Offset 0x3324 question

[robvanderwiele]

Hello Peter,

I got a question about calculating the value you provide in offset 0x3324. When I use offset 3324 in my 737NG Glass software I'm working on, it updates rather slow. When I make a climbing turn the heading rose keeps turning smooth but the alt tape (which uses offset 0x3324) has hickups. The tape stops for a moment and then continues again. So I changed the offset it uses to 0x0570 or 0x6020. Now the hickups are gone but these offsets don't take the pressure difference of the QNH and the kollsman altitude setting into account. When I try to calculate them from offset 0x0330 and 0x0EC6, I can't get the result from offset 0x3324. I come close but the difference is not always the same. Could be rounding errors, but I don't know for sure. Could you tell me how you calculate this offset and with what offsets please, so I can get rid of those hickups.

Thanks, Rob van der Wiele

Here a picture of the 737NG PFD.

[Pete Dowson]

I got a question about calculating the value you provide in offset 0x3324. When I use offset 3324 in my 737NG Glass software I'm working on, it updates rather slow. When I make a climbing turn the heading rose keeps turning smooth but the alt tape (which uses offset 0x3324) has hickups.

Is this FSUIP3 or FSUIPC4? It should be perfectly smooth in FSUIPC4 (well, as smooth as FSX is) since it is obtained at the FS frame rate.

In FSUIPC3 it is obtained by a call to PANELS.DLL (much as a Gauge would), but because all such calls are an overhead, this is one of a large number which are performed every few FS frames -- 4 I think, in this case. Would that explain your problem?

I have gradually been "promoting" assorted offsets to faster updating, on request. For today's PCs it won't be such a noticeable performance overhead, though I'm not willing to do a wholsale update on them. This is the first request for this one, but I will promote it to every frame with the next increment (probably 3.809 on Monday or Tuesday -- look out for it in the "Other Downloads" announcement above).

Could you tell me how you calculate this offset and with what offsets please, so I can get rid of those hickups.

I don't calculate it, I read FS's own result. I used to compute it, long long ago (version 2.??), but it never exactly equated to FS's computation. I did find out what values they were using once, but I've long forgotten, sorry..

Regards

Pete

[robvanderwiele]

Hello Pete,

Thanks for your quick response, I encounter these hickups with version 3 under FS9. I will check version 4 with FSX. But for now I'm testing under FS9 mostly and sometimes with FSX to see if it is still working for both versions. Would be great if you could make the change in version 3. So it makes sence that I don't get the exact same results as FS does about these calculation. I will check the other downloads next week.

Thanks again, Rob