Please first uninstall any Eucon software you have installed. After the uninstall process, check that you have no more Euphonix folders in C:/Program Files and in C: /Program Files(x86).
Please make sure you install the 64 bit version of Eucon 2.6.2, and make sure you use Pyramix 8.1.9, 8.1.10 or 8.1.11.
When you have installed the 64 bits version of Eucon, make sure that in c:/Program Files(x86)/Common Files/Merging Technologies/Controllers, the file version of MTOASISTransportEucon.dll is the same as your Pyramix version.
You can download the correct version here :
Pyramix 8.1.9 :http://download.merging.com/beta/Suppor
Pyramix 8.1.10 or 8.1.11 :http://download.merging.com/beta/Suppor
Reboot your computer
Make sure you see your Artist controller in EuControl.
Start Pyramix and go in Settings > Controller > Add / Driver : Oasis - Transport : EUCON.
If you still have the "Unknown Protocol" issue, please close pyramix.
Go in C:/Windows and launch Regedit.exe
In the left pane, browse to HKEY LOCAL MACHINE > Software > Merging Technologies > Pyramix > Controllers list > OASIS Transport list.
Select EUCON in the right panel and press F2 to rename it. Enter anything for the name, enter.
Then press F2 again and this time name it "EuCon". (For Windows registry EUCON and EuCon are the same value, that is why you cannot rename it directly to Eucon).
Now restart Pyramix, you should no longer have the unknown protocol error message.