I'm looking at building some hardware components to interface with Microsoft Flight Simulator which (hopefully) will display things that are currently taking up screen real estate (altimeter, airspeed indicator, radios, etc.)
Is there a way to read the values they have while FlightSim is running so that I can synchronize the external, hardware components with what they should be on screen? Preferably relatively quickly so there isn't much lag.
This link may provide some insight into the MS Flight Simulator API (SimConnect ): http://msdn.microsoft.com/en-us/library/cc526983.aspx
Specifically, here is an article on Monitoring AI Objects: http://msdn.microsoft.com/en-us/library/cc974114.aspx
Have a look at Project Magenta
With several thousand installations to date, from desk-top systems to approved flight training devices, Project Magenta has become a very recognizable name in flight simulation. Our products span from type-specific glass cockpits, flight management systems and interfacting software to data logging and traditional IFR training software.
This project use a interface module called FSUIPC
FSUIPC4 is an add-in for Microsoft Flight Simulator X which provides an interface for other programs to read and write all sorts of pertinent data relating to the simulation, and in many ways even to control the actual process itself.
Look at the MS SimConnect API:
http://www.fs-seine-75.com/SDK/Core%20Utilities%20Kit/SimConnect%20SDK/SimConnect.htm
My experience is that SimConnect is a bit problematic if not only for FSX. I believe your efforts would be better directed towards one of the FSUIPC libraries which would give you interoperability with all Microsoft Flight Simulator versions AND Prepar3D.
