offset for cabin altitude in FSX

[dazzan]

Hi Pete

I am looking for an offset for the cabin altitude (and its format) in FSX.

I was looking through the documentation, but could not find

any information about a cabin altitude offset.

Many thanks for helping

Gilles

[Pete Dowson]

I am looking for an offset for the cabin altitude (and its format) in FSX.

I was looking through the documentation, but could not find

any information about a cabin altitude offset.

Is the cabin pressure simulated in FSX? What do you want to do with it?

The current version of FSUIP4 for FSX is almost as complete in terms of the data accessible as FSUPC3 was/is for FS2004, but it still isn't 100% there because of some shortfalls in what SimConnect provides. There are some additions, where useful-looking data was working and esily fitted in, but on the whole the main aim of FSUIPC4, in terms of its provisions for add-on applications, was to achieve 100% compatibility with previous versions of FS, mainly FS2004.

I would have assumed that new applications, taking advanttage of new features in FSX over and beyond FS2004, would be utilising the interface Microsoft are providing -- i.e. SimConnect.

Anyway, looking at the SimConnect list of variables said to be available, I do see these:

PRESSURIZATION CABIN ALTITUDE
The current altitude of the cabin pressurization.. Feet 

PRESSURIZATION CABIN ALTITUDE GOAL
The set altitude of the cabin pressurization. Feet 

PRESSURIZATION CABIN ALTITUDE RATE
The rate at which cabin pressurization changes. Feet per second  

PRESSURIZATION PRESSURE DIFFERENTIAL
The difference in pressure between the set altitude pressurization and the current pressurization. Pounds per square foot  

PRESSURIZATION DUMP SWITCH
True if the cabin pressurization dump switch is on. Bool 

There are also these controls for changing things -- These are listed in the assignments drop-downs in FSUIPC4's Keys and Buttons tabs already, and you will also find them in the List of Controls installed with FSUIPC4.

PRESSURIZATION_PRESSURE_ALT_INC
PRESSURIZATION_PRESSURE_ALT_DEC
PRESSURIZATION_CLIMB_RATE_INC
PRESSURIZATION_CLIMB_RATE_DEC
PRESSURIZATION_PRESSURE_DUMP_SWITCH

You can of course send via FSUIPC4 these using the numerical equivalents as listed, via Offset 3110.

Are these what you need? Do they work? Can you tell me anything about what you want to do so I can understand what needs providing?

There are many, many new variables listed in the SimConnect documentation, and I really wouldn't know what to do with most of the new ones, nor whether they work or have any use. I can fairly easily add access to these via new offsets in FSUIPC4 if they are wanted, but I really think I should do this on the basis of need rather than add them all just because they are there. There could be a performance impact, and maintaining values which no one ever use and which may not even work is pointless.

So, before adding anything new I'd like the details of what is needed explained, and why, with any details I may need for writing them up in the Offsets Guide documentation.

If you do this, I will certainly look at adding the data to the next FSUIPC4 release. Unfortunately I am on holiday from the end of next week for just over two weeks, so there could be a delay, though I may be able to slip them into an earlier interim version for you to test.

Regards

Pete

[dazzan]

Hi

I would like to use a Goflight GF45 module

together with FSUIPC and gfdisplay to display the cabin altitude

and climb rate.

I also would like to use the knobs on the Goflight module to set

the final cabin altitude and landing altitude.

Many thanks

Gilles

[Pete Dowson]

I would like to use a Goflight GF45 module

together with FSUIPC and gfdisplay to display the cabin altitude

and climb rate.

So they do actually do something in FSX? Which aircraft, the 738 and the Airbus? I'll have to have a look.

I also would like to use the knobs on the Goflight module to set

the final cabin altitude and landing altitude.

You should be able to do that now by simply assigning the controls I mentioned appropriately.

Regards

Pete

Many thanks

Gilles

[dazzan]

I am using the 737-800

[Pete Dowson]

I am using the 737-800

Well, I'm sending you FSUIPC 4.071, which has these additions:

0318 4 Pressurisation cabin altitude at present (feet, 32-bit integer) 031C 4 Pressurisation cabin altitude set goal (feet, 32-bit integer) 0320 4 Pressurisation cabin altitude set change rate (feet/sec, 32-bit floating point)

0324 4 Pressurisation cabin pressure differential (lbs/sq.ft, 32-bit floating point): set – actual.

0328 4 Pressurisation dump switch (1 = open, 0 = closed)

but I can't see much here working correctly. Where are you looking on that awful FSX 738 overhead? The dials which should record these things don't appear to work.

The cabin altitude target (031C) changes by some amount on each INC/DEC control, so that "works", but the cabin altitude sems to simply decrease slowly until, in my case , it reached -89 feet, and never changed even with the dump switch set to open (when it should show the aircraft altitude).

Worse, the change rate doesn't appear to change with the correct INC/DEC controls, and the differential is definitely wrong.

Please, can you explain what you see working, and where? Or are you just being rather over-expectant of what Microsoft have achieved in the initial FSX release?

Regards

Pete

[dazzan]

Hi Pete

Does for example 0318 4 mean

offset 0318 bit 4.

Another question I have is with gfdisplay.

I went through the documentation, but did not find how to

display 0318 bit 4 for example.

I use gfdisplay already for a long time but never had to

define an offset with a bit setting.

Perhaps you have a hint for me.

Many thanks

Gilles

[Pete Dowson]

Does for example 0318 4 mean

offset 0318 bit 4.

No, certainly not! How could it be possible to store an altitude in feet in only one bit? One bit can only represent a 0 or a 1. What would that tell you?

I'm sorry, but I must have misunderstood your original question. When you said you couldn't find the offset I thought you must have looked at the list of offsets for FSXdidn't you? If not, where were you looking?

If you look at the list of offsets, do you not see that the second column shows the number of bytes in the value documented? In this case, because the value is a 32-bit integer, as it says, it occupies 4 bytes (4 x 8 = 32).

I went through the documentation, but did not find how to

display 0318 bit 4 for example.

If you want to display just one bit (though why you'd want to I don't know) you need to extract that bit using a logical "and" operation, with a Mask. The mask for bit 4 is 2^4 which is 2x2x2x2, which is 16.

I use gfdisplay already for a long time but never had to

define an offset with a bit setting.

Perhaps you have a hint for me.

Well, I'd like to understand how you thought that a number of feet could be displayed by showing one bit? ;-)

Where are you looking for offfsets? It is rather worrying that you may be using a source which I cannot keep updated. :-(

Regards

Pete

[dazzan]

Hi

I was looking for the offsetes in FSUIPC 407 SDK.

But I am sorry I did not remember that the second columns were bytes.

You understood my initial question perfectly, thanks.

Thanks

Gilles