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.

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.

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 ...