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Unfortunately, Sierra secondary APP ports reply to +GCAP with only "OK", and not their APP port number or model number. So instead of using +GCAP, we have to use ATI to get secondary port information. This allows us to detect which port is the APP1 port that we can potentially use for PPP, leaving the primary port available for control and status. Also, some modems have up to 3 or 4 APP secondary ports, which we need to ensure aren't used as primary. The previous check for +GCAP handled that, but let's make it more explicit. AT+GCAP reply: OK ATI reply: Sierra Wireless, Inc. C885 APP1 OK See also: 3f3987e09ee762e48c1d53cb42a1288ce9f332cb (MM_06)
ModemManager. The problem ModemManager tries to solve is to provide a unified high level API for communicating with (mobile broadband) modems. While the basic commands are standardized, the more advanced operations (like signal quality monitoring while connected) varies a lot. Using. ModemManager is a system daemon and is not meant to be used directly from the command line. However, since it provides DBus API, it is possible to use 'dbus-send' command to control it from the terminal. There's an example program (tests/mm-test.py) that demonstrates the basic API usage. Implementation. ModemManager is a DBus system bus activated service (meaning it's started automatically when a request arrives). It is written in C. The devices are queried from udev and automatically updated based on hardware events. There's a GInterface (MMModem) that defines the modem interface and any device specific implementation must implement it. There are two generic MMModem implementations to support the basic operations (one for GSM, one for CDMA,) which are common for all cards. Plugins. Plugins are loaded on startup, and must implement the MMPlugin interface. It consists of a couple of methods which tell the daemon whether the plugin supports a port and to create custom MMModem implementations. It most likely makes sense to derive custom modem implementations from one of the generic classes and just add (or override) operations which are not standard. There's a fully working plugin in the plugins/ directory for Huawei cards that can be used as an example for writing new plugins. Writing new plugins is highly encouraged! API. The API is open for changes, so if you're writing a plugin and need to add or change some public method, feel free to suggest it!