ser = serial.Serial('/dev/ttyUSB0', 19200)
Does your firmware really ask for just 19200 baud? More typical are 115200 or even 250000 baud. 250000 baud don't work so well on Linux, though.
Does your firmware really ask for just 19200 baud? More typical are 115200 or even 250000 baud. 250000 baud don't work so well on Linux, though.