IMPORTANT - THIS GUIDE IS SPLIT OVER TWO POSTS, YOU MUST APPLY STEP 4 IN THE SECOND POST.

Here is my attempt at explaining how to get DCS running with a main view, and MFCDs exported to a second or third display.

I also believe following this guide in the same order as the steps provided will reduce frustration and problems. 

Step 1. - Configure your monitors correctly in Windows

You must first make sure that your monitors are correctly configured in Windows Display Settings, right click anywhere on your desktop and select display settings

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You may setup your monitors in the display settings to be side by side or stacked one above the other. 

MAKING YOUR  LEFT MONITOR THE MAIN MONITOR WILL ELIMINATE MANY POTENTIAL PROBLEMS without some special coding, DCS will count your main monitor as the starting point for all the code.

Note: You do not have to set up your displays in windows the same as you physically have your monitors setup on your desk.  All this does is change how your mouse pointer moves from one screen to the next. For example, my monitor (2) below, is physically under my monitor (1). To get my mouse pointer onto monitor (2), I have to move it off the right edge of (1), then off the right edge of (3), instead of off the bottom of (1)

Some issues with exporting the FA-18 MFCDs are reported to be because the vertical resolution exceeds 1440 pixels.

I have also found that having a display in the bottom right is better due to the placement of some DCS "screens", the HUEY crew display and NS430 GPS pop out window for example. This issue mainly arises if your monitors have different resolutions, or are stacked in Display Settings.

 This is my setup, I have a 27inch 1440p as my main monitor (1), a 24inch 1080p monitor (3) and a 11inch 1080p monitor (2)

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Make sure your main monitor has the Make this my main monitor check box ticked, and

all of your displays have Extend desktop to this display selected in the drop down box

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The display edges must be perfectly aligned to aid with exported display positioning, drag both your main monitor and other monitors around until the edges are perfectly aligned.

They don't have to be perfectly aligned, but it certainly helps when trying to position your exported displays later on, and figuring out your total resolution.

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Step 2. - Calculate your in game resolution

Your in game resolution is calculated by adding up all of your screen resolutions. edit, or at least the screens you want DCS to use as gaming space

For me, my in-game resolution is 6400x1440

2560+1920+1920=6400

1440 is my tallest monitor in pixels

Some other examples

A 1440p panel and a 1080p panel 3640x1440

 Two 1080p panels 3840x1080

A 1080p and one 1024x768 7" display 1920x1848

a 1080p panel and 2 lilliput displays  1920x1680

Hold onto to that number for now

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3. Configure a DCS monitor setup file

We now need to configure a monitor setup file. Notepad++ is a free editing tool and can be downloaded here  https://notepad-plus-plus.org/downloads/ Some issues have been reported while editing .lua files with Windows Notepad

The files are located in two locations.

The default monitor config files are located: eg C:/Program files/DCS World/Config/MonitorSetup note: these files may be overwritten during updates or repair

Your personal monitor config files are located: Saved Games/DCS/Config/MonitorSetup note: these are NOT overwritten during updates or repair "Windows Saved Game" folder can be found by searching for Saved Games in the start menu search function.

The default files are set to be semi-automatic. I don't find them to be much use personally.  For example, Camera+LMFCD will fill your second screen with the Left MFCD, but it probably won't have the correct proportions.

I'm going to explain the way I do it, which I think is easier to understand.

If you don't yet have the folder

Saved Games/DCS/Config/MonitorSetup/

I suggest you create it. I have included a very basic monitor config .lua file here --------------------------> My testing config.lua It is based on a two monitor configuration, both with 2560x1440 resolution

So lets have a look at a monitor setup file:  First, I suggest you change the name inside the file to something memorable. (line 2) This is the name shown within the DCS settings menu.

DCS uses a system of "Viewports", and Viewports are basically "windows" within DCS. In the monitor setup file, we tell DCS where to put the Viewports, and what size they should be.  

When we give a Viewport a position, we are telling DCS where the top left corner of that viewport will be. The x and y coordinates. To set the size we use the width and height settings. DCS works on a left to right system for x in pixels, and it works on a top to bottom system for y in pixels.

Breaking down the above example:

The Center viewport is:

x = 0 ---- this describes where we want the left edge of the viewport to be, in this case zero, it will be all the way to the left Y = 0 ---- this describes where we want the top edge of the viewport to be, in this case zero, it will be at the top. width = 2560 ----it will be 2560 pixels wide, counting from the left height = 1440 ---- it will be 1440 tall, counting from the top viewDx and viewDy are offsets used when you want to split up the cockpit view over many monitors, not covered in this MFD guide. Aspect = 2560/1440 ---- This is simply width divided by height.

the Left MFCD is x = 2560 ---- 2560 pixels from the far left of the total resolution, this will put it on the left edge of the second monitor y = 60 ---- 60 pixels from the top, from the top of the very top left corner of the entire resolution width = 825 it will be a 825 pixels wide height =825  and 825 pixels tall, making a square.

the Right MFCD is x = 3385 ---- 3385 pixels from the far left of the total resolution, this will put it 825 pixels in from the left edge of the second monitor   2560+825=3385 which in this case will be touching the Left MFCD y = 60 ---- 60 pixels from the top, from the top of the very top left corner of the entire resolution width = 825 it will be a 825 pixels wide height =825  and 825 pixels tall, making a square.

UIMainView and GU_MAIN_VIEWPORT The UIMainView is normally equal to viewports.center. That should be fine, but, I have seen multiple people with the issue of the Comms menu not being confined to the main screen, or the controls indicators are weirdly placed, or the F10 mouse pointer has some sort of offset (made be a cubesim only issue?), or the gunsights in combined arms vehicles are split across screens. By manually setting the parameters of the UIMainView and adding the GU_MAIN_VIEWPORT, and setting them both to the same as your main view, at least some of the issues are fixed. This diagram shows how that works out

Although monitors have bezels, there is no pixel gap, the next screen is the next pixel.

The GREEN shows the total resolution, the numbers we use for DCS The DARK GREY box is the center view. 2560x1440 The BLUE is the MFCDs The RED is the individual screen resolutions

Lets have a look at another example when using monitors with different resolutions. This is my setup.

so for me, above, my center viewport is:

x = 0 ---- this describes where we want the left edge of the viewport to be, in this case zero, I want it to be all the way to the left Y = 0 ---- this describes where we want the top edge of the viewport to be , in this case zero, I want it to be at the top. width = 2560 ---- I want it to cover my whole main monitor screen, left to right height = 1440 ---- I want it to cover my whole main monitor screen, top to bottom viewDx and viewDy are offsets used when you want to split up the cockpit view over many monitors, not covered in this MFD guide. Aspect = 6400/1440

my Left MFCD is x = 4490 ---- 4490 pixels from the far left, this is because my main screen is 2560, the next screen is 1920, and I want it to be on my third screen, but 10 pixels in from the edge, 2560+1920+10 = 4490 y = 360 ---- 360 pixels from the top, this is because my main screen is 1440 pixels tall, but my third screen is only 1080, and the top of third screen is 360 pixels below the top of my main screen. 1440-1080=360 width = 825 how wide I want my MFD to be in pixels from left to right height = 825 how tall I want my MFD to be in pixels from top to bottom

my Right MFCD is x =5570 ---- 5570 pixels from the far left, this is because my main screen is 2560, the next screen is 1920, and I want it to be on my third screen, but 1090 pixels in from the edge, 2560+1920+1090 = 5570 y = 360 ---- 360 pixels from the top, this is because my main screen is 1440 pixels tall, but my third screen is only 1080, and the top of third screen is 360 pixels below the top of my main screen. 1440-1080=360 width = 825 how wide I want my MFD to be in pixels from left to right height = 825 how tall I want my MFD to be in pixels from top to bottom

Alternatively you can specify x and y like this

take my Right MFCD for example

x = 2560+1920+1090 ---- 5570 pixels from the far left, this is because my main screen is 2560, the next screen is 1920, and I want it to be on my third screen, but 1090 pixels in from the edge, 5570=2560+1920+1090 y = 360 ---- 360 pixels from the top, this is because my main screen is 1440 pixels tall, but my third screen is only 1080, and the top of third screen is 360 pixels below the top of my main screen. 1440-1080=360 width = 825 how wide I want my MFD to be in pixels from left to right height = 825 how tall I want my MFD to be in pixels from top to bottom

This small program can help with finding coordinates, thanks @Pipe You can drag the window around and resize it, and it will report the position and size of the window, very handy.

http://breakthrusoftware.com/html/onlinedocs/kb/installkb/ScreenCoordTool.html