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Posts: 18
I have almost finished my panel, but I have a question about ALT Hold mode. I will try to explain it with Cessna 172 G1000 (MSFS 2020).
There is a button in the G1000 panel (by now, I will talk about the plane only) with ALT name in this. It is supposed that if you have AP engaged, and press that button, the plane will mantain the current altitude. So if for example you have selected a target altitude of 10000 feet, and you are climbing in VS mode at 800 fpm, if you press ALT when at 4500, the plane will stop climbing and will keep 4500. If I am wrong, please tell me.

The question is that I try to do that, and it doesn't work. The plane don't hold that altitude. In the MFD appears label ALT 4500 in green, but the plane continues climbing. I presume that I am doing something wrong or ALT mode doesn't work as I supposed.

Lets go to Mobiflight and FSUIPC. In FSUIPC, there are two offsets: 0x07D8, which description is AUTOPILOT ATTITUDE HOLD and 0x07D0 which description is AUTOPILOT ALTITUDE LOCK.

In mobiflight I only see the first. I have a button and a led. If I make an input with any of those offsets, and press the button, the ALT mode doesn't activate in plane. I have to use an event for this. I have got the event id with FSUIPC console help, I don't remember the number, but it is not neccesary. I just asociate the button press to the event, and if i press, the plane change to ALT mode, if I press again the plane leaves the ALT mode.

For the led, I have tried with offset 0x07D8, but it doesn't change when activate or deactivate the ALT mode. The offstet 0x07D0 goes to 0 when ALT is activated, and goes to 1 when is deactivated. So I have make a formula so that the led is 1 when 0x07D0 is 0, and 0 when 0x07D0 is 1. Either way, the plane don't behaves as I supposed to do.

And more than that: if with ALT activated I press VS, ALT is not deactivated, the plane activates VS (green label on MFD), and begins to climb or descend, but when I deactivate VS, ALT is still active. It is like if it continues active in background. This doesn't happens with FLC/VS. If you press FLC when VS is active, and then you deactivate FLC, VS is still unactive, if you need, you have to press the button again to activate.

Anyone can clarify this?

Thanks in advance.
2021-01-09 22:39
From: ETSI, Germany
Posts: 5571

In case i still not use FS2020 a other user with expereience there must help you.

I just can give you 3 Basic informations.

NOTE: I not directly understand by your description if the issue is a basic problem ( Also in the Virtual Cockpit) or only a issue when you make a Input/Output in Mobiflight.

1. Mobiflight can not change the Sim Logics !
So if ALT Button for example not do what you expect... And i mean it not do also in the virtual Cockpit ( when you click the virtual button with the mouse) then simply FS2020 handle this system in it´s own way. Maybe a Bug. Maybe a feature you missunderstand.
At first you must check how the system work in the VIRTUAL Cockpit. And finaly accept... Mobiflight can never do anything else like the sim allow it to do.
So if the ALT and VS LED´s also in the virtual cockpit are working "wrong" then you can not change this.... then logical also the information you read out is wrong.
Same with the Button.... If a Press on that "ALT Button" occure in wrong action in the sim ( when you press the virtual one) then sure.... You can not solve this cause the Mobiflight input just press "internal" that virtual button.... same way you like do it with the mouse.

So final Question: Are the 2 Problems also in the Virtual situation?

2. You say a Input is Missing in MF.

Lets go to Mobiflight and FSUIPC. In FSUIPC, there are two offsets: 0x07D8, which description is AUTOPILOT ATTITUDE HOLD and 0x07D0 which description is AUTOPILOT ALTITUDE LOCK.
In mobiflight I only see the first

You pretty sure mean "Presets" . These are just a couple of elements Sebastian create as Premade stuff for a better handling. BUT You can create every Config you like. All you need to do is enter the Data yourself.
So instead of choose a Preset from the list simply insert OffsetAdress, Typ, Size and the settings by hand!


3. FS2020 and FSUIPC are BETA
As i said 1000 times the last weeks. We must accept that FS2020 got a lot of bugs till now and also that FSUIPC7 is a BETA Version that is not realy working 100%.
So it´s hard for us to say if you make a misstake OR if the feature is simply bugged by FSUIPC already.

Summary: Please Confirm the Virtual System work as it should.... If Yes confirm the Offsets work as it should .... If also Yes then we must check your config for a issue.
If the problem is confirmed in the Sim ..... Wait for a Update of Fs2020 and/or FSUIPC
Good Luck !
2021-01-10 17:19
Posts: 18
Thanks for your detailed answer. It was mainly misunderstanding by my side.

ALT HOLD mode works in a kind of confusing way. That is a mode you can select, and if you do so, the plane will hold the current altitude, regarding you have previously selected in altitude panel. As soon as you press the ALT button, the altitude at which the airctaft is at this moment, will hold, and the ALT HOLD mode is selected and shown.

I have assigned the event ID 65726 to the button ALT Hold, and when I press it, the command is working.
Then, the led which lights when ALT HOLD mode is selected, is assigned to FSUIPC Offset 0x07D0.

But there is also a situation in which ALT HOLD is selected automatically: when the aircraft reaches the programmed ALTITUDE in a FLC or VS mode. When the plane reaches the target altitude, ALT HOLD mode is automatically engaged. So the 0x07D0 offset sets to 1, and the led lights.
2021-01-24 20:25