Domoticz Community Forum - Support & Discussion

## Important installation and configuration instructions

Before using DSVT for the first time, please follow these steps carefully. These requirements are particularly important for new Domoticz installations.

### 1. Required Domoticz settings

**Geographical location**

Open **Setup → Settings → System** and enter the actual latitude and longitude of your installation.

DSVT uses these coordinates for location-dependent weather forecasts and temperature calculations. Incorrect or missing coordinates may result in inaccurate heating and cooling control.
**Local API access**

Open **Setup → Settings → Security → Trusted Networks (no username/password)** and add:

`127.0.0.1`

Click **Apply Settings** to save the configuration.

This setting is essential because DSVT communicates with the local Domoticz API to create and update user variables and perform other control operations.

Without this permission, Domoticz may reject API requests with **401 Unauthorized**, preventing important parts of DSVT from functioning correctly.
### 2. Create the DSVT hardware first

Open **Setup → Hardware** and select:

**DSVT + HMV (DHW) + 12 ZONE**

Create the hardware entry with the optional configuration fields left empty. Do not attempt to configure all zones and devices at this stage.

Click **Add** to create the plugin.

**Important: The dedicated DSVT HTML configuration interface becomes available only after the DSVT hardware has been created.**
### 3. Configure DSVT using the HTML interface

After creating the hardware, open:

**Custom → HTML setup!**

This is the dedicated administration interface for configuring the heating and cooling zones, heat sources, DHW, buffer tanks, mixing valves, sensors and other operating parameters.

**Do not try to perform the detailed configuration through the standard Domoticz hardware settings.** Those fields are not intended for the complete DSVT configuration.

**Important: Check your Domoticz user permissions.**

The Custom menu may not be accessible to ordinary users by default. Make sure the account you are using has sufficient permissions to view and access the Custom menu.

If the HTML setup page is not visible, first check that the DSVT hardware has been created, the HTML interface files have been installed correctly, and your user account has the necessary access rights.

### Documentation

The complete installation instructions, configuration guide and additional screenshots are available on GitHub:

https://github.com/szelessavalapitvany/Domoticz-DSVT

Please follow this installation sequence to avoid unnecessary configuration and initialization problems.

**Important installation update**

Apologies, we overlooked a few installation details that have become routine for us after years of working with Domoticz.

In particular, we did not initially mention two important settings:

- Configuring the actual geographical coordinates in Domoticz.
- Allowing local API access for `127.0.0.1` under **Setup → Settings → Security → Trusted Networks**.

We also clarified the initial setup procedure: DSVT hardware must first be created with empty configuration fields. Only then does the dedicated HTML configuration interface become available under the **Custom** menu.

Please also make sure your user account has permission to access the Custom menu.

These details are particularly important for fresh Domoticz installations and may otherwise cause initialization or configuration problems.

**We have now updated the first post with detailed instructions and screenshots**, and the GitHub README has been updated as well.

https://github.com/szelessavalapitvany/Domoticz-DSVT

Thank you for your patience and understanding. We appreciate any feedback, especially from users installing DSVT on a fresh system.

**Bug fix – Selector Switch initialization on fresh Domoticz installations**

During testing on a fresh Domoticz 2025.2 installation, we discovered an initialization issue that may also affect certain other Domoticz versions.

Some Selector Switch devices could appear as **"undefined"** or **"Invalid?"** instead of displaying their configured default state.

The issue was related to the initial `nValue` and `sValue` combination used when creating these devices.

For example, the previous initialization was:

`devicecreated.append(deviceparam(2, 0, "10"))`

The corrected initialization is:

`devicecreated.append(deviceparam(2, 1, "10"))`

For Selector Switch devices initialized in an active state, `nValue` is now set to `1`, while switches initialized in the Off state retain `nValue=0`.

**The fix has been committed to GitHub.**

Users are advised to update the DSVT plugin to the latest version.

Repository:
https://github.com/szelessavalapitvany/Domoticz-DSVT

Thank you for your patience as we continue testing DSVT on clean Domoticz installations.