> 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/migrate-to-v2.md).

# Migrate from v1 to v2

Older P1 Modbus adapters running firmware v1 can be migrated to firmware v2. The hardware does not need to be replaced. This procedure does not apply to D1MC, which supports only firmware v2 for Modbus.

{% hint style="warning" %}
Treat the migration as a new configuration. Record the current settings before installing v2; do not assume that v1 settings will be transferred automatically.
{% endhint %}

## Before migration

Record the settings used by the connected Modbus master:

* Installed mapping or v1 firmware variant
* Modbus device ID
* Baud rate
* Serial format, for example `8N1` or `8E1`
* Pre-v4 smart meter mode, if applicable
* RS485 termination setting, if available on the hardware

If possible, temporarily stop the inverter, charger, EMS or other Modbus master while changing the dongle firmware.

## Install firmware v2

1. Connect the P1 Modbus adapter to the computer using a USB data cable.
2. Open the [P1 Modbus web installer](https://install.smart-stuff.nl/p1m/).
3. Select the current P1 Modbus v2 firmware for the detected hardware.
4. Start the installation and keep the USB cable connected until it is complete.

## Configure the migrated adapter

1. Open the [Device Manager](https://config.smart-stuff.nl/).
2. Select **Connect** and choose the adapter.
3. Select the v2 mapping that corresponds to the previous v1 firmware variant.
4. Restore the recorded device ID, baud rate and serial format.
5. Restore any other required settings and select **Save**.
6. Verify that valid P1 telegrams and Modbus requests are visible.
7. Re-enable the connected Modbus master and verify its measurements.

After migration, future stable updates can be installed directly through the Device Manager without selecting the adapter a second time.