> 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-v3-all-modbus-rtu-adapters/firmware-v3.md).

# Firmware v3 overview

Firmware v3 for Smart Meter Modbus RTU adapters, including the Custom Modbus mapping expert feature.

Firmware v3 is the current software generation for all **Smart Meter Modbus RTU adapters**, including P1 Modbus Pro (NRGD) and D1MC. It retains the selectable standard Modbus mappings and Device Manager workflow from v2, and adds a custom mapper for systems whose required register layout is not available as a standard profile.

{% hint style="info" %}
Firmware v3 is available for every current Smart Meter Modbus RTU adapter. [Firmware v2](/p1-modbus-dongle/firmware-v2-existing-installations/firmware-v2.md) remains available for existing installations.
{% endhint %}

## Main V3 features

* **Custom Modbus mapping:** create a register layout for a controller, inverter, charger or energy-management system that is not covered by a supplied profile.
* **Verified starter mappings:** start from a Smartstuff-provided SDM630, inverted SDM630 or P1M floats mapping, then adapt it for the installation.
* **Import and export:** save a custom mapping as JSON, share it with an installer or keep it as a backup before changing it.
* **Persistent custom profile:** one custom mapping is stored on the adapter and can be selected as its active Modbus mapping.
* **Flexible register handling:** choose the register address, smart-meter value, scale, signed or unsigned data type and 32-bit word order. You can choose whether registers outside the mapping return zero or a Modbus error.
* **Improved data foundation:** the internal energy-data model has been renewed while preserving the established behaviour of the standard mappings.

## Device Manager navigation

After connecting, the Device Manager shows **Refresh** and **Save** in its secondary navigation bar. Firmware v3 adds **Custom mapping · Expert** there. The button is available only when the connected adapter confirms that it supports the mapper; it is not shown on firmware v2.

<figure><img src="https://869162580-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F50CFzoSHtUAx13D3ZcfB%2Fuploads%2Fgit-blob-80fbcb9f54a346c9168756afadd4c43936fad55e%2Fdevice-manager-v3-sub-navigation.png?alt=media" alt="Device Manager subnavigation with Refresh, Save and Custom mapping Expert"><figcaption><p>The custom-mapper entry point in the firmware v3 Device Manager.</p></figcaption></figure>

## Standard mappings remain available

V3 does not replace the standard mappings. Choose the supplied mapping when it exactly matches the connected system; it is the simplest and supported choice. Use a custom mapping only when no supplied mapping fits, or when the target system requires a small, well-understood variation.

The available standard profiles also include **SDM120 - Total system** in v3, in addition to the profiles documented for firmware v2. The Device Manager shows the profiles supported by the connected adapter.

## Getting started

1. Install the V3 Alpha with the [web installer](/p1-modbus-dongle/firmware-v2-existing-installations/update.md).
2. Connect the adapter and first select a standard mapping if one fits the target system.
3. If it does not, open **Custom mapping · Expert** in the Device Manager.
4. Start with a verified mapping or create one, validate it and upload it to the adapter.
5. Select the uploaded **Custom mapping** as the active Modbus mapping and test the registers with the connected system.

For the complete workflow, limits and important compatibility notes, see [Custom Modbus mapping](/p1-modbus-dongle/firmware-v3-all-modbus-rtu-adapters/custom-mapping.md).