Can't command anything through nutshell

Hi, I’m testing position control mode with motion capturing system. Publishing the topic /mavros/mocap/pose, I confirmed that mavlink module in PX4 firmware receives the topic meseages (in SITL mode).
However the PX4 rejects the position control mode. I wanted to check through nutshell what is going on the PX4 FMU but I can not type anything on nutshell. I remember that It works well one year ago. I’ve tried with firmware 1.5.3, 1.5.2, and 1.4.4 but none of them worked. I think something is wrong with my device permission setting…but I don’t know what to do. Please help me.

Seems the new 1.5.x disabled the USB connection to nsh tty. So you have to use the debug port to connect to it.

Thank you for your help.

No, the USB connection is not disabled, it just runs mavlink. You can get a nuttx shell via mavlink with the script: