Hi there , I was debugging UART in a LTE module running on openlinux I could get the data signals when I probe between TX <-> RX ( with ground connected)  ( The frame format was correct ) but when i probe it by connecting it to only TX ( with ground connected ) I don't get the data signals on the oscilloscope . Please let me know the actual behavior of the UART ? Is this behavior correct or wrong ?

Try looking on RX? 

Hi there , I don't get the data signal on oscilloscope if I connect the probe only to TX or RX . but if I connect TX & RX ( loopback ) and probe in-between them I get the data signals and are perfect.