RS232 Knekt Interface
8
SYSTEM OPERATION
The following sections define the operation of an Intersekt based multi-room Knekt system when
one or more rooms are controlled and monitored via the RS232 port on the Intersekt using its ASCII
command language.
C
OMMAND
S
YNTAX
The Intersekt provides a simple text-based (ASCII) command set to control and monitor the Linn
equipment normally controlled by an RCU. All commands have the following generic format.
Each ASCII command must be contained within [and ] brackets. All characters received “outside”
the brackets are ignored. If access to the on-line help is required (see page 9) a “?” is used as the
first character of the command. Otherwise, with the exception of a few system commands, the first
character of the command must be a digit representing the room number being controlled. The
command and parameter strings can use either upper case or lower case characters, with an optional
“=” character separating the two strings. For example [8VOL50], [8vol50], [8VOL=50] or
[8vol=50] could be used to set the volume level in room 8.
R
ESPONSE
S
YNTAX
The Intersekt returns an upper case ASCII response for each ASCII command received, with the
following generic format.
All responses begin with the “!” character followed by a digit, r, representing the room number
being controlled and generating the response. A status text string, STR, relevant to the received
command may then be return. If the command was not recognised, or if one of its parameters was
out of range, the “?” character is returned as the status text string, to say that the command was not
understood. For example [8VOL=ABC] would return the response !8?<CR>. If the room being
controlled is not available to process the command, the character “B” is returned to say that the
room is busy. If the Intersekt expects the room to acknowledge receipt of the command (see
Command-Response Timing on page 10), and it does not acknowledge, the character “T” is
returned to say that a communication time-out occurred. If the command was a request for status
(see Monitoring Equipment on page 9), the status text string is formatted as the received command.
For example, the command [8VOL=?] would return the response !8VOL=value<CR>, where
“value” represents the current volume level in room 8. All responses are terminated with the ASCII
carriage return character, which not only informs the controlling device that the response is
complete, it also makes the display more readable when a simple ASCII terminal is used to transmit
the commands during the installation and debug process.
[ ? r CMD = PRM ]
Command string
Start of Command
Parameter string
Optional request for help
End of command
Room number
! r STR <CR>
Start of response
Command dependant status text string
Room generating response
End of response