Extract from the 11.2 online help (and also future 12) :
What you need to know when running PcVue as a Windows service :
Only one instance of the Supervisor process can be executed at a time. You cannot start another instance of the Supervisor if one is already running on the same computer.
Signify that you cannot start RDS sessions and PcVue as a service on the same computer.
The advise architecture is :
Server 1 can run as service
The usage of Firedaemon (or equivalent tools) is now obsolete and blocked.



