> For the complete documentation index, see [llms.txt](https://docs.smart-stuff.nl/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.smart-stuff.nl/p1-modbus-dongle/firmware-v1-legacy/firmware-v1.md).

# Firmware v1 overview

Firmware v1 is the legacy firmware generation for older P1 Modbus adapters. Each mapping or use case is delivered as a separately compiled firmware variant with its own defaults. It remains documented for existing installations, but current products and new integrations should use firmware v2. Firmware v1 does not support D1MC.

{% hint style="info" %}
Existing P1 Modbus adapters with firmware v1 can be migrated to firmware v2. See [Migrate from v1 to v2](/p1-modbus-dongle/firmware-v1-legacy/migrate-to-v2.md).
{% endhint %}

## How v1 differs from v2

* The Modbus mapping is selected by installing a specific firmware variant.
* Default device ID, baud rate and serial format may differ between variants.
* Configuration is primarily performed through Modbus registers and the physical button.
* The firmware does not provide the complete v2 Device Manager experience.

Firmware v1 therefore behaves fundamentally differently from v2: changing the application or mapping generally means selecting and installing another firmware variant.

## Legacy register mappings

The existing v1 mapping reference has been retained under [Firmware v1 register mappings](/p1-modbus-dongle/firmware-v1-legacy/register-mapping.md). Mapping availability, device ID and serial defaults depend on the specific v1 firmware variant installed on the dongle.

{% hint style="warning" %}
Before changing or updating a v1 installation, record the installed mapping, device ID, baud rate and serial format. These values are needed when selecting or configuring the replacement firmware.
{% endhint %}

## Updating a v1 dongle

Legacy firmware variants and recovery installation remain available through the [P1 Modbus web installer](https://install.smart-stuff.nl/p1m/).

When upgrading to v2, reconnect through the [Device Manager](https://config.smart-stuff.nl/) and select the required mapping and communication settings after installation.

## Existing integrations

There is no need to upgrade a stable v1 installation solely because v2 is available. Migration is supported and recommended when you need configurable mappings, Device Manager support, newer emulations, monitoring or integrated firmware updates.