Specifications

Crestron SIMPL Windows Software
Programming with Logic Symbols
Introduction
In the last chapter we saw how a program could be written simply using device
symbols and connecting them via signals. This type of program uses "direct
functionality." That is, button presses (or any other type of system input) are
connected directly to control functions, such as the PLAY command on an IR driver.
When the button is pressed, the PLAY command is sent out the IR port, and it stops
as soon as the button is released. This type of programming is simple, but as control
systems get more complex, you will find that you require more control over what
goes on inside the program. This is handled through the use of logic symbols.
In general terms each logic symbol can be thought of as a very specialized processor.
A logic symbol will evaluate the state of the signals connected to its input terminals,
and generate appropriate signal values onto the signals connected to its output
terminals. The values of the output signals will depend on the nature of the logic
symbol itself, and on the values of the symbol's parameters, where appropriate.
Types of Logic Symbols
Currently there are over one hundred logic symbols available for use by SIMPL
programmers. These symbols range from simple digital logic gates to complex serial
data generators. In order to make it easier to find the symbol or symbols needed for a
particular application, the entire logic symbol collection has been categorized as
follows:
Analog Operations – Symbols that are used to perform analog functions such as
ramping operations for lighting or volume presets.
Conditional – Logic gates that assert their outputs depending on whether some
condition is true or false.
Counters – Binary and decimal counters.
Debugging – Symbols that track signals during run time, or force signals to analog,
digital or serial types.
Device Interface – Mouse and keyboard simulators.
e-Control Software – Symbols that are used by Crestron e-mail power applications.
Memory – Symbols that write and read to NVRAM. That is, they retain data in
memory even if power is shut off.
Primer – DOC. 6253 Crestron SIMPL Windows • 37