raspberry gpi pin state when stopping node-red

[Kovacs Alpar]

Hi,

I have a flow to control some relays with raspberry. The only problem is that when I stop/restart node-red my the GPIO pins set for output will got to state of 0.

This pins initialize to the desired state on startup. Is there a way to do the same nodered shutdown?

Alpar

[Dave C-J]

At the the close we call GPIO.cleanup() which is the recommended thing to do.

eg see. http://raspi.tv/2013/rpi-gpio-basics-3-how-to-exit-gpio-programs-cleanly-avoid-warnings-and-protect-your-pi

After that we no longer have control of the GPIO so they will default to whatever the system sets them to, before we re-start and get control.

In theory you could try removing GPIO.cleanup from the nrgpio.py file - but I'm not going to apply that generally.

[Kovacs Alpar]

I removed GPIO.cleanup nothing changed. When I stop the node-red service all pin that is set to be digital output going to low value instantly. In the documentation linked by you I read that GPIO.cleanup should set this pins to digital input.

I suspecting that  this command  not executed when the service is stopped ( with SIGINT)

[Kovacs Alpar]

finally I found  a possible solution.

I modified the the nrfpio.py file to catch the SIGINT signal ( this signal stop the node-red service in raspbian):

import signal

def signal_term_handler(signal, frame):

GPIO.cleanup()

sys.exit(0)

signal.signal(signal.SIGINT, signal_term_handler)

it's ok now, when I stop the service all my GPIO port resting to input according with the documentation.

As I'm not an experimented programmer , I'm not absolutely sure about this workaround so any feedback is appreciated :)

[Dave C-J]

looks like a sensible fix to me - I'll give it a whirl and apply it to core as long as it works. (can't see why not)

[NodeIdea]

Hi,

I'm trying to control my relays on temperature difference with Pi?NodeRed too. What does yours do?

[Dave C-J]

Hi Kovacs

I tried your solution today. I added some output to the call, but never saw it called. How exactly are you stopping it ? By ctrl-break or node-red-stop ?

[Kovacs Alpar]

2016. március 15., kedd 1:40:19 UTC+2 időpontban Dave C-J a következőt írta:

Hi Kovacs

I tried your solution today. I added some output to the call, but never saw it called. How exactly are you stopping it ? By ctrl-break or node-red-stop ?.

Hi Dave,

I stopping with node-red-stop or service nodered stop, both command do the same. On the service description file (/lib/systemd/system/nodered.service on my pi) I have :

# Use SIGINT to stop

KillSignal=SIGINT

it mean for me that the service is stopped with the SIGINT signal

[Kovacs Alpar]

Hi Nodeldea,

I'm controlling my relay on temperature difference like you

[NodeIdea]

Alpar,

Can you give me some help please? I sent you a pm.

THanks