MH-Z19b Issue.

[ghost]

I have seen similar issues, but in the past it says they have been patched through 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

[kizniche]

You're likely not setting the proper device.

[ghost]

can you elaborate. The input is set to the specific Co2 sensor. I am using all the same default options as the Pi2. Everything is replicated perfectly between the Pis. Im not sure how to proceed.

[ghost]

Why respond at all if you have no help to offer? I'm honestly shocked that you yourself scoffed this off with a one sentence reply giving me nothing to work with. I've donated in the past and was planning on doing so again as i use this software everyday. But this response has truly shocked me.

[kizniche]

It would only work on one and not the other if you didn't change the Device, because serial is set to different default devices on the Pi 2 and Pi 4. What do you have the device set to?

[kizniche]

I don't have to respond at all. I typed my last response before seeing yours. And frankly, I'm now dissuaded from replying again. I'm currently on vacation and I don't need to respond to any of this.

[kizniche]

Why respond at all if you have no help to offer?

You think telling you what the likely issue is isn't helping?

[ghost]

I apologize. Its my fault for relying on software to run my greenhouse. Im frantic and my words were childish.

[ghost]

the serial is Ama0 for pi 2, and Ama0 for pi4

[kizniche]

Try /dev/ttyS0

[ghost]

Warning: Invalid device or improper permissions to read device

[kizniche]

You used raspi-config to enable Serial and also answered No enabling login shell over serial?

[ghost]

im navigating to the docker-compose.yml to ensure permissions is set to true

[ghost]

no to shell, yes to serial port hardware

[kizniche]

You shouldn't be running Mycodo in Docker if it's on a Pi.

[ghost]

i meant, i saw this error in a past post, and you recommended then to edit the docker file permissions.

[kizniche]

try /dev/serial0 and if that doesn't work, try /dev/serial1. You can also ls /dev/serial* to see what serial devices there are if 0 or 1 doesn't work.

[ghost]

everything looks better, all i get now is a Bad Checksum

[kizniche]

Bad Checksum for every measurement? That indicates potentially the wrong device.

[ghost]

2021-06-21 12:12:06,620 - ERROR - mycodo.inputs.mh_z19b_0e85654c - Bad checksum

[ghost]

im getting live data, but its not recording any to a graphable format

[kizniche]

If it's showing on the Live page, it's being recorded in the database, which the graphs also query from. So it's likely that you may need to refresh your page for the graph to show the data or you might not have the measurement selected for the graph widget.

[ghost]

thank you so much for the help, and i apologize again for my anger. This software you pioneered has changed my farming life in ways i cannot express. Thank you and i will surely donate again soon.

[kizniche]

No problem, I know the frustration when things don't work as you expect them to. I'm on vacation and replying on my phone so it's easier to first explain the issue briefly because many times people only need guidance in the right direction. I'd rather not waste both our time writing a detailed response if it's unnecessary.

[kizniche]

This issue has been mentioned on Radical DIY Forum. There might be relevant details there:

https://forum.radicaldiy.com/t/mh-z19b-reading-problem/661/11