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Posts: 2
Dear all,

Recently I have started building my own MCP for the pmdg 747 QOTS II v3. (P3D v5) mobiflight v 8.2 Arduino mega 2560 r3

I must congratulate the mobiflight team on making such a nice piece of software for interfacing, thank you.
After going through a lot of tutorials here on the forum, I have to admit defeat, even if it has caused others the same problems, which they resolved.

I have connected 2 LCD displays on my mobiflight mega.

All the functions are working, except blanking the v/s window and spd window when other modes are active such as operating on the FMC speed or VNAV/FLCH.
switching between IAS / MACH works fine.
However I do manage to write "off" on the display next to the speed value when it is supposed to be off, this is just a silly work around though..

I want to tackle the V/S speed window not blanking first since that seems a good learning excercise, with less variables then the speed window.
I have been reading all of the topics, following them, allas to no avail, the last value before switching off remains on the display.

basic info:

pmdg uses offset 65A2 as MCP_vert speed
then offset 65A4 as MCP vert speed blank

What I have done:

I made 3 configs,

1) offset 65A2 named MCP v/s - precondition vs blank = 1
2) offset 65A4 named VS blank - precondition vs psuedo blank = 0, compare if 0 then "5 spaces"
3) offset 65A4 named VS pseudo blank precondition vs blank = 0

In the display config I programmed use config MCP v/s with sign &&&&&
use VS BLANK in same space with same sign &&&&&

I am sorry to ask about this again when others had similar problems (777), but I have tried many different configs, can not get it to work...
any help will be greatly appreciated.

Thank you all!
2021-07-23 18:47
From: EDDG, Germany
Posts: 1819
Hi hollik19,

Welcome to MobiFlight,

please look here:

This shows you an example how to solve your problem. It's for the PMDG 777. Look for the offsets to you PMDG 747 QOTK
Stephan (Time: UTC+1)
2021-07-27 19:42
From: ETSI, Germany
Posts: 5501

Here we get multiple problems...... The "Guide" is not perfect here.

1. Wrong System.
As Stephan said.... the guide was already done for the B737 ( Long years ago) and for the B777 ( later with more complex stuff)
For the B747 there is no guide yet..... Pretty sure its nearly simmular..... But may some elements are different.
I not own the B747 so i can support you but can NOT give you a final solution directly.

2. Wrong / outdated Technique.
The usage of Multiple configs and Precons was done long time ago before "Placeholder/ Config Refferences in Syntax" was possible. Today we would make those configs much more easy.

3. Wrong Hardware
The guide is based to 7Seg Displays ( Like used in the Real Aircraft and used by 99% of Boeing Cockpitbuilders)
A LCD work different..... So the "Guide" is not usable 1:1 ..... You need to think a little different if you use a LCD.


Please report if Problem is still exist..... If Yes. Try to join our Discord Server and contact me ( Sorry but for now my time is pretty limmited)
Then we can figure out this "live" with shared screen together and finaly we can offer a Gudie for the 747 with LCD to the community!
Good Luck !
2021-07-28 16:38
Posts: 2
Dear Stephan / pizman,

Thank you for your replies, unfortunately I haven't been able to be behind the computer because of work, for me the speedwindow is a visual clue of the airplanes configuration, apart from the most important, the FMA / PFD indications, especially in the scope of how we use our flightsim, we might not always have a view of the PFD, when we try to find a button on the overhead for example..

However when I have the opportunity again I will look into getting this to work again and possibly seek some additional help / share findings.

I appreciate that the 7 seg display looks more like the real aircraft, however LCD for me has some advantages. My intention in the end is to reduce the size of the mcp so it fits easily under my monitor, and a LCD can just fit more information in less space..
2021-08-17 03:15