I need to find out if it's compatible as a surface controller for Sonar X-3 and if so what the procedure is for set up.

I have one and it works right with Cakewalk Sonar Artist on Windows 10 x64. There is just an issue that at first start Windows 10 doesn't recognize the surface controller/interface so a restart is needed. I have not managed to fix that.

Despite that nuance (having to restart my PC after the first boot up), there is no issue I have found using this surface controller.

I just found Sonar mode on the setup at Aux 4 when firing up the system. I didn't see it yeserday so I'll try it and cross my fingers. I'll report back thanks for your help.

I use the ProjectMix I/O on Sonar mode.  Again, it works correctly.  I use also with Cubase and it works right with it too.  Just it is sad that, as per ProjectMix manual, some of the surface buttons have no mapping to SONAR and the MTR (meters) display is not available on SONAR neither. 

I finally found the Sonar mode at Aux 4, and have audio working I just haven't figured out the controller setup yet. I haven't used the unit before so it's slow going. 

it works perfectly! projectmix with sonar x3 or with platinum....

Got it up and running like a top. Thanks for your help.

My Project Mix was working great using ASIO now it is not connecting.
Windows recognizes it and the firewire devices says all is OK.
I also noticed that using ASIO the inputs are not Selectable but using WDM they are.
Any Ideas?

I updated from Windows 7 to Windows 10 and my projectmix ist still running fine.
Are you using the latest drivers? I think it is the Win7 driver.
Can you open the projectmix-panel from the taskbar?
What kind of firewire-card do you use? It´s always the best to use a card with texas-instruments chipset.
And you have to use the legacy-firewire-drivers in windows.

I've been using WDM and it's working fine for me and I haven't tried ASIO. I ran into problems trying to get the unit interfacing with Sonar in the beginning then out of the blue it worked perfectly and don't know what caused it. I have had a glitch or two from time to time, usually it seems the problem stems from not having the Projectmix turned on when I turn on the computer, a reboot with it turned on remedies the problem. I may at that point have to reassign output in the PC control panel.