How to use the M-Bus Scan ?

This article explains how to use M-Bus Scan.

General Information on the M-Bus Protocol

M-Bus (Meter-Bus) is a communication bus that allows data exchange between the Wattsense Box and your devices. It is a wired network that allows you to connect devices that may be physically distant.

The master unit (Wattsense Box) powers the bus and provides a DC voltage of 37 V. The Wattsense Box can natively handle 3.6 mA (3 x Units) on the bus.

If you wish to scan/communicate with more than 3 devices, you must use an M-Bus repeater.

To connect one or more devices:

• Connect the M-Bus device to the M-Bus port on the Box.
• Each M-Bus device must follow the following connection:

Hardware Installation

Make sure that wiring is correct:

• The polarity is correct.
• Make sure the bus is powered only by the box (approximately 37 V).
• All devices have the same network configuration (baud rate, unique M-bus address, etc.).
• The communication cables are twisted pairs.
• Make sure your topology respects this polarity.

Addressing System

The M-Bus protocol allows two addressing modes: primary addressing and secondary addressing.

Primary addressing: Each device (e.g., a water meter) is configured with a unique address on the M-Bus network. This address is a value between 1 and 250.

Secondary addressing: Each device has a unique address. This identifier is 16 characters long and consists of four fields (Manufacturer, Serial Number, Version, and Device Type). This addressing system allows communication with meters without the need to configure a fixed primary address.

Configuration example

Implementation

Step 1

Go to the Configuration tab and add a new equipment.

Then select the Scan an M-Bus network button.

Select the baud rate of your M-bus network.

The common baud rate is 2400 bauds. Most meters use baud rates of 300, 2400, and 9600.

Step 2

If a previous scan was detected, it can be used to select properties. Otherwise, click the Request new Scan button:

Restart a scan

The next window asks you to specify the addressing mode and the target address range.

You can choose:

Primary address: all devices on the M-Bus network (full network scan) or scan only devices within a given address range (e.g., between 1 and 10). In this second option, all devices not within this range will be ignored by the scan.

Secondary address: all devices on the M-Bus network (full network scan) or filter devices using a mask based on the ID number.

Once you have chosen your addressing system, click Lauch the Scan.

The analysis time may take more than 6 minutes, depending on the number of equipments on the bus and the baud rate.

Step 3

The next screen has several sections:

1. On the left, you can search for a specific piece of equipment.
2. The list of equipment found during the scan is located in the bottom left corner. Click on a piece of equipment to display the list of discovered properties.
3. The list of equipment properties is displayed on the right side of the screen.

Select the data points you want to monitor.

For your information, two columns, dib and vib, appear in the properties list.

• The DIB (or Data Information Block) describes the nature of the data that follows. For example, it indicates the data type (integer, float, text, etc.), the data length, etc.
• The VIB (or Value Information Block) complements the DIB by providing information about the unit and meaning of the value: the unit of measurement (liters, kWh, °C, etc.), the scale (multiplier, such as x10, x0.1, etc.), etc.

Advanced Scan

If you receive the following message during the scan phase:

The scan may still be in progress. This can happen if the number of M-Bus devices is high and/or if the communication speed is low (2400 baud in our example). In this case, you can check the scan progress in the Configuration / Networks / Scan button menu on the M-BUS network line:

In this example, the scan progress is not finished (10%)

Please contact us if you need any additional information : Wattsense Support