> For the complete documentation index, see [llms.txt](https://docs.lightact.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.lightact.com/dmx/dmx-in/control-by-dmx.md).
# Master DMX Control
To control software-level properties with DMX, you can use **Control by DMX** window.
To do this, open the **Control by DMX** window which you can find under *Tools* in the *Top Bar,* and enable it. Here you can trigger or control:
* **Master control**: Master Fade and Master Volume
* **Output fades**: Fades of Virtual outputs.
* **Global variables**.
With the **Universe** property, you can assign a Universe within which DMX values will control the above-mentioned properties.
In the *Start channels* section, the difference between two consecutive Start channels determines which Channels are reserved for each property.
By selecting the same **Universe** in the *DMX In* window, you should be able to see all the Channels that you have chosen, appear as green. If you **hover** over these Channels, you will see a tooltip with the property that is being controlled on that Universe and Channel.
## Controlling Global Variables with DMX
To control global variables with DMX you have to set them up the same way as Layer variables. More information how to do that is available in [Controlling Layers with DMX](/dmx/dmx-in/adjust-layer-variables-with-dmx.md).
