Difference between gateway and controller for beginners

[mainali]

I am just starting with IOT, after going through the wiki of openHAB found this site.

For beginners I have connected two arduino with raspberry pi using NRF2401L modules. Still reading on setting up openHAB on PI.
After going through this site I have a confusion. I understood openHAB is a controller. So, a raspberry pi with openHAB installed will mean that it is a "GATEWAY" ?.

I am trying to create a tree with PI on top and arduino as child and grandchild each of which will do some function. In my case where does the gateway comes in picture. Do I need one more arduino connected to PI through nrf2401L or a different type of connection which will act as my "gateway".

Some one with knowledge help me out to understand the use of gateway, why it is needed and how to start with simple one raspberry pi and two arduinos to begin with.

[Magiske]

You have 3 components.

Sensors. Arduino + Temperature Sensor + NRF2401 module.

Gateway. Arduino + NRF2401 + Ethernet/Serial interface. This is where the sensors sends data. So the gateway is a hub for all you sensors to connect to.

"Controller" In you case OpenHAB, I have a VERA running..

Sensors delivers data to Gateway.

Gateway talks to Controller and deliver sensor reading.

Your openHAB Pi is your control center where you read the data and/or execute rules ect.

/M

[axillent]

@mainali In my view your can distinguish between controller and gateway by understanding each other main function

For the controller the main function is scene management while for the gateway the main function is a route between radio sensors and the controller.

Because raspberry is a multitasking thing it should be possible to run opneHAB and ethernet gateway on the same hardware simultaneously. But I'm not sure is it any existing case of a such.