The relay was very conservatively rated, both in terms of both current and voltage, and mounted on a generously sized heat sink. The system worked slick for a good two years, then one day, no heat.

Raspberry Pi GPIO control with Arduino Cloud is a crucial aspect of many Internet of Things ... enables users to control relays, monitor digital inputs, and visualize real-time and historical data.

Here, pin D12 of Arduino is used to drive a standard 5mm LED, and D13 is used to drive an Electro-Magnetic Relay through a transistor-based relay driver. Everytime the tag values match, D13 goes high ...

Any process control engineers out there want to take this on. As pointed out the basic PID controller is available from China for <$20. Its still up to the software to produce the benefits.