> 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

Information for older P1 Modbus adapters that still use legacy firmware v1.

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.