RS232 Knekt Interface
9
E
NABLING
ASCII C
OMMAND
M
ODE
The ASCII command mode is enabled when the Intersekt receives the command
<CR><LF>[REMOTE]<CR><LF>. The first <CR><LF> character sequence ensures that the
receive buffer within the Intersekt does not contain spurious characters, while the second terminates
the command. To return from the ASCII command mode, the Intersekt must be reset by removing
power.
C
ONTROLLING
E
QUIPMENT
Before a device can be controlled, its ASCII command set must be selected. Each room selects the
command set of both an “amplifier” device and a “source” device. The “amplifier” device is
selected using the [rAMP=p] system command. For example, [8AMP=LNRCV] selects the Knekt
line receiver as the “amplifier” device for room 8. The “source” device is selected using the
[rSRC=p] system command. For example, [8SRC=KARIK] selects the Karik CD player as the
“source” device for room 8. The selected devices can then be controlled when commands from their
respective ASCII command tables are received. For example, the command [8MODE=PAUSE]
would pause the CD, and [8VOL50] would set the volume level. Any commands received for an
“amplifier” or “source” device not currently selected will result in the “!r?<CR>” response being
returned, to say that the command was not understood.
M
ONITORING
E
QUIPMENT
To minimises both the RS232 communications between the Intersekt and the controlling device,
and the communications between the Intersekt and the Linn equipment being controlled, a two stage
monitoring system has been implemented.
The current “amplifier” or “source” device status is read into data buffers within the Intersekt when
the system commands [rSTAT=AMP] or [rSTAT=SRC] are received, or when a command which
automatically reads the current device status is received. The response from these commands are
delayed due to the time required to initiate and complete the communication between the Intersekt
and the device being monitored (see Command-Response Timing on page 10).
The “amplifier” and “source” device ASCII commands that provide a “?” parameter are defined as
specific status commands, and return the current state of the parameter they are monitoring. Rather
than reading the device status directly, the information returned is based on the contents of the
Intersekt data buffers. Since these commands do not require communication between the Intersekt
and the device being monitored, the response is returned immediately.
For example, if the Kairn is the selected “amplifier” device for room 1, issuing the command
[1STAT=AMP] would read the current amplifier status into the Intersekt data buffer. The volume
and balance levels, and the selected listen input, could then be returned by issuing the [1VOL?],
[1BAL?] and [1LIS?] specific status commands in sequence.
O
N
-
LINE
H
ELP
Instead of returning some form of help when a command is not understood, the on-line “help text”
responses are only returned when an explicit request for help is made. This prevents unexpected
responses, possibly containing a large number of characters, being returned while the user is running
application code to control devices.
When the [?] command is received, the top level of help text is returned. Further requests for help
are made by preceding any of the listed commands with a question mark. For example, if the Karik
