Can't get MH-Z19B to work

Ok I’m a complete idiot and i can’t figure out how to get the sensor to work. It’s constantly showing 0ppm. I’ve tried to follow the configuration instructions but i still don’t understand it and can’t get the thing to work.

Can you please help me with a simple step by step idiot proof guide to setting it up?


Hi Jesse,

What instructions are you referring to?

Can you describe how you’ve connected it, ideally with photos and descriptions of what’s not obvious from the photos?

Thanks for replying .
I was talking about the ‘mycodo configuration’ section of the build article on your site saying to make sure the UART input is set to /dev/ttyUSB0.

Anyway I’ve got it working now, I realised I had the Tx & Rx wiring from the sensor to the UART USB adapter the wrong way round…

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:stuck_out_tongue_winking_eye:too good to read this. I am happy that finally you figured out