The eBUS is a two-wire serial communication interface used in heating and solar energy appliances.
Some eBUS converters are very expensive, others are not. So I tried to build my own one.
The eBUS converter is bus powered. Voltage regulator is a LM1117-5.0V. On the right side of the schematic you have to set the voltage input level with the resistor R4. The output with the label RXD can directly connected to USB to Serial (TTL) adapter. The transmit part is currently not tested.
Orginal schematic is available from eBUS-wiki.
More information on Wikipedia.