HELICOPTER event trim set

[MSFS 2020] Bug Reports Aircraft
1

Hello,
I’m trying to set the ROTOR_LONGITUDINAL_TRIM_SET variable or the ROTOR_LATERAL_TRIM_SET variable.

According to the documentation, it should be between +/-16384

If I enter a positive value in my program, it returns the correct value between 0 and 1 controlled via the variable ROTOR LONGITUDINAL TRIM PCT or ROTOR LATERAL TRIM PCT, but if I enter a negative value, the variable ROTOR LONGITUDINAL TRIM PCT or ROTOR LATERAL TRIM PCT returns 1, so I can’t get a negative value.
I don’t know if I’m doing something wrong or if it’s a bug

1 Like
2

ROTOR_LATERAL_TRIM_SET and ROTOR_LATERAL_TRIM_SET are Event variables (KVars) .

If you are using SimConnect to set an Event variable with ’ SimConnect_TransmitClientEvent’, the third parameter - ie ‘dwData’ - is defined as a DWORD (which is normally a signed Integer). However, for KVars that parameter must always be set as an Unsigned Integer (no negative numbers) .

To set a negative value you will need to convert the value you want to set to the Unsigned Integer representation of the negative number.

Check out this reference: “MSFS - Managed SimConnect Library doesn't take negative values using VB .NET 2019 and TransmitClientEvent() | FSDeveloper” for an example of how to do that if you aren’t sure.

So as examples - to set ‘-1’ as a value the converted value is 4294967295
while ‘-16384’ converts to 4295950912

It’s not really a bug per se - more an unclear and incomplete description in the documentation.

3

Thank you for your answer, it could have been the right way but unfortunately it’s not.
I didn’t specify that my program was in JS.

To test, use coherent Gt debugger:
And in the console type : SimVar.SetSimVarValue('K:ROTOR_LONGITUDINAL_TRIM_SET', 'position', x );
or x = the value you wish to use.

Whatever the value, you’ll see that the helicopter tilts to the tail.

By the way, the AXIS_CYCLIC_LONGITUDINAL_SET variable in the doc uses the same parameters, and it works.

https://docs.flightsimulator.com/flighting/html/Programming_Tools/Event_IDs/Helicopter_Specific_Events.htm

4

OK. Well sorry I couldn’t help you directly but I hope what I said will help anyone using managed code (VB.NET or C#) to set a KVar value via SimConnect. It certainly works for me.

5

Hello @DeelLav

I logged a bug for these 2 key events as they do not allow negative values.
There is no workaround unfortunately.

Regards,
Sylvain

6

Dear @FlyingRaccoon,

first of all thanks for logging the bug since this is cruicial for some further development for a project we are currently working on.

Is there a possibility that such bugs are fixed for MSFS24 even before the next SU for MSFS2020 drops? Just making sure to see how long we potentially have to halt further development.

Thanks!