IOCAN

# System Input

## Overview

A **System Input** exposes an **internal system value** — a quantity produced by the

controller itself rather than measured on a wire. **Which** value it reads is chosen

by the **pin**, which acts as a selector. Available values are:

- **Battery voltage** — the supply/battery voltage at the controller.

- **Ignition status** — whether ignition is on.

- **5 V measurement** — the controller's internal 5 V rail reading.

Use it to bring one of these into your configuration so other IO can reference it

by alias.

## Prerequisites & hardware

- **None to wire.** A System Input reads an internal value, so there is no sensor

  and no source input.

- You only need to choose **which** system value to read — done by the pin/selector

  (see below).

## Add it in the app

1. Add a new input and choose **System Input** as the type.

2. Choose the **pin / selector** — this picks which system value the input reports

   (Battery voltage, Ignition status, or 5 V measurement).

3. Give it a clear **alias** (e.g. the name of the value you selected).

## Settings reference

This input has **no type-specific settings**. Which system value is read is chosen

by the **pin / selector**, not by any field on the input.

## Common settings

System Input also uses the shared settings — alias and pin. Here the

**pin** is the selector that picks the system value. See

[Common IO Settings](Common_IO_Settings).

## Example — low-battery warning

1. Type **System Input**, selector **Battery voltage**, alias `Battery V`.

2. Feed `Battery V` into a [Compare Input](Compare_Input) set to

   `LessThan 11500` (mV) to flag a low battery.

## Troubleshooting

- **Reads an unexpected quantity:** the **selector** is set to a different system

  value — reselect Battery voltage / Ignition status / 5 V measurement.

- **Other IO don't see it:** check they reference the correct **alias**.

## Related

- [Virtual Input](Virtual_Input) — an externally-written value with no hardware.

- [Constant Value Input](Constant_Value_Input) — a fixed configured value.