User Manual

Table Of Contents
SARA-R4 series-AT commands manual
UBX-17003787 - R16
19Internet protocol transport layer
Page 223 of 401
19.16.2Syntax
Type Syntax Response Example
Set AT+USODL=<socket> CONNECT AT+USODL=0
CONNECT
Test AT+USODL=? +USODL: (list of supported
<socket>s)
OK
+USODL: (0-6)
OK
19.16.3Defined values
Parameter Type Description
<socket> Number Socket identifier.
SARA-R4 / SARA-N4 - The range goes from 0 to 6.
19.16.4Enhanced Direct Link
The enhanced DL functionality allows the user set up to three kinds of trigger for data transmission:
Timer Trigger
Data Length Trigger
Character Trigger
The triggers can be applied independently to each socket. A socket may be set with more than one trigger.
The trigger must be set after the socket creation and before switching to direct link mode.
By default Timer Trigger and Data Length Trigger are enabled for UDP sockets.
By default no triggers are enabled for TCP sockets.
SARA-R4 / SARA-N4
See the +UDCONF=5, +UDCONF=6, +UDCONF=7 commands description for the transmission triggers
configuration.
19.16.4.1Timer Trigger (TT)
The user can configure a timeout for sending the data. The timer starts every time a character is read from the
serial interface. When the timer expires, buffered data is sent.
The timer range is between 100 and 120000 ms.
SARA-R4 / SARA-N4
The special value 0 (zero) means that the timer is disabled. By default the timer trigger is enabled with a
value of 1000 ms TCP sockets and enabled with a value of 500 ms for UDP sockets.
The +UDCONF=5 command can configure the timer trigger.
19.16.4.2Data Length Trigger (DLT)
The user can configure a maximum buffered data length to reach before sending the data. When this length
is reached the data is sent.
The minimum data length is 3, the maximum data length is 2048 bytes for TCP and 1472 bytes for UDP.
SARA-R4 / SARA-N4
If the data length is set to 0 (zero) the trigger is disabled. By default the data length trigger is disabled for
TCP sockets and set to 1024 for UDP sockets.
If both the timer trigger and the data length trigger are both set to 0, the effective DLT size is 2048 bytes
for TCP sockets and 1472 bytes for UDP sockets.
The +UDCONF=6 command can configure the data length trigger.
19.16.4.3Character Trigger (CT)
The user can configure a character that will trigger the data transmission. When the character is detected the
data (including the trigger character) is sent.
If the specified character is -1, the character trigger is disabled.