Serial port does not work

[danp]

Hi
I use like guest windows 7. But i have a problem with serial port. I have this setting:
Port: Com1
Physical serial port: /dev/ttyS0
On Win7, I get data from serial port, but I can not send data to serial port.
When i send data to serial port COM1, data will lose in Virtual box.
I tested this on three computers.
Connection does not work from guest Win7 to host Linux Debian 9

Thanks for your time.