User's Manual

SARA-G3 and SARA-U2 series - System Integration Manual

UBX-13000995 - R18 Advance Information System description

Page 55 of 206

1.9.1.5 Multiplexer protocol (3GPP TS 27.010)

SARA-G3 and SARA-U2 series modules have a software layer with MUX functionality, the 3GPP TS 27.010

Multiplexer Protocol [13], available on the UART physical link. The auxiliary UART, the USB and the DDC (I

serial interfaces do not support the multiplexer protocol.

This is a data link protocol (layer 2 of OSI model) which uses HDLC-like framing and operates between the

module (DCE) and the application processor (DTE) and allows a number of simultaneous sessions over the used

physical link (UART or SPI): the user can concurrently use AT command interface on one MUX channel and

Packet-Switched / Circuit-Switched Data communication on another multiplexer channel. Each session consists of

a stream of bytes transferring various kinds of data such as SMS, CBS, PSD, GNSS, AT commands in general. This

permits, for example, SMS to be transferred to the DTE when a data connection is in progress.

The following virtual channels are defined:

x Channel 0: control channel

x Channel 1: AT and data

x Channel 2: AT and data

x Channel 3: AT and data (not available on SARA-G300 / SARA-G310 modules)

x Channel 4: AT and data (not available on SARA-G300 / SARA-G310 modules)

x Channel 5: AT and data (not available on SARA-G300 / SARA-G310 modules)

x Channel 6: GNSS tunneling (not available on SARA-G300 / SARA-G310 modules)

x Channel 7: SIM Access Profile (not available on SARA-G3 series modules)

For more details, see the Mux implementation Application Note [26].