RS-232 Serial Port Protocol
Sound play-out may also be controlled via commands received via the serial port. The data format is the
current baud rate (default is 2400 baud), 8 data bits, 1 stop bit and no flow control.
Sounds may be started, queued and stopped using a simple ASCII protocol. The SOH/ETX protocol
starts each command with a single ASCII Start of Header control character = 01
16
or
CTRL-A
, represented
herein as
<SOH>
and ends each command with a single ASCII End of Text control character = 03
16
or
CTRL-C
, represented herein as
<ETX>
.
The actual command is determined by the next lower-case ASCII character following the
<SOH>
:
Command character:
Commands to:
p
Play or queue sounds
v
Control volume
a
Control amplifier
l
Control line input
The command character is followed by a single character command modifier that is command specific.
Command
Command modifier:
Modifies command to:
p
+
Start Sound
v
Increase Volume
a
Un-Mute Amplifier
l
Enable Line Input
p
-
Stop Sound
v
Decrease Volume
a
Mute Amplifier
l
Disable Line Input
p
&
Queue sound
~
Flush queue
!
Stop sound and flush queue
v
=
Set Volume Remembered
<
Fade Volume Down
>
Fade Volume UP
^
Set Temporary Volume
The command modifier for some commands is followed by a data argument that is sent as ASCII Hex
strings two characters in length.
In the SOH/ETX command descriptions that follow there are spaces shown between the different parts of
each command.
THE EMBEDDED SPACES IN THE FOLLOWING DESCRIPTIONS ARE FOR CLARITY ONLY,
ARE NOT PART OF THE TRANSMITTED / RECEIVED COMMANDS AND SHOULD NOT BE
INCLUDED !
