Overhead functions - offsets and controls working with which plane?

Controls on overhead, specially for big airliners, are the most complicated part to activate on home cockpits with the default FS2020 planes.
My experience up to now with Arduino and Fsuipc / Mobiflight or even direct to simconnect, is that only 30-40% of the functions are working, and even less with default parameters or event-ids.
Very basic and simple commands like “nav lights” or “taxi lights”, or “hyd pumps”, “apu start”, etc, are not working or require a lot of trial and errors before even become partly usable.
No documentation is given for custom vars (on XPlane you find a complete list of datarefs for the Laminar B737 and you can use them easily), there is nothing like “dataref tool” to view the undocumented vars…
Even so, I managed to get working (with many “tricks”) the following controls:

  • landing lights (only one)
  • beacon lights
  • cross feed valve and annunciator
  • apu starter % (has to be set repeatedly to 100% - I use SIOC or lua for this)
  • apu stop
  • apu rpm indicator (with stepper motor controlled by MobiFlight)
  • apu bleed and annunciator
  • apu generator
  • generator 1 a/b and generator 2 a/b and gen off bus annunciators
  • generator 1 and 2 source off (when gen switch on and engine is not running)
  • fuel pumps and Low press annunciators (partly faked)
  • hyd pumps and annunciators (faked with fsuipc free offsets for the moment)
  • yaw damper (AP yaw damper and annunciator - sometimes disconnecting by itself)
  • battery switch (not always working as expected but responding)

NOT working at the moment:

  • nav lights (is only connected to other lights)
  • start knobs, gnd, cont, etc - seems not working from cold and dark situation
  • taxi lights
  • isolation valve
    all of the remainig controls
    under development:
  • pitot, wings, windows, engine anti-ice
  • windscreen wipers
  • ground power
    It would be interesting to collect informations among all home cockpit builders on this subject!

I have compiled a worksheet using the mobiflight configuration that I have tested up to now.
I can only upload images so I took 3 screenshots of the list, page 1-2-3
hope it can be useful for someone.


taxi lights work - I set the wrong bit on 0D0C offset.
It is supposed to work this way:
0 Navigation
1 Beacon
2 Landing
3 Taxi
4 Strobes
5 Instruments
6 Recognition
7 Wing
8 Logo
9 Cabin
some work pretty well, other are confusing and different from plane to plane, but can be a good starting point.


Apparently no one is interested in this subject… seems stange because, after the first phase of more urgent things (the first week even configuring decently the yoke or the throttles was not an obvious operation to accomplish) after some time and having solved the essential issues, is now time to extend the exploration to other functions.
I have big difficulties in simulating a procedure to start up engines (even Ctrl-E seems not to work on B320 and B787 from cold and dark, and the APU seems only an useless gadget).
So I hope that a future patch will fix at least the most important of the auxiliary systems…
even if we are dealing with default planes, I know that!


Nice exploring.
It looks that ‘old’ offsets working for default airplanes.

Borna :wink:

Thanks for your reply.
I greatly appreciate that MS kept most of the old variables names, and this allows to have - at least apparently - the possibility to reactivate many controls even if the specific airplanes variables are not published. Unfortunately, when you analyze the effects of many controls, you realize that they work only partially, or in a way that is not the one expected, or they respond to interrogation but even changing them you obtain no action.
Electrical systems are very roughly functional, engines start selectors are almost not working, fuel cutoff valves seems not to to work, and so on.
I found some workarounds with small SIOC code, and other functions I had to “fake” something to have annunciators working, etc.
But maybe that others have found other vars working or other event ids or commands…

I use the Citation Longitude and have the anti ice sytems working ok. I also have a
Switch working for ground power. The ground power works as a toggle at the moment
but I can probably sort that in fsuipc or change my existing latching switch for a toggle.

Here is a list of what i have working so far in the Longitude
Nav lights
Strobe Lights
Landing lights
Taxi lights
Generators 1 and 2
Batteries 1 and 2
Windscreen anti ice
Engines 1 and 2 anti ice
Wings anti ice
Pitot heat
FD,Nav,Hdg,Alt,Vs,YD, FLC,Appr
alt sel knob, hdg select knob, vs knob, speed select knob.
Com frequency knob, Nav frequency knob.
Nav source select
Nav 1/2 select
Baro sync
Parking brake
Ail trim
Rudder trim
Push to talk ( i have a number/letter pad built into my cockpit which is
actually the GCU477 of the Phenom 300 on which the cockpit is based. I
use this to choose the ATC options when speaking)

I have not been able to map as yet…
Bus tie switch
MFD map range (need to get this one sorted)

A work in progress. I am hoping to get it so that I dont have to use the mouse once
I am settled in the cockpit.

I have been using the fsuipc7 log function to trace any events that aren’t obvious
but nothing shows up for the Bus tie switch)

WOOW great!
You have really achieved a 99% success! Congratulations.
I must try my controls with the Citation; currently I am using mainly the B787 because it seemed to me the nearest to the 737, so I hoped that the overehead controls and many other things would have been similiar. Unfortunately many systems dont’ work at the moment, most of the knobs are inoperative.
With FSUIPC 7 though, either using offsets or using event ids, many functions respond, but it would be very nice from MS if they made available (and available to FSUIPC) at least the most important functions with airplane-specific variables. EFIS ND range and mode first of all.
Have you got working engine start and cutoff valves ?
And what do you use for activating LVL_change ? (on my OC mcp doesn’t work, but I have performed no code testing yet)
Thanks for your contribution.

Hi, I will get back to you with answers to your questions where possible but I am out of town at the moment so it will not be until a couple of days time.

Hi Airmax,

thank you very much for your effort.

It seem that these offsets are mainly for the 787/747, correct? Have you tested them with the A320 as well?

Thanks in advance!

Hi, some controls work also with A320, but it is a sort of random lottery… I suppose that at least the basic functions should have been made with the default variables.
Instead they used custom functions even for the most common things…
But there is something I don’t understand, in some videos I see the APU working, but if I follow exactly the same steps my APU (in 787 and in A320) starts, reaches around 5% and then stops…
I had to fake this by calling repeatedly the row “apu_starter = 100” in SIOC, and this works, but even so engines won’t start properly.
I use both FSUIPC log console for events and SIOC console to monitor the offsets and the controls, and also Mobiflight display row where you can see the current offset value.
But of course, if you don’t know which offset is used or if the variable is not yet tracked by any FSUIPC offset or event id, you have no way to understand what’s wrong and what’s going on…
Anyway I warmly suggest to install and use SIOC console to monitor offsets, even if you don’t use Opencockpits modules or boards. The console gives you a real-time vision of the offsets current values simply assigning them to a SIOC variable, you can do this with as many offset as you like, and you can see all of them changing and so you can try to find out what you need to assign to your controls and what value you have to assign.
IF that plane uses some of the variables that are tracked by fsuipc, and this is the big limitation.

Hi, I did many tests with the Citation Longitude and it seems to be a more “tameable” beast…
I was able to activate all the control needed for a full engine startup procedure, that - exactly with the same offsets and controls - doesn’t work with B787 and A320.
Here are my results:

  1. Battery seems not to work properly, there are 2 batteries switch, but even switching both off (not with default battery offsets but even in VC) I don’t see the normal range of effects on systems, as if there was external power supplied - with engines off…
  2. I can start the APU with event id 66704 and stop it with 66705 (DON’T work on 787 and A320 for me!)
  3. I can set APU bleed source setting 0B50 to 3 or to 2 to open / close
  4. I set the start knob to assign to 0892 to 1 (start) or 2 (normal position) - this causes the bleed air from APU to flow through the engine reaching 25% rpm
  5. I set the eng1mixture from lean (0) or to rich (16383) with offset 0890 and open the engine1 fuel valve setting 3590 to 1 (0 to close) - this make the engine speed up and stabilize around 60% then I can switch the starter back to 2.
    Same for Engine 2 with the appropriate offsets.
    Stepper APU gauge, generators annunciators, fuel pumps and Low press annunciators etc work.
    BUT sometimes the same sequence fails, and only toggling the VC swithces I can make the engines working, otherwise they stay at 25%, so there is some other offset to set…
1 Like

I think the batteries are using the TOGGLE MASTER BATTERY event and inputting a value of 1 or 2 into the same event for each battery, although I need to write a lua script to confirm this.

I am also seeing the engines get to 25 per cent then stop, and thisnis just using a switch tonautostart the engines, so this may be a bug… Not always though which is weird. This needs investigating too.

Good work though :+1:

Sorry, j have mislead you on the FLC. I am using my FLC button to arm the autothrottles and the knob underneath it to choose the speed setting. I am using VS to change levels.

Engines stop at 25% until you toggle the fuel valve, (you should be using the apu bleed air to reach 25%); after you toggle the fuel valve - and I also see that the simulator sets mixture to rich - the engines start to burn fuel and accelerate (or should do so…) to a stable rpm.
But I am facing a lot of oddities with every offset and event id I tested up to now, so I’m getting a bit tired of this level of precision of the simulator, I think that I’ll wait for further updates or mods before losing other hours and hours of frustrating trials and tests…

Yes , i agree. I have already lost too much flying time. The Longitude was a stop gap for me anyway because my cockpit is based upon the Phenom 300 which I am hoping Carenado or somebody else will release for msfs.

Happy flying.

Hi again,

Did you ever manage to get the bus tie switch mapped for the Longitude or perhaps the G1000 map range knob?

These are the two that I most need.

Happy new year

Hey guys, I am sorry if this is the wrong feed for it, but is there a guide how to use Offset?
I am really new to the whole programming and offsets, so where do I start?
Where do I have to program the offset into? (which file) etc.
Help is a lot appreciatedl

Hi Millsen92, offsets are a table of addresses where a program called FSUIPC (that is essential for me for home cockpit builders) continuously writes (and reads if they can be modified by the user) the variables of flight simulator. A complete list of the variables is included in the documentation of FSUIPC, for MSFS2020 you need the version 7.
I don’t know if a free version of FSUIPC is still available, but essentially the program is payware.
You can configure keys, buttons and devices to write directly some values in the appropriate offsets using only fsuipc, but many other programs can use the offsets once fsuipc is running.
EG I use SIOC (the program for the OpenCockpits devices) or MobiFlight (both are available for free).
The subject is pretty wide and complicate, but you could have a look on FSUIPC site and watch some tutorials on the net.
The (only?) alternative is to write code to read and write variables directly on the simulator via SimConnect, that is possible using only the FS2020 SDK, but requires a good level of programming skills.
IMHO Fsuipc is a base program for building a home cockpit, so after a good search and after having studied many tutorials, it’s up to you to decide if purchasing a license and do some testing, or trying other ways.

Further to my earlier posts I now have the MFD map zoom worked out and have it working in my cockpit.

For this I used FSUIPC7 and a module from Mobiflight which opens up a lot of the missing control events for the G1000, G3000 and GNS430.

I still have not worked out the Bus Tie switch for the Longitude though. Mobiflight will be adding further control events so I am hoping that this switch will be added soon.