Node-RED Pythonshell Raspberry Pi

[Alexandru89]

Hi all,

I would like to run in Node-RED a python script using a python shell block.
After adding the location of the .py script inside the block settings and adding a simple debug window the output is empty.
The location of the py script is in /home/pi

Could you please let me know what I'm doing wrong?

[edje11]

Is the python script working from the command Line?
Maybe you can share the script also with is.

[Alexandru89]

Hi Edje11,

Thanks for your quick reply.
Basically it's just a print command

[jbudd]

Are you sure the wires are connected to the pythonshell node? Try moving it to check!

I see that pythonshell has not been updated for 4 years and it seems to offer little beyond the standard exec node.

[{"id":"5e22caee442ca855","type":"exec","z":"5a97c57f1d60d64e","command":"python /home/pi/hello.py","addpay":"","append":"","useSpawn":"false","timer":"","winHide":false,"oldrc":false,"name":"","x":490,"y":400,"wires":[["012e4d81039d268a"],[],[]]},{"id":"7760edc8fca2d9a3","type":"inject","z":"5a97c57f1d60d64e","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":220,"y":400,"wires":[["5e22caee442ca855"]]},{"id":"012e4d81039d268a","type":"debug","z":"5a97c57f1d60d64e","name":"debug 5","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":740,"y":400,"wires":[]}]

[HaroldPetersInskipp]

Add #!/usr/local/bin/python to the top of your script and

Check the box marked Continuous

You shouldn't need the inject node either. (not for this script anyway)

[dynamicdave]

I couldn't get that node to work - gave up in the end. However using the 'exec' node works really well.

Got it working transferring FTP files to/from local and remote servers and run a script on my local Pi.

As an example, I've just added a new part to my flow to add two numbers together using a Python script in the Pi that is running Node-RED. This also shows how to pass parameters/values to the Python script.

Here's a copy of what's in function node 'Run Python script on .152' - the Pi that's running Node-RED.

Note: Depending on the version of Python you are running, you might need to change line-4 to...
msg.payload = "python /home/....etc...

And here's what's in the Python script located at /home/pi/adder.py

#!/usr/bin/env python3
import sys

a = int(sys.argv[1])
b = int(sys.argv[2])
# c = int(sys.argv[3])
result = a * b
print('Result of multiplying ',a," by ",b, " is ",result)
print(result)

This is how I set-up the 'exec' node.

Hope this helps to get your hello.py script working.

[jbudd]

@HaroldPetersInskipp

Add #!/usr/local/bin/python to the top of your script and

I don't think that's going to help.

On my Raspberry Pi (Raspberry Pi OS Bullseye) there is no such file as /usr/local/bin/python.

On the other hand It won't do any harm either. The pythonshell node seems to pass the script name as a parameter to python (cf python myscript.py), in which case a hashbang line is ignored.

[Alexandru89]

Thank you a lot for your advices!

Now it's working. It seems that my initial setup was correctly made. After I refreshed the Node-RED webpage it started to work.