Using Multiple Monitors in Remote Desktop Session

Using Multiple Monitors in Remote Desktop Session

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Introduction:

Multiple monitor support for Remote Desktop Services allows users to open a Remote Desktop connection expanded across all the monitors on the client computer regardless of the client monitor configuration. With this feature, the user can fully utilize all the monitors connected to the client computer for the Remote Desktop connection thereby providing extra desktop space and an almost seamless experience with the client desktop that is much improved over “Span mode”.

This feature will be part of Windows 7/Windows Server 2008 R2 release and works for connections to another client machine (physical or VM), or a Remote Desktop Session Host.

How to use Remote Desktop Multimon feature:

To use this feature, you must:

  1. Connect using the Remote Desktop Client 7.0 (mstsc.exe) available initially on Windows 7/Windows Server 2008 R2.
  2. Enable Multimon using one of the three methods described below:
    a. Click “Use all monitors for the remote session” in the client (mstsc.exe) window.
    b. Use the “/multimon” switch on the mstsc.exe command line.
    c. Add “Use Multimon:i:1” to the RDP file.
    image 
  3. Connect to a computer running Windows 7 or Windows Server 2008 R2.

How does it look?

Currently this feature displays the remote desktop on all the monitors available on the client computer. It can handle any client monitor configuration supported by Windows.

The following images show the Remote Desktop Multimon feature in various configurations:

image

Display Settings UI inside a Remote Desktop session showing multiple monitors

image

Remote Desktop Multimon Session with 5 monitors

image

PowerPoint inside Remote Desktop session showing multiple monitors

How is this different from “Span” mode?

Span mode, introduced in Vista, allows the remote desktop to span across all monitors on the client as long as the monitors are arranged to form a rectangle. The remote session created when using span mode is still a single-monitor session. With multimon support, each monitor on the client machine is viewed as a distinct monitor in the remote session. Due to this fundamental difference, span mode has some restrictions that true multimon does not:

1. The primary monitor must be leftmost.

2. The set of monitors must form a rectangle (i.e. identical vertical resolution, and lined up in exact straight line).

3. The total of the resolutions must be below 4096x2048 (ex. 1600x1200+1600x1200 = 3200x1200).

For these reasons, all monitor configurations shown below are valid for Remote Desktop multimon, whereas most of them are not valid for span mode:

SpanConfigs

With true multimon support, the client-side monitors can be arranged in any order and can be of any resolution.

Since a span mode remote session is essentially a single-monitor session, if a window in the remote desktop is maximized, it spans across all the monitors. With true multimon support, a window will only maximize to the extent of the containing monitor.

If an application queries for the number of monitors inside a span-mode session, it will find only one monitor, whereas it will find as many monitors as are actually present on the client system when using true multimon RDP. This difference can change the behavior of applications such as PowerPoint.

Remote Desktop Multimon configuration properties:

There are a few settings associated with the Remote Desktop Multimon feature that can be used to restrict the number of monitors and resolution that clients use to connect.

Restricting the maximum number of monitors:

The Remote Desktop Multimon feature provides an option to restrict the number of monitors a user can use to connect. By default, RDP protocol supports a maximum of 16 monitors. This number can be restricted to any value between 1 and 16 using one of the following three approaches:

  1. Using the “Limit maximum number of monitors per session” setting in the Remote Desktop Configuration Tool (tsconfig.msc) as shown below:
    image
  2. Setting the “Limit maximum number of monitors” machine group policy as shown below:
    image 
  3. By setting the MaxMonitors property in the Win32_TSClientSetting WMI class (http://msdn.microsoft.com/en-us/library/aa383778(VS.85).aspx).

Restricting the maximum resolution of each monitor:

By default, RDP restricts the maximum resolution to 4096 X 2048 per monitor. Additionally with multimon, the width and height of each remote monitor can also be restricted in one of two ways:

  1. Setting the “Limit maximum display resolution” machine group policy as shown below:
    image 
  2. By setting the MaxXResolution and MaxYResolution properties in the Win32_TSClientSetting WMI class (http://msdn.microsoft.com/en-us/library/aa383778(VS.85).aspx).

Please note that the policies and WMI settings described above apply only to connections with multiple monitors and not when connecting with a single monitor.

Leave a Comment
  • Please add 5 and 4 and type the answer here:
  • Post
  • Does multimonitor support available through RDP activeX? What properties/function call can provide multimonitor support? Is different API there for Span support through ActiveX?

  • the /multimon support in mstsc is wonderful, but here's something we're struggling with: we want to be able to limit the number of monitors to 2 per session, but are not able to do so for a client connecting with 3 monitors.

    In other words, the restriction seems to be all or nothing: when we limit to 2 monitors, any client attempting to connect with more than 2 monitors gets only one display. We want them to end up with a session that uses 2 / 3 displays.

    Is this possible?

  • Seems that this is broken if the admin attempting Remote Control of TS session is utilizing more than the number of monitors that are available in the administrator's session.

    Or maybe remote control is simply broken whenever for multiple monitors? This will be a pretty serious limitation for us, given how much run our helpdesk.

  • Hi Andrew,

    Unfortunately today it is not possible for a user to connect with more than one, but fewer than all of the monitors on their client device.  Whenever the /multimon flag is used, it will attempt to use all monitors, and if that fails due to a restriction it will fall back to a single monitor.  

    We do appreciate the feedback that this scenario is something our customers are interested in, and it is something we will keep in mind in the future.

  • Does multimonitor support available through RDP activeX? What properties/function call can provide multimonitor support? Is different API there for Span support through ActiveX?

  • @ Casey: thanks for the clarification regarding all-or-none with the mstsc /multimon switch.

    Any thoughts on Remote Control / Remote Assistance compatibility as it relates to multiple monitors? It seems that when I (as the administrator) attempt to remote control a multiple-display remote destkop user session, the remote control initiation fails if I have fewer monitors than the user session. Wouldn't the desired behavior be to at least show the primary monitor in such instances?

  • I too am having the issue where when I try to remote/shadow a user connected to a 2008 R2 server with the "Use all monitors" checkbox is the RDP7 client it fails(They have 2 monitors). I have 2 monitors myself and use the Use all Monitors setting and I always will get an "Access is Denied" error. I REALLY need resolution to this as it is stopping our rollout of 2008 R2. I'm running Win7 Pro on my desktop.

  • Leaving this capability out of Windows 7 Professional is inexcusable.

    Initially advertising it as available on Windows 7 Professional and that not being true is inexcusable.

    I hope someone releases a third party hack or patch to enabled this.

    A "Professional" grade operating system should be professional.

  • I second that Andy.  This misrepresentation has caused me to spec and purchase incompatible software for my client.  Not to mention the lost time.

  • 30" monitor rotated to Portrait mode = 1600x2560 resolution.  Windows RDP limits the session to 2048 vertical and centers the image.  Windows 7 Ultimate on both systems.  

  • I can't believe I have to re-type this (stupid sign-in).  I'm having the same issue as Kamil.  My first posts in July of 2009 were answered quickly, so I hope I can still get a good response on this old blog post.

    I seem to be pushing the envelope again with 4 x 30" montiors rotated (using nVidia control panel) to Portrait and Inverted Portrait orientations.  That means each monitor's resolution reads 1600 x 2560 for a total desktop size of 6400x2560.  When we try to run a Remote App in this configuration it is limited to the top 3/4 of the primary monitor only, or a desktop area of 1600x2048.  We have verified that the Remote App works flawlessly across all monitors when the rotation is set to Landscape (the default, wide screen) mode.  Basically we are asking if the multi-monitor capability is limited (like Andrew's post from 4/11/10) by using a display with vertical resolution greater than the max allowed, even though the display *area* is still less than the max supported?

    Also, is there anything we can do to address this on our end?  We've already discovered that the group policy editor will not allow a horizontal resolution greater than 2048.  We have experience with registry settings and hotfixes to get greater resolution under Server 2003 TS, but want to do our homework before attempting that with 2008 R2.

    Thank you,

    -John B

    P.S.  Bonus round: to what degree does using a Windows Areo theme effect the multi-monitor capability?

  • I purchased Windows 7 Professional because the feature list included Remote Desktop support with True multi-monitor support.  Then Microsoft changed their websites to say that only Windows 7 Ultimate & Enterprise supports it.  I feel entitled to a free upgrade to Ultimate or Enterprise if Microsoft does not address this problem via a Windows Update for Windows 7 Professional.

  • I really liked your blog quite informative and interesting

    facts and figures you have discussed on your blog even the

    comments are very fruitful and helpful in enhancing the

    knowledge regarding the topic.

  • I'm still unclear: Does the Windows 7 computer you are remoting INTO have to be the Ultimate or Enterprise versions of Windows 7? I have some users who swear they are getting multimon to work remoting into a Windows 7 Pro machine, but I can't recreate that experience.

  • I'm going to pile on here regarding true multimonitor support for Windows 7 Professional on the remote end.  A lot of us have control over our home setup but no control over the work system.  In my case, my IT department provided me with a Win7 Pro system.  Getting them to upgrade this to Ultimate or Enterprise is not a possibility for me.  I have a triple head setup at home running Win7 Ultimate and it really stinks that I am limited to a single display when connecting to the work system.

    Also, the FAQ located here: windows.microsoft.com/.../Remote-Desktop-Connection-frequently-asked-questions is STILL not clear.  It doesn't state which system (local or remote) requires Win7 Ultimate/Enterprise... so someone with my situation might be misled to believe it should work.

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