In order to use PACX with Microsoft Flight Simulator (MSFS 2020), FSUIPC 7 is required. FSUIPC 7 is a utility that allows applications to connect to and interact with various simulator platforms. It is not developed, maintained, or sold by TFDi Design.
FSUIPC 7 is available as a free download from here. Please note that you may be prompted to enter a registration code during installation. This is not required and can be skipped, but if you are so inclined, we do recommend you support the FSUIPC developers by purchasing a registration key.
Once downloaded, extract the contents of the zip file and run the installer. When you ready to fly open FSUIPC7.exe, then open your simulator from the installation directory you selected. This will allow PACX to communicate properly with your simulator.
Please note: this article applies only to Microsoft Flight Simulator (released in 2020), not to Flight Simulator 2004 or Flight Simulator X. PACX automatically installs the required dependencies for other platforms upon first run.