I almost gave up while reading tons of forums:(
I bought CO2 sensor MH-Z19 from aliexpress.
As I figured out this sensor used by RPi without any problems. Manual I found here:
I connected module as mentioned:
Vin - 2 pin gpio
GND - 9 pin
Tx - 13 pin
Rx - 11 pin
Module was blinking when I powered on my OPi, but when I tried to send data to UART nothing happened. I got timeout.
I tried to connect Tx and Rx (11 and 13 pin) by cable, then sent bytes and immediatley got answer, UART work, as I understood.
I checked uart in armbian-config menu and all (1,2,3) was enabled.
Orange PI PC Plus
Linux orangepipcplus 5.4.30-sunxi #20.02.9 SMP Mon Apr 6 19:46:24 CEST 2020 armv7l GNU/Linux
Can somebody help me, please?