How can I UART initializtion?

Hello,

I am newbie about px4.

I have had some problems.

I want to connect from px4 to computer.

so I did be programming serial transmit program.

And then I successed about open serial. But I couldn’t receive any data.

Just I could see “Timout out”.

So I had to connect using qgroundcontrol and then exit it. After that, I could receive px4 data.

My option is Port is COM4, BaudRate is 57600, DataBits is 8, and so on.

How can I UART initializtion??