KWB

First of all thanks for the hints. Just to make sure, for my test I use a connection via "WideFS Client", for the code I use the SDK from here: http://www.schiratti.com/dowson.html The info is just to avoid that I use some wrong version or code base Here is where it fails in read, I have just placed a single line for test purposes in my read function. I open in my object's connect function, then I call my read function: FSUIPC_Read(0x0238, 3, localFsTimeRaw, &dwResult); ==> calls if (!m_pView) { *pdwResult = FSUIPC_ERR_NOTOPEN; <-- returns this value return FALSE; } Now I did a second test and try to open just before, then failing with FSUIPC_ERR_MAP, so this means m_pView is 0, but the connection still exists. No idea how I can get into that status. FSUIPC_Open(SIM_ANY, &dwResult); <== fails with ERR_MAP FSUIPC_Read(0x0238, 3, localFsTimeRaw, &dwResult); if ((m_hMap == 0) || (GetLastError() == ERROR_ALREADY_EXISTS)) { *pdwResult = FSUIPC_ERR_MAP; FSUIPC_Close(); 3rd version, I just close before I reopen and read. Everything works, even with my FSUIPC_Close(); FSUIPC_Open(SIM_ANY, &dwResult); FSUIPC_Read(0x0238, 3, localFsTimeRaw, &dwResult); Now my naive conclusion, my connection seems to get broken somewhere. If it was closed somewhere, example 2 would work. So somehow m_piew is 0, but still something is open. I am using an "all compiled" version, no libs. Compiling with VS2017, in this very case 32bit. Maybe there is any hint, but however expect this is some odd detail.

Question: What is the scope of an FSUIPC_Open? Hint: Using the C version of FSUIPC SDK with FSX: FSUIPC 4.9.7.3 (FSX) 32 bit, my full code is attached as file. I have a small class wrapping my FSUIPC functionality. The FSUIPC_Open itself works (returns true, DWORD result is 0) I can also FSUIPC_READ in the same function, so far so good. bool CFsuipc::connect(bool force) { .... DWORD result; ... if (FSUIPC_Open(SIM_ANY, &result)) ... Now in another function (read) I rely on that opened FSUIPC connection. Still the same object in memory. bool CFsuipc::read(CSimulatedAircraft &aircraft, bool cockpit, bool situation, bool aircraftParts) { if ( FSUIPC_Read(0x0238, 3, localFsTimeRaw, &dwResult) && Now the read fails with "FSUIPC read error 'Call cannot execute, link not Open'` So somehow my open connection got lost. I can say for sure, the object is still the same. So where is the info of the open connection stored? Of course I could always open in the same step as I read, but I wonder why the state of the connection does not persist? fsuipcimpl.cpp

Cool. Just to confirm the above, we are using also just a single point grid.

I can not exactly say, but there are already question about the function back in 2012: http://prepar3d.com/forum/viewtopic.php?t=7290

On P3D there is a function for that (SimConnect_RequestGroundInfo, not compatible with FSX), new P3D API. For FSX I create a bogus AI object and query the position at its position (kind of hack but working). For the later I still search a way to create an invisible AI object https://www.fsdeveloper.com/forum/threads/invisible-or-very-small-ai-object.442575/

Moved to Main Forum. Please ask questions related to FSUIPC always in Main Forum! Is there a way to get the ground elevation for a given latitude/longitude position. I need to get the current ground elevation (representing the scenery) at a given position, which is NOT my own aircraft's position and NOT the position of another AI aircraft. I know how to do it with FSX and P3d/simConnect, but need a similar function for FS9. Any hint how I can do it (if possible)?