AT+CMGS hangs if command is misissued

[flotulopex]

Pedja,

May I kindly ask you what type of modem(s) you use?

[pedja089]

Started with sim300, then sim900D, now sim800C.
I think simcom is best modem for price.
There is at least 150 pcs in few different products, and I think that there is no failed modem in field. There was few that fail testing after assembly.
If you want to be sure that modems works reliable, you must have way to switch power off(for reason that you are trying to solve), good supply(low ESR caps, good regulation-no more than 0.2V drop on 1.6A pulse), and good antenna.
Flow control is optional.
Where I have large files to transver(10's of KB )I use flow control or if device can download new FW from FTP.
I had no luck with built in FTP client, so I stick to mine FTP and SMTP clients in PBP.

[flotulopex]

Thanks Pedja,

Where I live, 2G has been by end 2020 so I choose to go SIM7600E.

And thank you for all your usefull remarks

[flotulopex]

BTW,

In the AT command book for my module (SIM7600E), I finally noticed this:



There is no mention of this ESCape command in the datasheet, just here in this table. But, unlike it is appearing, even if I cancel the CMGS command, I will get an OK.

For any reason, I didn't understand that part of the DS (...as well as a lot of other parts, in fact ).

Anyway, the ESC termination command does the job and cancels the AT+CMGS command and yelds an "OK" which I can wait for to "move on".

Problem solved!

Richard, I did check the +++ command which is now allocated, in my module, to switch from data mode to command mode. But it was a good idea to mention it; thank you