A few weeks ago a client of ours asked if there was a way to get a Remote Desktop session to go full screen across the two monitors that they had connected to their computer.  There didn’t seem to be an obvious method to do this.  Upon some further research we discovered that there was a command line option for the Remote Desktop application called /span which allows a single session to span multiple monitors.

If you have two (or more) monitors that are the same height, you could issue the following command:

mstsc /span

When the Remote Desktop application starts up it will ask you what Computer you want to connect to.  Just enter the name or IP address of the computer and you will be connected in full screen mode across your two (or more) monitors.

Some notes from the Microsoft Help about what the /span option does and its limitations:

Matches the remote desktop width and height with the local virtual desktop, spanning across multiple monitors if necessary. To span across monitors, the monitors must all have the same height and be aligned side by side.

In order to save the /span option into the .rdp file you will need to manually edit it:

• Open Windows Explorer, and browse to the folder containing the .rdp file you want to edit.
• Right-click the file > Open With > Choose Program > Notepad (or any other text editing program you have installed on your computer)
• Once the file is open in Notepad go to the bottom of the file and add the following command: span monitors:i:1
• Save the file.

Now your rdp file will automatically span monitors when executed.