MH-Z19B Reading problem

KyleGabriel · May 13, 2022, 6:13pm

Have you searched similar issues on github? Here are some:

MH-Z19B: CO2 Sensor Error

opened 08:31PM - 15 Mar 22 UTC

closed 02:52AM - 16 Mar 22 UTC

### Describe the problem/bug *MH-Z19B CO2 sensor error. Specifically I was s…uccessful in reading the sensor from CLI using a python script to confirm the sensor is functional.* ![image](https://user-images.githubusercontent.com/81479977/158465749-0c1dcb41-7170-4519-975a-deb17fadc99c.png) ### Versions: - Mycodo Version: *8.12.9* - Raspberry Pi Version: *4B* - Raspbian OS Version: *Bullseye* ### Reproducibility Please list specific setup details that are involved and the steps to reproduce the behavior: 1. *Connect sensor.* 2. *Configure sensor.* 3. *Activate sensor.* 4. *Check live measurements page.* 5. *Check daemon log to confirm its not working.* ### Expected behavior *The sensor to show up in the "Live Measurements" page once correctly configured.* ### Screenshots ![image](https://user-images.githubusercontent.com/81479977/158466863-20d7438e-a77a-4fd1-8d65-8507d68e6e93.png) *![image](https://user-images.githubusercontent.com/81479977/158464987-2260d0e3-7ba3-4878-9e45-c87ab322c4c5.png)* ### Additional context (Daemon log) *ERROR - mycodo.controllers.controller_input_b1cf440c - initialize_variables() Exception: Write timeout Traceback (most recent call last): File "/var/mycodo-root/mycodo/controllers/base_controller.py", line 74, in run self.initialize_variables() File "/var/mycodo-root/mycodo/controllers/controller_input.py", line 317, in initialize_variables self.measure_input = input_loaded.InputModule(self.input_dev) File "/home/pi/Mycodo/mycodo/inputs/mh_z19b.py", line 130, in __init__ self.initialize_input() File "/home/pi/Mycodo/mycodo/inputs/mh_z19b.py", line 149, in initialize_input self.abcon() File "/home/pi/Mycodo/mycodo/inputs/mh_z19b.py", line 205, in abcon self.ser.write(bytearray([0xff, 0x01, 0x79, 0xa0, 0x00, 0x00, 0x00, 0x00, 0xe6])) File "/var/mycodo-root/env/lib/python3.9/site-packages/serial/serialposix.py", line 636, in write raise SerialTimeoutException('Write timeout') serial.serialutil.SerialTimeoutException: Write timeout*

github.com/kizniche/Mycodo

MH-Z19b Issue.

opened 06:46PM - 21 Jun 21 UTC

closed 02:47AM - 30 Aug 21 UTC

ghost

I have seen similar issues, but in the past it says they have been patched throu…gh updates. And those posts are YEARS old. ### Describe the problem/bug Co2 sensor works perfectly with my Pi 2. Switch it to my Pi 4 with all the same updated OS and Mycodo. Wont run and gives me error messages. ### Versions: - Mycodo Version: [latest version] - Raspberry Pi Version: [4] - Raspbian OS Version: [Raspian, most recent version] ### Reproducibility Please list specific setup details that are involved and the steps to reproduce the behavior: 1. Start up Mycodo with the Co2 sensor attached 2. Rx to Tx, Tx to Rx. gnd to gnd, pwer to 5v 3. activate sensor with default uart path. 4. See error ### Expected behavior I use this sensor on my Pi 2 with no issues. The Pi 4 gives me this. Traceback (most recent call last): File "/var/mycodo-root/mycodo/controllers/base_controller.py", line 74, in run self.initialize_variables() File "/var/mycodo-root/mycodo/controllers/controller_input.py", line 317, in initialize_variables self.measure_input = input_loaded.InputModule(self.input_dev) File "/home/pi/Mycodo/mycodo/inputs/mh_z19b.py", line 130, in __init__ self.initialize_input() File "/home/pi/Mycodo/mycodo/inputs/mh_z19b.py", line 151, in initialize_input self.abcoff() File "/home/pi/Mycodo/mycodo/inputs/mh_z19b.py", line 199, in abcoff self.ser.write(bytearray([0xff, 0x01, 0x79, 0x00, 0x00, 0x00, 0x00, 0x00, 0x86])) File "/var/mycodo-root/env/lib/python3.7/site-packages/serial/serialposix.py", line 636, in write raise SerialTimeoutException('Write timeout') serial.serialutil.SerialTimeoutException: Write timeout