[Solved]Abnormal signal of QSerialPort

[Ivan1120]

Hi guys:
Recently, I used QSerialPort module in my project and i found something is weird. Whenever I replug-in serial port to computer, the sending data from QT using QSerialPort is abnormal, next I use project by C# open comport and send, the data is correct. And I change back Qt project again, doing the thing as same as first I tried, the sending data is correct.
I have tried about more than 3 times, this situation was keeping to exist. Does anyone know why or have same experience like me? Thanks for responds in advance.

BTW, the related functions about QSerialPort are all return true, it means the function really did right things I program.

[hskoglund]

Hi, maybe in your Qt project you do not set transmit speed on the serial port (but you do in your C# project).

[kuzulis]

Also please use open() before setXX() methods in case you use Qt 5.2. and to check your return values again.

[Ivan1120]

Hi, above guys. I have checked that the things you mentioned, they are all respond true for me. And I also catch signals through oscilloscope, the signal is not really normal, because they always under 0V.

[kuzulis]

Then please provide an minimal example to reproduce an problem. Besides, please specify your type of serial port (what chip?)

[Ivan1120]

Hi, you can refer example that named "Terminal". The chip is FTDI. Is this only exist in my computer? I give the application to other people, everything is OK. But in my computer, the same issue still exist.

[kuzulis]

But in my computer, the same issue still exist.

Only you himself can to help itself to solve this problem.

Btw, the FTDI devices should be work fine.. You can try to update an FTDI driver and so on..

[Ivan1120]

Thanks. I resolved this problem after i reinstalled driver of comport device.