IOCAN

# Counter Input

## Overview

A **Counter Input** keeps a running count that goes **up** and **down** as trigger

inputs fire. Three inputs drive it: one increments, one decrements, and one

resets it. Use it to tally events — shift counts, button presses, fault

occurrences — or to maintain a step value you nudge up and down.

## Prerequisites & hardware

You need up to three **trigger inputs**, each referenced by alias:

- An **up** input that increments the count.

- A **down** input that decrements it.

- A **reset** input that reloads the reset value.

Triggers are typically boolean signals such as a [Compare Input](Compare-Input.md)

or a [Digital Input](Digital-Input.md); the counter steps on each trigger edge.

Any trigger you do not need can be left unset.

## Add it in the app

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

2. Choose the **up / down / reset** trigger inputs.

3. Give it a clear **alias** (e.g. `Shift Count`).

4. Set the **step**, the **min / max** limits, the **start** and **reset**

   values, and whether the count **rolls over**.

## Settings reference

> Schema: `config/CounterInputConfiguration.proto`.

| Setting | Meaning | Unit | Range / values | Notes |

|---|---|---|---|---|

| **Up input** | Trigger that increments the count | — | an existing input (by alias) | Counts up by **Step** on each edge. |

| **Down input** | Trigger that decrements the count | — | an existing input (by alias) | Counts down by **Step** on each edge. |

| **Reset input** | Trigger that reloads **Reset value** | — | an existing input (by alias) | When it fires, the count jumps to **Reset value**. |

| **Step** | Amount added/subtracted per trigger | count | int32 | The increment size. Usually `1`. |

| **Min value** | Lowest the count may reach | count | int32 | Clamp limit (see **Rollover**). |

| **Max value** | Highest the count may reach | count | int32 | Clamp limit (see **Rollover**). |

| **Start value** | Count at power-up | count | int32 | The value loaded when the controller starts. |

| **Reset value** | Value loaded on reset | count | int32 | What the count becomes when the reset input fires. |

| **Rollover** | Wrap around the limits instead of clamping | — | on / off | **On:** counting past **Max** wraps to **Min** (and below **Min** wraps to **Max**). **Off:** the count stops at the limit. |

**Edge triggering:** the count changes once per trigger event, not continuously

while a trigger is held. At the limits, **Rollover** decides between wrapping and

clamping.

## Common settings

Counter Input also uses the shared setting — alias. See [Common IO Settings](../Common-IO-Settings.md).

## Example — count gear shifts

1. Type **Counter Input**, alias `Shift Count`.

2. **Up input** = a [Compare Input](Compare-Input.md) that fires on each shift.

3. **Reset input** = a `Trip Reset` button input.

4. **Step** `1`, **Start value** `0`, **Reset value** `0`.

5. **Min** `0`, **Max** `999999`, **Rollover off** so it simply tallies up until

   reset.

## Troubleshooting

- **Count never changes:** check the trigger inputs actually toggle and that **Up

  / Down** are assigned.

- **Counts more than once per event:** the trigger is noisy — debounce it at the

  source (e.g. the [Digital Input](Digital-Input.md) filter).

- **Count wraps unexpectedly:** turn **Rollover off** to clamp at **Min / Max**.

- **Wrong value at power-up:** set **Start value**; after a reset it uses **Reset

  value** instead.

## Related

- [Compare Input](Compare-Input.md) — generate the trigger events to count.

- [Digital Input](Digital-Input.md) — count switch/button edges.

- [Frequency Input](Frequency-Input.md) — measure pulse frequency/speed instead.