically savvy a given system is, if it lacks a quality user-
interface it is unlikely that the system will be appreciated, or used to its full potential.
Crestron control systems offer an impressive array of user interface options, from the
top-of-the-line Isys TPS touchpanels, to cost-effective and simple wired button
panels. No matter what type of interface(s) you are using in your system, this section
will help explain how to use them in your program.

Button Presses

In a program button presses (whether from a touchpanel, wired or wireless button
panel, or other interface) are associated with signals. Since for a given device not all
buttons may be used, unused buttons are not given signal names. When a button is
pressed, the corresponding signal is asserted in the control system program. When
the button is released, that same signal is de-asserted. See the signal-state diagram
below for a graphical representation of this.
Note that in this case the button alone determines the state of the signal. That is,
when the button is pressed, the signal is high, and when the button is not pressed, the
signal is low. Because of this the button is the driving source for that signal. Since a
button can have only two states, high or low, the signal that it drives can only have
two states, thus this signal is a digital signal.
In most cases digital signals are limited to one driving source. That is, it is illegal to
have two different symbols driving the same digital signal. However, there are two
important exceptions to this rule. One concerns the Buffer symbol, which will be
described later. Button presses are another exception, in that a single signal may be
driven from multiple buttons. This can be very convenient, especially in cases where
you want to share functionality across several user interfaces. For example, the same
volume up and volume down controls may be accessible from a touchpanel as well
as from a wireless remote. Instead of having to create different signal names for each
case, and then using an OR symbol to combine the functionality, it is legal (and
desirable) to use the same signal names in both cases.
Crestron SIMPL Windows
Primer – DOC. 6253