How to read a control loop
A short field guide to inputs, setpoints, and outputs — the three things every control loop comes down to.
Placeholder copy — replace before launch.
Every control loop, no matter how elaborate, is doing the same three things: reading the world, comparing it to a target, and acting on the difference.
Inputs
Sensors report the current state — a temperature, a pressure, a CO₂ reading. Nothing happens until every input a loop depends on has reported at least once.
Setpoints
The target. A setpoint can be fixed, scheduled, or commanded at runtime. It’s the line the system is trying to hold.
Outputs
The action — a valve position, a fan speed, a relay. The output is whatever the loop writes back to the equipment once it has decided what to do.
That’s the whole shape of it. The art is in what happens between the input and the output — and that’s what the rest of this blog is about.