USB TTL cable no longer working

[taros]

I dont know anything but try to switch rx and tx?

My suggestion same as longsleep.

I switched RX and TX but I still did not get any output.

Code:

$ cu -l /dev/ttyUSB0 -s 115200
Connected.

When I plug in the RX cable, the green LED lights up at half intensity. 
When I plug in the power, the green LED lights up at full intensity. 

My next step is to try out the UART cable on another working device.