R091 is the follower of successful converters R090 and M090. This device, which acts as a Modbus TCP server, controls a DALI (Digital Addressable Light Interface) bus which may host up to 64 DALI ballast controllers. The R091 is a multimaster with collision avoidance/detection at the DALI bus (EN 60929 ed. 4:2011 Annex E). It also provides a detachable bus power supply.

The Modbus table was enhanced by sections providing data on telegrams coming from DALI sensors and switches (input devices). There is 8 more blocks which are able to send telegrams 8, 16, 24, or 25 bits long,

which enables communication with non-standard devices.

The converter offers a web interface for manual entering of some DALI commands including bus configura- tion and diagnostic commands. The R091 fully covers the functionality of R090 and M090. As some of the use cases need more explanation, the data sheet includes several examples with description of the command setup.