FSUIPC is effectively a successor to FS6IPC.dll. Both modules are designed to allow external (i.e. separate) programs to communicate with and perhaps control Microsoft Flight Simulator. It seems some folks are rather confused about what this means, so I should emphasise here that Flight Simulator Panels (including their Gauges), Aircraft, Scenery and other graphics, and pretty much everything else within Flight Simulator, are mostly NOT correctable or influenced in any way by FSUIPC. Apart from some assistance in providing weather data to adventures, making adjustments in the weather itself, and enabling better access to some engine variables for some Gauges, FSUIPC can only help external applications talk to FS, nothing more.
Some FS applications that may seem to be separate applications are, in fact, not: FSNav, WidevieW, FSAssist and FSTraffic are examples of applications for FS that are ‘added-in’ rather than ‘added-on’ and do not use the external FS6IPC interface.
With effect from Version 2, FSUIPC will also work within Microsoft Combat Flight Simulator. With CFS2 it provides access to many of the things that programs enjoy on FS2000 and FS2002, including full weather control. However, it should be noted that CFS2 is not the main target, and support for 100% of the features is not guaranteed. With the original Combat Flight Simulator (“CFS1”) the features are much more restricted: for instance there are no operating weather facilities in FSUIPC for CFS1. FSUIPC will not work with CFS3. There is no place for add-in programs at all in CFS3.
Whilst FSUIPC can be used in FS98 in place of FS6IPC, for most users there is no particular benefit in doing so. WideFS users will want to, as will any users of those more recent applications that specifically depend on FSUIPC rather than FS6IPC. Also, application developers may wish to use the IPC logging facilities, which are still provided in FS98 (but controlled only via the INI file).