---
title: "KNX and Modbus water metering: track consumption with Chart’nX"
description: "Track water consumption with Chart’nX: KNX or Modbus meters, primary and secondary meter groups, calculated differences and presence overlay."
canonical: https://wiki.can-nx.com/en/usages/eau/
language: en
---

# KNX and Modbus water metering: track consumption with Chart’nX

Chart’nX tracks a building’s water consumption in a dedicated dashboard. Each measured meter reads its value from a KNX group address or a Modbus configuration, in liters, kiloliters or cubic meters. The form offers a total meter and groups, each made of a primary meter and its secondary meters, with calculated sums or differences. Presence can also be overlaid on consumption.

## Solutions for your need

| Need | Application | Guide |
| --- | --- | --- |
| Name the dashboard and configure the total water meter | Chart’nX, **General** and **Main meters** | [Configure the general information and the total meter](https://wiki.can-nx.com/en/guides/chart-water-general/) |
| Overlay presence on a meter’s consumption | Chart’nX, **Overlays**, **Presence / absence** source, then **+ Add overlay** on the meter | [Configure the general information and the total meter](https://wiki.can-nx.com/en/guides/chart-water-general/) |
| Group a primary meter and its secondary meters | Chart’nX, **Sub-meters**, **+ New group** | [Add a group and its water meters](https://wiki.can-nx.com/en/guides/chart-water-groups/) |
| Calculate a sum or a difference between the meters of a group | Chart’nX, **Operations** protocol | [Compose a water calculation](https://wiki.can-nx.com/en/guides/chart-water-operations/) |
| Add several Modbus meters from the catalog to a group | Chart’nX, **Import modbus** in the group header | [Import Modbus configurations](https://wiki.can-nx.com/en/guides/chart-modbus-import/) |
| Choose the colors and card order, duplicate or remove a meter | Chart’nX, group cards and **Display order** | [Organize the cards of a water dashboard](https://wiki.can-nx.com/en/guides/chart-water-layout/) |
| Clear a blockage: save refused, presence missing, inconsistent volume | Chart’nX | [Troubleshoot a water dashboard](https://wiki.can-nx.com/en/guides/chart-water-help/) |

The water dashboard opens from the **Chart'nX** section of Emergy’nX, then **Configure** ([access from Emergy’nX](https://wiki.can-nx.com/en/guides/chart-open-emergy/)). In this flow, **New dashboard** creates an energy dashboard: if your project has no water dashboard, contact support. For a Modbus meter missing from the catalog, [declare its configuration](https://wiki.can-nx.com/en/guides/chart-modbus-config/), then [test a reading](https://wiki.can-nx.com/en/guides/chart-modbus-test/). After saving, handle [KNX monitoring](https://wiki.can-nx.com/en/guides/chart-monitoring/) if it is offered.

## Good to know

- Each meter of a group, primary included, declares the unit it actually receives: **Liter (L)**, **Kiloliter (kL)** or **Cubic meter (m³)**. A group can mix these units: Chart’nX converts the values to liters before combining them.
- **Index** suits a cumulative reading, **Not indexed** a value that already represents the period or the instant. The non-zero **Custom Factor** starts at 1; it corrects the metering ratio, not the unit.
- A **Real** primary is a dedicated measurement; a **Virtual (∑ secondaries)** primary is the sum of the group’s secondaries and requires at least one secondary.
- The presence source is read over KNX or Modbus. Over KNX, its **Group address** uses the three-level format, for example the fictitious **1/2/3**. In **High / low state**, the **Present** row states whether 1 or 0 means presence.
- Removing a group takes it out of the form without confirmation. Until the dashboard is saved, **Cancel** in the save bar returns to the last saved configuration.
- For a volume that looks wrong, first check [the period and precision](https://wiki.can-nx.com/en/guides/chart-period/). A gap between the primary and the sum of the secondaries is not enough to conclude there is a leak.

For electrical energy, see [Energy and metering](https://wiki.can-nx.com/en/usages/energie/); for gateways and registers, [Modbus](https://wiki.can-nx.com/en/protocoles/modbus/).

## All Water metering guides

### Configuration and use

- [Set up a Chart’nX water dashboard: name, presence and total meter](https://wiki.can-nx.com/en/guides/chart-water-general/)
- [Create a Chart’nX water meter group: primary and secondary meters](https://wiki.can-nx.com/en/guides/chart-water-groups/)
- [Organize, duplicate or remove the cards of a Chart’nX water dashboard](https://wiki.can-nx.com/en/guides/chart-water-layout/)
- [Calculate a sum or difference of water meters in Chart’nX](https://wiki.can-nx.com/en/guides/chart-water-operations/)

### Questions and troubleshooting

- [Chart’nX water dashboard: troubleshooting and frequently asked questions](https://wiki.can-nx.com/en/guides/chart-water-help/)