I am trying to figure out how to send UDP datagram over cellular modem. There is usually an AT#SD command that allows the modem to package the UDP pocket, but I want to package the pocket, including header, CRC and the data, and then send it over the network. What would be my starting point?
It isn’t clear what it is that you need to do. What is thereason that you don’t want to use the modem’s built in UDP transmission method? If you do want to use the packet services build in to themodem (via command line), then the best solution would be to operate the modemas a PPP stack. That would allow you to use an OS such as Windows or Linux anduse the OS IP stack.
To operate the device as a modem, then you will still needto set the PDP context
AT+CGDCONT=1,"IP","neo.iot.net" Note: APN setting may be different for your account
Activate the context and enter the data state ATD*99***<cid>#<cr> This should be done via a dialer to initiate the PPP stack In linux use the wvdial or similar In windows set this line up as a dial-up modem
When this is successful, you will have an IP connection to the network. You can then use any higher level IP service