User guide

SATELLINE-3AS NMS / NMS Epic / NMS 869 / VHF
User Guide, Version 1.0
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SL-COMMANDS
Controlling the terminal device (DTE) can instruct the radio modem to make an action. This is
accomplished with the help of the SL commands, which can be used during data transfer in the
Data Transfer Mode . For example, DTE may change the frequency or the output power of
transmitter, or DTE may enquiry current settings from the radio modem.
SL commands must be enabled before they can be used by setting the SL commands parameter
ON in the Programming Mode .
An SL command is a one continuous string of characters, which is separated from other data by
pauses that are at least three (3) characters long. The continuous here means that there are no
pauses between the adjacent characters inside the SL command on the serial line.
No extra characters are allowed at the end of an SL command. The serial interface settings are
the same as in normal data transfer.
The syntax of an SL command is:
S L <Command> <CR> <LF>,
where:
<Command> is the actual character string defining the actual command.
<CR> is Carriage Return (ASCII character 13, 0x0d in hexadecimal)
<LF> is LineFeed character (ASCII character 10, 0x0a in hexadecimal).
Note that the use of <LF> is optional the radio modem does not require it.
If multiple SL commands are sent to the radio modem the next command can be given after
receiving the response ("Ok" or "Error" or the value) of the proceeding command. In addition, it
is recommended to implement a timeout to the terminal software for recovering the case when
no response is received from the radio modem.
The radio modem handles all data strings with the prefix 'SL' as SL commands. Invalid SL
commands are ignored. Note also that the radio modem does not transmit the SL commands.
The radio modem responses using the following format:
<STX>SL<Response Data><ETX><CR><LF>
, where
<STX> Start of Text character (0x02 in hexadecimal)
<Response Data> is a character string, the actual reply to the previous SL command.
The radio modem acknowledges all commands by replying "O
OK"
(command carried out
or accepted) or the requested value, or an "E
ERROR"
(command not carried out or
interpreted as erroneous) message.
<ETX> End of Text character (0x03 in hexadecimal)
The frame characters ease the implementation of parser software for the DTE.
In case the radio modem is receiving a message, entering an SL command to the radio modem
will terminate the reception and the SL command is processed.