Overview
~~~~~~~~
sierracns is a simple tool for checking Sierra 3G modem connection status
and signal strength while PPP session is active.

It was written for MC5725 (AC595U) mini-PCI-e CDMA card, but may also work
with MC7xxx, MC8xxx and other Sierra GSM/UMTS/WCDMA cards.

sierracns is a limited CLI equivalent of Windows-only Sierra Wireless Watcher.


Building
~~~~~~~~
Run make.
Make sure relevant character device (/dev/ttyUSB1) is writable.
There are no dependencies other that basic libc.


What is CnS
~~~~~~~~~~~
Sierra Wireless 3G modems handled by sierra.ko kernel driver provide three
TTY devices, typically named ttyUSB0, ttyUSB1 and ttyUSB2.
The 1st port (ttyUSB0) provides Hayes modem interface and PPP.
The 3rd port (ttyUSB2) is GPS NMEA output.

Sierra Control and Status protocol, or CnS for short, is a proprietary protocol
these modems talk on their 2nd tty interface. 

CnS allows querying runtime status data from the modem without interrupting
PPP connection on the 1st port, as well as doing some configuration
like setting modem internal time, managing phonebook on GSM units and so on.

The 2nd port is also used to re-flash modem firmware in newer modems,
but that does not involve CnS strictly speaking.


Tool status
~~~~~~~~~~~
The tool is highly experimental.
Be ready to tweak it for your particular modem.

Complete CnS protocol documentation is not available publicly.
There are several versions with serious compatibility issues between them,
and no clear way to tell which one is being used.

Of particular importance is the difference between older CDMA/EV-DO and newer
GSM/UMTS/WCDMA modems, as they may reply with wildly different data to the
same requests. Bogus output from sierracns should not come as a surprise.


Author
~~~~~~
Alex Suykov <alex.suykov@gmail.com>
Patches, suggestions and reports on specific modems are welcome.

Please note I am not affiliated with Sierra Wireless in any way
and do not have access to any restricted documentation.