Modbus

Weather stations and sensors for temperature, humidity, CO2, dew point, filling level.

Modbus in building automation is a widely used communication protocol that enables the exchange of data between different devices and systems within a building, similar to KNX, DALI and BACnet. Modbus is considered simple, reliable and flexible and is used to control and monitor heating, ventilation and air conditioning (HVAC) systems, lighting systems, blinds, energy management systems and security solutions. Modbus is a cost-effective solution as it is an open standard with no licence fees and is supported by many manufacturers, offering a wide range of different Modbus devices.

Modbus is based on a client-server model, whereby the client initiates the communication and the servers respond to it.

The implementation and maintenance of Modbus systems is simple, fast and cost-effective, as Modbus is characterised by a clear and simple communication protocol structure. The decades of use and the resulting optimisation of the system, its robustness and the proven and stable technology also contribute to the popularity of Modbus technology.

Yes, there are four different types of Modbus that are used in building automation, depending on the application. Our devices support Modbus RTU, the most common and most robust variant:

Modbus RTU (Remote Terminal Unit)

Modbus RTU uses serial communication via interfaces such as RS-232 or RS-485 and transmits data in an efficient binary format. This variant is particularly suitable for applications where reliability and stability on slower communication channels are paramount. Due to its robustness and widespread use, Modbus RTU is the first choice in many building automation and industrial applications - and is also supported by our devices.

Modbus ASCII

Modbus ASCII is also based on serial communication, but transmits data in readable ASCII format. This makes debugging easier, but results in lower efficiency and speed. This is why Modbus ASCII is rarely used in modern applications.

Modbus TCP/IP (Transmission Control Protocol/Internet Protocol)

Modbus TCP/IP utilises Ethernet networks for data transmission and offers higher speeds and greater ranges. It is often used in modern, more complex networks, especially when a large number of devices need to be integrated.

Modbus Plus

Modbus Plus is a proprietary high-speed network from Schneider Electric. It is less common because it is designed for specialised applications and does not offer the open structure of other Modbus variants.

With our support for Modbus RTU, you get a proven and reliable solution that is ideal for a wide range of building automation tasks.

Modbus was developed in 1979 by Modicon (now part of Schneider Electric) and has since established itself as one of the most widely used communication protocols in industrial and building automation. Modbus RTU, one of the oldest and most robust variants, plays a central role and is a proven standard for numerous applications in building automation.

Modbus RTU is based on serial communication via interfaces such as RS-232 or RS-485 and transmits data in binary format. It is often used to connect devices reliably and stably. Typical applications are

• Heating, ventilation and air conditioning (HVAC) systems: Modbus RTU enables the networking of sensors, controllers and actuators for the precise regulation of temperature, humidity and air quality.
• Lighting systems: Complex lighting control systems, such as zone-based or dimmable lighting, can be operated efficiently with Modbus RTU.
• Energy systems: Energy meters, inverters or battery systems can be monitored and controlled to optimise energy consumption.
• Security and access systems: Modbus RTU is used to connect alarm systems and access control solutions, ensuring stable communication.

Its robust architecture and widespread use make Modbus RTU a favoured choice in building automation. Especially in environments where reliability and stability are crucial, Modbus RTU has proven itself over decades. It provides a proven basis for controlling and monitoring numerous building technology systems and remains a mainstay of the building automation industry.

Modbus can be implemented in numerous applications, e.g. it can be used to monitor and control HVAC systems, lighting and energy consumption. Modbus is also commonly used in industrial automation, e.g. for controlling production systems or monitoring sensors and actuators. Modbus is also used for remote monitoring and control of plants and systems, e.g. in remote areas.

In building automation, Modbus can be used, for example, to control and monitor heating and cooling systems or to regulate room temperature, humidity and air flow.

Lighting control can also be implemented with Modbus, e.g. lighting systems can be remotely controlled or completely automated. You can also use Modbus to adjust the light intensity and time control to save energy and increase comfort.

You can also use Modbus to control your blinds and roller blinds in order to realise the most effective sun protection possible. Modbus can also be integrated into daylight control systems to achieve improved energy efficiency.

In addition to controlling building automation, you can use Modbus to control and monitor security applications, such as alarm systems, access control and surveillance cameras.

Modbus is often combined in buildings with other bus systems such as KNX, DALI or BACnet.

Modbus and KNX are two important communication protocols in building automation that differ significantly in terms of structure, functionality and possible applications.

Modbus is a simple, serial protocol that is often used in industrial automation. It is based on a client-server architecture in which a central client retrieves data from several servers or sends commands. Modbus supports various physical transmission types such as RS-485, RS-232 and TCP/IP and therefore offers a high degree of flexibility when connecting devices. Communication usually takes place via register queries and write processes, which limits data exchange to simple control commands or measured values.

KNX, on the other hand, has been specially developed for building automation and follows a decentralised approach: each device can send and receive commands independently without the need for a central client. KNX supports twisted pair cabling (TP) as well as IP, powerline (PL) and RF (radio), which offers a wide range of installation options. KNX allows the integration and control of complex systems such as lighting, heating, ventilation and blinds, whereby data transmission is highly efficient and interoperable thanks to a standardised telegram format. Thanks to numerous standardised interfaces to other systems such as DALI, Matter, BACnet, Modbus, Ethernet, M-Bus, SMI, EnOcean etc., KNX is extremely flexible for use in buildings.

To summarise, Modbus is particularly suitable for the simple and cost-effective connection of industrial devices, while KNX is the preferred choice for networked and highly integrated building automation solutions.