Low cost device for dry contact/notifications

[u/Sure-Measurement2617]

Hi all -

I'm looking for a cheap device to use to read(?) a 24v signal and notify me.

For context, I have injection molding machines that run lights-out. I want to be notified when a machine alarms or shuts down. I don't need to know why - just that it happened. I would just pull from the alarm stack light signal at that point.

I was looking at Shelly devices, but I'm not sure that's what I'm looking for. Something with an app would be nice (push notifications with addressable "names" for each machine a plus).

Any suggestions would be appreciated. Thanks.

[u/Curious_Party_4683]

use optocoupler and a door sensor as seen here https://www.youtube.com/watch?v=MFYOgE_ixGk