EC21EUGA in TRB142 modem doesnt reconize +++ in transparent mode

We are using Teltonika’s TRB142 modem which uses Quectel EC21EUGA modem inside. When modem is configured in full control mode, it is directly controlled using AT commands.
We manage to open socket, connec to server and send data in transparent mode, but when trying to exit data mode, nothing happens. Module does not react to +++ (writen closely following your instructions of time delay before and after sending it, and not using CR, LF at end of message). AT&D0 is configured.
connect command used:
AT+QIOPEN=1,1,“TCP”,“hidden”,5011,5011,2 \r \n, responsed by: CONNECT.
writing +++ just sends it as packet to server. Is there another way to define escape sequence (using only software approach, not DTR line)?

Hi Steronja,

“+++” is the only way to switch mode in software approach. Regarding writing +++ was treat as packet and sent to server, to prevent the “+++” from being misinterpreted as data, the following sequence should be followed:

  1. Do not input any character within 1s or longer before inputting “+++”.
  2. Input “+++” within 1s, and no other characters can be inputted during the time.
  3. Do not input any character within 1s after “+++” has been inputted.

Best Regards,