EC20 AT command communication problem

Hello, when trying to communicate with EC20 quectel module, some times the module is not responding to the AT command executed. What could be the source of problem? using baudrate 115200-8N-1 with CR-LF at the end of AT command.
Thanks

Dear Ahmed Kamel,
Thanks for your inquiry in Quectel forum.
For your issue, it is better to provide your test AT log, then we can help to confirm the reason. You use UART port or USB port ? Normally, if you use the right port, and choose the correct baudrate, it should have no issue to send AT command, and maybe some command response time is too long, it may need wait for the response of the previous AT command, then to send the next command. Thanks!

@Ahmed_Kamel did you resolved this issue ? since I am facing similar issue. AT command response in USB port but not in UART.

tried
sudo minicom -D /dev/ttyAMA0 -b 115200

then typing “AT” returns nothing.

Please help!