Question about C programming for FSX data capturer

[DesertStorm]

Hi all! It's my first time in this forum, I'm Dani, aerospace engineer from Spain and a general aviation cockpit builder using IOcards. My apologies if my English is not good.

I'm trying to make a little data capturer written in C in order to gather some data from FSX and I'm having some issues with some offsets. I'm following the C example of the SDK, but I think not all the offsets works in the same way and is the cause I'm not getting the correct values.

If I try to get size 1 variables, for example "fuel pump", "pitot heat", etc, I get the correct values: no problems.

 

But if the sizes are greater than 1, I can't obtain any reasonable value. Normally I obtained a mix of positive and negative values. I will put an example of what I'm doing, if its helpful:

In this code I'm trying to get the "0 to 16383" range of flaps. But I obtained for the FSX cessna 172, the following values: 0, 85, -86, -1 for each of the 4 positions.

Same happens with the gear trim and for all of diferent than 1 byte size variables, All what I obtain is random values with no sense.

I suppose I'm doing something terribly wrong but I have tried not to get away a lot of the C example of the SDK, more or less is the same structure (I added the 25 times bucle).

 

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "FSUIPC_User.h"

int main()
{
	DWORD dwResult;

	if (FSUIPC_Open(SIM_ANY, &dwResult))
	{
		char flaps[4];
		BOOL allOk = TRUE;
      
		int n = 0;
		while (n<25)
		{
			if (!FSUIPC_Read(0x0BDC, 4, flaps, &dwResult) ||

			!FSUIPC_Process(&dwResult))
			{
				allOk = FALSE;
			}

			if (allOk)
			{
				printf("Flaps = %d\n", flaps[0]);
			}

			Sleep(100);
			n++;
		}
	}
}

 

I have tried also to read using flaps [1], [2], and [3] but with worst results, because in the C example of the SDK you read [0] [1] and [2] to obtain hours minutes and seconds. Also I tried to use %s instead %d, and so many combinations.

Can you please provide any extra information of what I'm doing wrong to try to better understand the working of the C FSUIPC programming? My goal will be to obtain the values that comes on the offset status pdf, to after convert it to engineer values as I do in my work with ARINC protocols in real planes.

Thanks!

Dani

 

[John Dowson]

Hi Dani,

as the value is a 4 byte integer, try defining

   int flaps;

and

if (!FSUIPC_Read(0x0BDC, 4, &flaps, &dwResult)...

...

printf("Flaps = %d\n", flaps);

 

John

 

P.S. For flaps position, you probably want offsets 0BE0 and 0BE4.

[DesertStorm]

Thankyou very much, I thought that fsuipc_read() only admitted char as a input, It works now!

Again thankyou!

Regards,

Dani

[John Dowson]

It accepts a memory address, with the size as the second parameter (also offset size). You should define it to be the type you are actually reading.
You should also maybe check-out Paul Henty's client dll for .net / c#, as this provides a higher level abstraction that many folks find easier to use (although its for c#).
See https://forum.simflight.com/forum/167-fsuipc-client-dll-for-net/

Regards,

John