Altitude bug with application on MSFS live weather

[FlyingCoder]

I'm making my own ACARS. During testing, i realised that my application using FSUIPC altitude when using live weather is not the same as not using live weather. Cruising at FL230 with live weather, will not detect at im FL230. While, when i off the live weather, the altitude at my planes goes 1000ft up. Is this MSFS issue or FSUIPC issue?

[Paul Henty]

Check which altitude you are reading. FSUIPC offers a few different offsets, giving different altitudes . e.g.:

The actual altitude is given by offsets 0x6020 and 0x0570.

The indicated altitude (i.e. what the altimeter in the aircraft is showing) is found at 0x3324. This reading is dependent on the barometer setting in the aircraft. Below 18,000ft the player should set this to the local air pressure as set by the weather. Above 18,000ft the player should set this to standard pressure (1013mb or 29.92inHG). 

You need to know which one your application is reading and what your altimeter in the aircraft is showing (i.e. what pressure is set). 

You're likely seeing a problem because you're either mixing up the two values, or the altimeter in the aircraft is showing the wrong altitude because the barometer is not set to the correct pressure.

If you don't use any weather the default air pressure is 1013mb which is also the default setting on the barometer. You won't see any problems until you use weather which changes the local air pressure.

Paul