IOCAN

# Scaling & Maps

Many inputs read a **raw** value (a voltage, a frequency, a CANbus signal) that

must be converted into a meaningful **engineering value** (°C, bar, rpm…). There

are two ways to do that conversion, from simplest to most flexible.

> Schema: the *in/out* scaling fields of `config/AdcConfiguration.proto` and

> `config/CanbusInputConfiguration.proto`; the 1D map in

> `config/MapInputConfigData.proto` / `config/MapOutputConfigData.proto`.

## Two-point interpolation

The simplest conversion is a straight line defined by **two points**: a low point

and a high point. You give the raw value and the engineering value at each end,

and everything in between is **linearly interpolated**:

```

output = out_min + (raw - in_min) * (out_max - out_min) / (in_max - in_min)

```

- **In min → Out min** and **In max → Out max** define the line.

- Values between the points are interpolated; values outside can be clamped

  (saturated) or extrapolated, depending on the input's settings.

Two-point interpolation is built directly into **analog inputs** and **CANbus

inputs** via their *in/out* scaling fields. Use it whenever the sensor is

**linear** — for example a 0.5–4.5 V pressure sensor reading 0–10 bar.

## Multi-point scaling

When a sensor is **non-linear** (e.g. an NTC temperature sensor), two points are

not enough. Use a **[Map Input](Map_Input)**: a 1D lookup table of

*raw value → output value* with as many points as you need, interpolated between

points along the curve. Feed the raw input into the Map Input and reference the

Map Input's output as your scaled channel.

The matching **[Map Output](Map_Output)** applies the same kind of 1D

lookup on the way to an output.

### Editing a map

- Enter the raw value on the X axis and the engineering value as the output.

- Keep X values strictly increasing.

- Add points where the curve bends; the controller interpolates between them.

> The map's internal interpolation type is managed by the controller and is not

> something you normally set.