Quectel chip QIMODE change with '+++' & 'ATO'

Question

I am trying to implement my library to send data over tcp connection.

In official documentation from Quectel they let you select AT+QIMODE=1 also called Transparent mode where all data sent from UART is sent over tcp connection.

I am trying to check connection status before sending data so would want to change to command mode and use AT+QISTAT. I tried sending '+++' to chip but it's sending '+++' to my server, so it's not working. Any help is greatly appreciated.

Link to official documentation, please refer to page 162 section 7.2.21

Answer 1

Have you ensured you have the correct time delay before and after the +++ sequence?

The documentation at section 2.2.11 (page 22) states that there must be a quiet period of 0.5 seconds before and after the +++ for it to be recognised.

To prevent the "+++" escape sequence from being misinterpreted as data, it should comply to following sequence:

1. No characters entered for T1 time (0.5 seconds).
2. "+++" characters entered with no characters in between. For CSD call or PPP online mode, the interval between two "+" MUST be less than 1 second and for a transparent TCPIP connection, the interval MUST be less than 20 ms.
3. No characters entered for T1 time (0.5 seconds).
4. Switch to command mode, otherwise go to step 1.

If you still don't have any success please post some example code.