MobiFlight Community Support

Hi!

I´m trying to install a yaw damper with a servo and mobiflight in my 737 cockpit but it is impossible to find the offset of 737 PMDG for this purpose.

I have read that Yaw damper is equal to turn coordination, and this value appears in FSUIPC table as offset $036E

The problem comes when I try to configure this value with mobiflight as integer 1 bit. The values are from 0 to 256 but it not follow any pattern for its behaviour. For example when the airplane is stopped the value is 0 but when you move forward or turn, the values registered increases with no difference between left and right.

In FSUIPC manual explain that this offset has a value range from -128 to +128 being 0 neutral position, but mobiflight do not show any negative value. I only can see positive values.

What I m doing bad?

Many Thanks!

Regards

Dear Francis,

unfortunately I have not the solution, but I am facing the same problem at the moment and having the same problems with the offset you mentioned above.
I tried several offsets which I found on the project magenta webside marked with "YAW" but none of them work as they should. May be you can try them out too, and please reply here if you have any success.
Furthermore I found this sioc script:

Var 0400, name YD_CENTER, Value 552 // CENTRO INDICADOR - INDICATOR CENTER

Var 0410, name OFS_TURNCOORD, Link FSUIPC_IN, Offset $036E, Length 1, Type 1 // OFFSET OF TURN COORDINATOR BALL
{
L0 = &OFS_TURNCOORD * 2
&YD_SERVOMOTOR = &YD_CENTER + L0
}

Var 0420, name YD_SERVOMOTOR, Link USB_SERVOS, Output 1, PosL 1, PosC 512, PosR 1023 // SERVO YAW DAMPER INDICATOR

But I don t understand how this should work. May be you have an Idea. Please report.

Best regards
Michael

Hi Michael,

I also found the script you mentioned in the opencockpits web, but it is not working, for me.

This script takes the offset value 036E and aply x2 multiplicator, and later add a fixed value of 552. In my opinion it has utility if you receive negative data from the offset and you want to convert it in positive always. For example. FSUIPC manual explain that this offset has a value from -128 to 128. In the worst case, if we receive -128 and multiply x2 we obtain -256 value.

If we add 552 we obtain -256+552 = 296. Positive value. The new range of positive values remain betwen 296 to 808 with a center of 552. The idea is fine, but fails in the implementation.

I think that the problem is because the offset 036E show data without the pattern that is expected from the yaw damper behaviour.

This offset is from FSUIPC and PMDG is "another history" it runs by his own offsets.

Furthermore, after several test with PMDG with no results, I tried to make a fly with a cessna in order to understand better the turn coordination offset and see "what happen" and which would be the problem. I was surprised in one thing.

The turn coordination gauge of the cessna, consist of a pictogram of a plane, or "wing roll" and a ball. This is the problem! I think that we need the offset of the BALL, that under my point of view is the movement of "slipper" that is equal to yaw damper.

The offset that we are using makes refference to "wing roll".

I m probably wrong in my development, but it is all that I have discovered by myself due to lack of information about this gauge.

Regards.

Dear Francis,
it looks like that you are much more experienced in this matter than me.
This issue is discussed since several years even in the avsim pmdg forum.
Obviously even the guys from pmdg havent had a solution.
For example on this side:
http://www.projectmagenta.com/all-fsuipc-offsets/
I found this:
DWord:
0808 4 fsYawDamper
Offset 0×060, 4 bytes, the FS Yaw Damper
But it even doesn´t work for my setup. May be you have a better chance.
There are some more offsets dealing with "Yaw" but most of them didn´t show any output.
I will give it a second chance next sunday.
May be there is a way to get the little bar moving. I will be back here if i have any news.
Please keep me informed when you succeeded.
Best wishes
Michael

Hi Michael.

Yesterday, I finally found a way to move right and left the little bar of yaw damper of semi realistic form.

First of all, I tried the offset you told me 0808 and nothing happened, the value always was 0.

Reading the FSUIPC manual I found another value that reffers to turn coordination.
0x0380 - 32 bits - Floating point turn coordination ball position. I try all the combiations possible in mobiflight to read values but the only valid was INTEGER 8 bytes.

With this config I obtained positive values and negative to right and left. Perfect! That´s is all that we need.
In order to limit the servo movement, because we only need a little movement of the bar, I configured my servo output with the next values. servo min 15 , servo max 45, rotation 80%. The servo position center will be value 30.

To move a little the bar without matter the ofsset output values that comes from a long posive and long negative -1223232839 to + 1212129022 aprox, I have configured a Interpolation with the next values.
-1002 value 28
-1 value 28
1 value 32
1002 value 32

With this simple interpolation all the negative values will move the needle to 28 fixed value and all positive values to 32 fixed servo value. A little movement for our yaw damper gauge.

This sollution works OK for me by the moment.

Mobiflight is an excellent software, nothing is impossible if you can read the offset value!

PS: Michael, if you are from Hamburg, I have to say, that you live in a wonderfull city. I travelled last year to visit miniatur wunderland and hope come back soon!

Regards

Dear Francis,

I did it with your offset too. It is working fine. However it is not exactly the yaw damper offset but it is
showing the bar movement more or less like displayed on the monitor gauge.
I made some changes to avoid that the servo is going to its mechanical limits and to achieve a little more
amplitude around the mid position.
These are my parameters:
Servo:
Min: 1
Max: 140
100%

Interpolation:
-3000000000 value 131
-1500000000 value 110
-1000000000 value 90
0 value 72 (to set zero value exactly)
1000000000 value 60
1500000000 value 40
3000000000 value 29

Great you found that one!

Best regards Michael

p.s. Yes the Miniaturwunderland is amazing. I have been there several times and they did a great job.
I am absolutely faszinated by the perfection they did it.
If you like, you can contact me via email (please ask Sebastian for may email address)
next time you are in Hamburg, and I will be your tourguide.

Dear Michael

I will try with your parameters to improve the movement of the servo.

Thanks for all!

I will contact with Sebastian about your email to keep in touch.

Best regards and happy landings.

First of all, I tried the offset you told me 0808 and nothing happened, the value always was 0.

Reading the FSUIPC manual I found another value that reffers to turn coordination.
0x0380 - 32 bits - Floating point turn coordination ball position. I try all the combiations possible in mobiflight to read values but the only valid was INTEGER 8 bytes.

32 Bits Floating Point is NOT a 8 byte integer 32 BIt = 4 Byte.... And a Floating Point is not a integer its a FLOAT .
Use this setting and the value of offset is from -1 to +1 with a decimal value.

It´s ok if it work for you with this confusing technic..... but why do you not work with the real values from FSUIPC ?


By the Way to entry Question....
A Integer Offset with maby 1 Byte can be read SIGNED and UNSIGNED.....
Signed means the value goes from -128 to +127 Unsigned means its from 0-255
You have to think about this sometimes with special offsets !

Hi every body

To use the yaw damper with a 28BYJ-48 Stepper, this is the correct way :
Offset 0x036E Int 1
Compass mode,
255 Steps / 2040,
Transform: $*(-1),

It works for me.

Good luck

Kamal