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eBus is an interface protocol used in heating technology , which is based on the serial interface technology RS232 in twisted pair technology with two wires. It was introduced by the Dungs company. 2400 baud are used and the respective binary signal levels are:

  • logical 1: nominal 15 V (15–24 V)
  • logic 0: 9-12 V

The bus system is multi-master capable with up to max. 25 masters and 228 slaves , so a maximum of 253 participants.

8 bits and a stop bit are used. The individual connected devices can draw up to 18 mA of current from the network. It is used in particular in the area of ​​heating and solar systems .

Physical layer

The eBus has a fixed baud rate of 2400 baud +/- 1.2% tolerance. The eBus is a LOW-active bus with the following levels:

Level Channel receiver
HIGH = 1 > 15V DC > 15V DC ... maximum 24VDC
LOW = 0 <= 10V DC
> = 8V DC
(typically 9V DC)
<= 12 V DC
> = 8 V DC

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