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Midi, Qlab & ETC Eos


Recently I have been working on a show at a theatre that is basically a game installation. There is a game that has been developed that runs in the space. The audience generate data and at the end of the game it gets displayed on the screens. This part of the show uses OSC commands to communicate between various macs dotted around.

QLab is the main controller of the show. It fires audio and midi cues, which in turn tell the lighting console (ETC EOS) and the video/game controller mac (running Isadora) what to do in the show. All of this is all programmed into QLab so the DSM controls the game progression.

Before you start

Never expect MIDI to work first time. Something will be broken somewhere. I had a vague idea of how it all worked and connected together, but I had a google before I tried to see if there were any quick and helpful guides on how to do it. But there weren’t. So here I am writing one. I’l cover how to setup a QLab cue to fire an LX cue on an ETC EOS.

Signal Path

Here is a simple diagram showing how I had this part of the system connected. You can simply swap out the USB Midi unit for any Sound Card with midi – as you are more than likely going to be using one with midi on it.

midi sig pathAs you can see, we had the ETC Net3 Show Control box for accepting the midi into the lighting desk.

EOS Midi/MSC Settings

ETC have a useful page on their website showing how the desk will receive the midi. It actually uses a special blend of midi called Midi Show Control (MSC). This is Midi messages formatted in a certain way to help keep things simple from a programming point of view. You can read more about it here, although you don’t need to understand the actual string of data being sent; as QLab does all that for you.

This image taken from the website linked to above shows where the settings are that you will need to enter on the EOS.

Device ID Settings

Find the above page at Browser > Setup > Show Settings > Show Control And here is what you need to enter:

  • MSC Receive -> Enabled
  • MSC Transmit -> Disabled
  • MSC Receive Channel -> 0
  • MSC Transmit Channel -> 0

I suggest setting the transmit to disabled, as we are simply not using it in this example. You can toggle the MSC Receive here if you are programming, and want the QLab guy to stop firing your LX cues. (I suggest making a toggle key on a Magic Sheet!)

Note: We had to reset our Net3 Show Control box to its default settings as a previous show had messed around with it. If you can’t get it working, its probably best to do the same – reset the network settings on the Show Control box and the desk.

QLab Midi Settings

As was mentioned above, the EOS uses the MSC format for receiving and transmitting midi. You can read up on it if you google it.. Here’s what to do in QLab

  1. Go into settings and select midi from the left hand side. You will need to select the midi interface you are using in the dropdown menu for patch 1. (I am using MidiMock – a virtual device – in this example)midisettings
  2. Drag in a Midi Cue to the workspace and go to the settings tab. You will need to make sure it is set as the image below shows.
  • You can see I have selected 1 -MidiMock IN as the Midi Destination (we set that up in the previous step)
  • I have changed the Message Type to Midi Show Control Message (MSC) as this is what the EOS will respond to.
  • Command Format is All Types.
  • Device ID is set to 0. (This translates to the MSC Receive Channel in the EOS settings.)
  • I have entered 44 as the Q Number. This Midi cue will now fire LX cue 44 on the EOS. You can enter point cues too (e.g. 63.2).

If you click on Send Message on the right hand side, you can send the message to the lighting console to test it without stepping through the cue list you have created. This is great for quickly testing that the Midi link is working ok.


This guide shows how the numbers relate to each other on the different devices. If you really can’t get it to work, I suggest getting a Midi sniffer programme to see if you are correctly outputting Midi.




James is a freelance Sound Engineer in the East of England. He works for a variety of companies specialising in different sectors of the industry.