I am designing a Garden watering system where I will have several Remotes around the yard. I would like to be able to communicate to selected Remotes from the Master to obtain their Readings.
In the Master, I would like to just have one routine that talks to the remotes by having a Variable containing the Address of the Remote I want to talk to, and send it requests for information. These remote addresses would be in an array where I could scan each remote using the array of remote addresses.
I am not sure if I can do this or not… I would think by supplying the address, I could do that… but, ???
Would all system Remotes have to receive The Request being sent to determine if They were the remote being addressed? The remote would acknowledge the request by sending the information requested back to the Master.
Could the remotes, some how be put to sleep to conserve battery power and then Triggered from the Master to wakeup and Talk, etc.?
Can anyone shed light on this? Would save me a lot of time possibly trying to do something that can’t be done. 
Some of the remotes would report information, Soil Moisture, temp, humidity, etc. while other remotes would Turn Water sections ON / OFF or perform other actions. The Master would be controlling all actions.
Looks like I have the choice of how I talk to the remotes: NRF24L01, WiFi, or 433mHz. Which one do you think would be the best? Reliable? Easiest to use?
Thank you very much,
Joe