The functional group Sonos Playbar can be used for controlling functions Play, Pause, Mute and Volume of the Sonos Wi-Fi loudspeakers of a multi-room system.
Click the Avio Services icon 
and select Functional Groups. In the dialog popping up click Sonos Playbar to enable this functional group which will then be listed in yellow at the top. Finish by clicking Apply Changes.
Click on the Avio Service icon again and select Configure Sonos Playbar...(enabled) and enter IP address and port of the loudspeakers to be controlled as shown in the example below:
192.168.122.44:1400;192.168.122.45:1400;192.168.122.46:1400
IP address and port are separated by a colon; entries for the next loudspeaker are separated by semicolons.
The Avio start port is preset and usually does not need to be changed. Close the dialog by clicking Save.
When you open Avio Manager you will find a folder Sonos Soundbars with the IP address in brackets, e.g.Sonos Soundbars (192.168.122.44) for every loudspeaker listed in the Avio Service for your PC.
The folder contains the channels Play, Pause, Mute, Current Volume and Set Volume, which can be linked up with other channels and controlled. See also Connecting and editing channels.