Buffer Example: Multi-Device Control - Crestron SIMPL Windows User Manual

Software
BUFFER Symbol- High/Low
42 • Crestron SIMPL Windows
This symbol differs from the other symbols discussed to this point in that not only
does it allows an arbitrary number of inputs (in addition to the enable), but each
input has a corresponding output. This is unlike the NOT, OR, and AND symbols,
which have just a single output. Realize that the each input/output pair in the Buffer
is independent of the other input/output pairs. That is, a given input signal can affect
the state of its corresponding output (when the symbol is enabled), but will not affect
any other output. It is because of this that the Buffer is sometimes referred to a
compound AND symbol, where each input it AND-ed with the enable input to
determine the state of each output.
One interesting and very useful property of the Buffer symbol is the nature of its
output signals. Previously we described digital signals and cautioned that each digital
signal could have only one driving source, though there were some exceptions to this
'rule.' We also learned that system inputs like button presses were one such
exception. Outputs of the Buffer symbol are another exception. This means that a
signal being driven by a Buffer may also be driven by another Buffer, or by a button
press (or other system input). This characteristic has far-reaching consequences that
will be discussed in detail later in this manual.

Buffer Example: multi-device control

A common application for the Buffer symbol is to allow control of many devices
using a shared set of buttons. This is useful when programming hand-held remote
transmitters, which have a limited set of buttons. A typical layout for such a remote
is to have one set of transport buttons, with different source select buttons to
determine which device the transport buttons will control.
Because a Buffer works like a compound AND symbol, we often need to generate
'state' signals. That is, signals whose value denotes the state of something in the
system. In this example we will need signals for each source which tell us whether
that source is currently selected or not. In the following chapter we will see how to
generate these signals, but for now, we will simply assume that we have them. See
the sample program.
Crestron SIMPL Windows
Primer – DOC. 6253