In this chapter, we are going to do something different to what we did in the other chapters. What we did so far was measure some data on the Arduino board and transmit this data back to the network using the Ethernet shield. In this chapter, we are going to control a device instead of measuring data.

To do so, we will use a relay connected to the Arduino board with the Ethernet shield and control this relay remotely. We are also going to connect a set of power cables to this relay so you can directly plug a lamp into it so that it can be controlled remotely.

In the first part of the chapter, we are going to control this relay remotely within your local network. In the second part of the chapter, we will use a dedicated web service to control this relay from anywhere in the world.

The following will be the major takeaways from this chapter: