Hoping I am not showing my lack of knowledge in asking this question. 

Over the past 5 years I am now on my third irrigation controller.  I was wondering if anyone has wired up a Pi to activate a relay to control an irrigation valve.  

Using a request command, I can get a value from the ISY to indicate whether I need to irrigate.  So my ISY logic would still be useful. 

Just wonder if anyone has considered or actually put in place this alternative.  

Thank you

12 hours ago, LarryCRetired said:

Hoping I am not showing my lack of knowledge in asking this question. 

Over the past 5 years I am now on my third irrigation controller.  I was wondering if anyone has wired up a Pi to activate a relay to control an irrigation valve.  

Using a request command, I can get a value from the ISY to indicate whether I need to irrigate.  So my ISY logic would still be useful. 

Just wonder if anyone has considered or actually put in place this alternative.  

Thank you

Short answer, yes.

Longer answer, you can use the Pi GPIO to trigger a relay. You could write a nodeserver to do that using the ISY programs. Exactly what would be needed as an intermediary so as not to burn up the Pi would need research. I did this to control a garage door. Here is the link to that GitHub: https://github.com/markv58/UDI-GarageDoorPi

For myself, not having an irrigation system and only wanting to take care of the ornamentals, I chose to go the LinkTap direction. There is already a nodeserver for that.

Thanks Mark.  I am taking a look at what you suggested.  Also a google search has left me with some ideas and more questions.   Been 50 years since I had a transistor course.  Thanks again

Some might suggest a Pi might be more than needed.  There's plenty of guys running ESP8266 microcontrollers, flashed with tasmota, with relays to run an irrigation system.  Here's one example.  There is a node server for mqtt setup to use tasmota (might need tweaked to use a relay board).

Dan. Very nice.  I just noticed your post.  Thanks for the pictures of the enclosure.  That is something I want to add once I am finished

In the mean time I was able to put together a left over Pi  and a gang of 4 relays.  My biggest hurdle was overcoming the relays closing when the Pi started or rebooted.   I solved the issue by using GPIO Pins that are HIGH on startup.  I am designing a PCB to take a wall wart at 9 volts and convert to 5 volt DC for an external power supply to energize the relays.  I am also adding LED indicators for each valve as it operates  

i wanted to use my ISY as the source for determing when to irrigate since all my rainfall data was accumulated in the ISY from a weather station .2 miles away.  Everything is on a breadboard as I am awaiting the parts from Mouser and Amazon.

i have an ESP in my box but have not taken the time to learn how to use it   Maybe next winter

thanks again