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I am interested in using the SIM7600 module for designing a system with LTE communication. The module will be connected to the host system via USB.

I would like the host system's Linux to use PPP to connect to the internet via the module and to be able to send/receive SMS at the same time. So, I will need at least 2 USB virtual ports for these two capabilities. I've seen in the hardware design document that 4 virtual ports are available: audio, AT, diagnostics and NMEA. I guess the AT port will be used for the PPP connection.

So, are there other virtual ports (different from the 4 above) I can use for SMS AT commands, or can I use one of the remaining 3?

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  • \$\begingroup\$ question: if you're using a linux host, and USB, why not simply use one of the many "LTE sticks" that you can buy for cheap? \$\endgroup\$ Aug 21, 2020 at 16:56
  • \$\begingroup\$ @MarcusMuller The system will use a module. A LTE stick cannot be used in this design. \$\endgroup\$
    – Cristian M
    Aug 21, 2020 at 17:08
  • \$\begingroup\$ sorry, I didn't mean the full stick including the PCB it's on, the USB connector and the plastic case, just the chipset of one. \$\endgroup\$ Aug 21, 2020 at 17:11
  • \$\begingroup\$ @MarcusMuller Can you indicate one such chipset? \$\endgroup\$
    – Cristian M
    Aug 21, 2020 at 17:51
  • \$\begingroup\$ something like the sierrawirless airprime hl? \$\endgroup\$ Aug 21, 2020 at 18:50

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I would like the host system's Linux to use PPP to connect to the internet via the module and to be able to send/receive SMS at the same time.

So, the usual: AT commands for both

So, I will need at least 2 USB virtual ports for these two capabilities.

no, why should you?

Modems have (and have had since AT commands became a thing) something called "escape sequence" with which your host can escape from data communication and issue new commands.

I've seen in the hardware design document that 4 virtual ports are available: audio, AT, diagnostics and NMEA. I guess the AT port will be used for the PPP connection.

Note that this really is a setup as you'd see it in a modem for deeply embedded systems, less than for high-speed data comms with a fully fledged Linux host.

It's pretty common these days that USB LTE modems do have an endpoint for AT commands (i.e. a "CDC device"), but also a separate network card endpoint for IP packets. You might want to check whether the device you're planning on using is really what you want, or whether a more consumer-typical LTE modem isn't what you're after, considering your rich host.

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  • \$\begingroup\$ The module will be used in an embedded system with a system on chip running Linux. If I use an escape sequence, will it interfere with the ongoing data communication (using PPP)? \$\endgroup\$
    – Cristian M
    Aug 21, 2020 at 17:13

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