Tyco Electronics 1525l Car Video System User Manual


 
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SECTION 3. COMMANDS
This section describes all of the commands that can be used with the MagTek Windows Device
Drivers. Some commands require parameters to indicate to the driver exactly what function is to
be performed. While there are a few device-specific commands, most commands can be used
with any device.
DATA FORMAT
All commands sent to the driver and all responses received are strings of printable ASCII
characters delimited by <LF>. The driver will also accept <CR> as a delimiter. All command
and response strings begin with the character
/. If a command has arguments, they should be
separated with one or more white spaces. The driver accepts space
<SP> and <TAB> as white
space characters.
Note
A command delimiter sent immediately after the previous
command delimiter is interpreted as an empty command and is
ignored by the driver.
RESPONSES
All responses to the transaction commands are formatted with fixed fields, to allow them to be
parsed either by scanning for white spaces or by using constant offsets into the response string.
In the descriptions of the commands found later in this section, the arguments sent with the
responses are shown in their respective locations but may not indicate the exact number of
spaces. The actual responses are sent in a fixed-field format, as shown in the following table:
Field Offset Size Comment
command name 0
(0-11)
12 This field identifies the command that produced this
response, e.g.,
/get is followed by 8 spaces to fill
the 12 locations.
arg1 12
(12-23)
12 Fixed-size argument – value depends on the
command sent. A property name is left justified in
the field and begins in location 12. Status
information is right justified in the field (with a
trailing space) so the SS value will always be located
at positions 21 and 22.
arg2 24
(24-??)
var Variable size argument – used for responses with
variable-size data, like
/get prop or read status
data.