---
title: Configure the KNX or Modbus main meters of a Chart’nX dashboard
description: Enable the main meters of a Chart’nX energy dashboard and set the KNX address or Modbus configuration, index mode, unit and custom factor.
canonical: https://wiki.can-nx.com/en/guides/chart-meters/
language: en
product: Chart’nX
audience:
  - administrateur
  - installateur
context: "Chart’nX: energy generator, Main meters section"
---

# Configure the KNX or Modbus main meters of a Chart’nX dashboard

Context: Chart’nX: energy generator, Main meters section

The main meters feed a Chart’nX energy dashboard: apparent power drawn, total energy consumed, PV production, battery and electrical grid. For each card you use, you choose the source of the measurement, KNX group address or Modbus configuration, then the index mode, the unit and the factor.

For installers or administrators in charge of the project. For a three-phase measurement, follow [Configure per-phase measurements](https://wiki.can-nx.com/en/guides/chart-meter-phases/) instead.

## Before you start

- You know the meters, their measurements, their units and their addresses or Modbus configurations.
- The energy generator is open with **Configure** [from Emergy’nX](https://wiki.can-nx.com/en/guides/chart-open-emergy/), and the [general information](https://wiki.can-nx.com/en/guides/chart-general/) has been checked.

## Enable the meter card

1. Go to **Main meters**. Locate the card that matches the measurement: **General meters - Apparent power**, **General meters - Total energy consumed**, **PV meter** or **Grid meter**. The [battery](https://wiki.can-nx.com/en/guides/chart-battery/) has additional fields.
2. Turn on the switch to the right of the card title. The fields appear. Unused meters can remain disabled; to save the dashboard, at least one meter must be active or a submeter added.
3. If useful, fill in **Brand of the meter (optional)**, then choose **Protocol**: **KNX** or **Modbus** depending on the source of the measurement. For a calculated total, the total energy card also offers [Operations](https://wiki.can-nx.com/en/guides/chart-operations/).

## Fill in the measurement

1. In the measurement section, choose **Index** for a cumulative meter whose consumption is calculated as the difference between readings. Choose **Not indexed** when the value already represents the period or the instant. The question-mark icon recalls this distinction.
2. In KNX, fill in **Group address**. Type the address or select a suggestion showing its address and its name, then check that it is the right measurement.
3. In Modbus, open **Modbus Configuration** and choose the configuration for this measurement. The rows show the name, **U** followed by the unit identifier and **R** followed by the register address. Choose based on these parameters, not on a brand that resembles that of the meter. If the configuration is missing, see [the Modbus catalog](https://wiki.can-nx.com/en/guides/chart-modbus-catalog/) or [declare it](https://wiki.can-nx.com/en/guides/chart-modbus-config/) with the known parameters.

## Set the unit and the factor

1. In **Meter unit of measurement**, choose the unit of the received measurement: **Voltampere (VA)** or **Kilovoltampere (kVA)** for apparent power; **Watt-hour (Wh)** or **Kilowatt-hour (kWh)** for energy.
2. Check **Custom Factor**: it multiplies the meter value. A non-zero number is required. The value **1** keeps the value without additional multiplication. A negative factor inverts the sign; use it only if this choice is confirmed for the measurement concerned.
3. If needed, add the [overlays](https://wiki.can-nx.com/en/guides/chart-meter-display/), review the fields, then [save the dashboard](https://wiki.can-nx.com/en/guides/chart-save/).

Changing the protocol replaces the configuration fields of the measurement: review the address, the units, the index mode and any phases before saving. An empty display is not solved by changing the protocol.

## Add an old KNX address

1. In the meter card, under the main address, select **+ Add historical address**.
2. Enter the old address in the new **Historical** row. The card’s **Custom Factor** applies to the current address; the row has its own **Unit** and its own **Factor**, different from 0.
3. Save the dashboard to keep the change.

Repeat only for the old addresses of this same measurement, provided by the installer. An added row must not remain empty; the cross on the row removes it from the form. Adding an address does not reconstruct measurements that were never logged. To establish the continuity between two meters, the replacement dates or the priority of addresses whose data overlaps, contact support before validating this history recovery.

## Disable a meter or cancel the changes

Disabling a card removes it from the active configuration of the dashboard and keeps its fields for a reactivation; the device is not physically stopped. Check the calculations that use this meter, as a composition may become invalid. Before saving, [Cancel](https://wiki.can-nx.com/en/guides/chart-save/) returns an existing dashboard to the last saved configuration.

## Check the result

After saving, check in the panels of each active meter that the values and units match the expected readings. If [KNX monitoring](https://wiki.can-nx.com/en/guides/chart-monitoring/) is offered, handle it to assign the addresses to the monitoring gateways.

## Troubleshooting

If a Modbus configuration is missing, if a field remains invalid or if saving does not produce the expected result, see [the meter troubleshooting](https://wiki.can-nx.com/en/guides/chart-meter-help/). For an unknown measurement or parameter, contact support@can-nx.com with the project, the dashboard and the field label, without an access key.