Awesome, thanks Craig!
Ok, just got around to doing a fresh install of OH3. I dropped the jar into the addons folder, and have the serial binding installed. The device does not show up. It has been so long since i messed with these setups, and will continue to. But if any other tips on what i might be missing, happy to hear.
Update- looks like it got it. had to add zones not device
Thats weird. I add the RNet device and fill out the # of units and zones per device and it creates the zones automatically and they show up in inbox. If you don’t have a device I’m not sure how it would have the connection info to the main russound amp.
Mostly just chiming in to say thanks for the binding.
Recently bought an MCA-C3 and a CAV6.6, and also may be integrating a Vaux Lattis switch into openhab as well.
After a firmware update/reset the C3 is recognized. All zones and sources appear in the inbox with the names given to them via the SCS-C5 software.
Haven’t tried the CAV yet, looks like it might work with this binding(?), or else might have to be a serial device like the Vaux, which I did get to respond to serial commands from my pc. 
Anyone tried the binding with OH 4?
I use it with OH4 with no issues.