Monitoring data on UART1 FSU20.

Hi all,
I want to monitor data on UART1 in FSU20. I simply put pin code and then connect with private APN using windows connection (dial-up) software. I want to know it data flow still occurs, and after 10 minutes inactive to be able to reset modem (at+cfun=1). I found some functions adl_portGetSignalState but with that I can only monitor CTS and DSR. I want to know if TX and RX are still active - i don’t care what data is transmitted. Do you have any idea how to do that. Maybe some better solution than monitoring lines.

best Regards,