SL869 SW User Guide
1VV0301002 Rev.6 – 2013-10-1
Reproduction forbidden without written authorization from Telit Communications S.p.A.- All Rights Reserved.
Page 10 of 25
Mod. 0806 2011-07 Rev.2
Packet Length
The NMEA standard specifies a maximum number of characters for each data packet, but the
SL869 does not strictly adhere to this limit.
2.3.
Commands
Commands are sent from the Host Processor to the SL869 and have the basic structure
illustrated below:
command-ID[,parameter1,parameter2,…,parameterN]<cr><lf>
Parameters, if present, are delimited by “,” characters as per the NMEA protocol. All SL869
commands are proprietary and therefore all command-ID’s begin with the “$PSTM” character
sequence.
In most cases, the SL869 will echo the command back out to the Host Processor after the
command has been executed. Commands that are not echoed are indicated in the detailed
commands descriptions later in this Guide.
NOTE:
An easy way to send commands to the SL869 manually is to write the command to a text
file and use the “send text file” function of the terminal emulator. When doing so, make
sure that the <cr><lf> characters are transmitted at the end of the command.
2.4.
Messages
Messages are sent from the SL869 to the Host Processor and have the basic structure
illustrated below:
message-ID,<data1,data2,…,dataN>*<checksum><cr><lf>
Individual data fields are delimited by “,” characters. The checksum is provided for purposes
of bit error detection by the Host if desired.
The SL869 outputs certain standard messages as defined in version 3.01 of the NMEA-0183
protocol standard. The message-ID for standard messages begins with an NMEA talker ID:
“$GP” indicating GPS, “$GL” indicating GLONASS, and “$GN” indicating global
navigation. Specific talker IDs used for each message are described later in this Guide in the
Messages section.
The SL869 also outputs proprietary messages. As with commands, proprietary message-IDs
begin with “$PSTM.” Note that some proprietary messages are responses to input commands.
