Send EEG triggers from OpenSesame via parallel port

For my all EEG paradigms I need to send marks (triggers) via parallel port to EEG to make a stamp when stimuli occurred and which one was that.

In my lab we use Biosemi ActiveTwo 64 active electrode system which can work only with 0-255 range of values. It means you can tag only 255 event types in your recording.

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Start and stop Biosemi recording by EEG trigger

It comes pretty handy to have start and stop of EEG recording by stimulation software. I happened to me and my colleagues pretty often to run ActiveView software for acquisition of EEG signal, then prepare participant and run experiment. Then (in better case) we noticed that recording was not un-paused after a couple of minutes or (the worse scenario) after experimented ends.
At that time, I learned about EGI E-prime package for initialize recording and stop recording. After couple of tries it came to my mind that this is killer feature 🙂

Edit config file

After some research at Biosemi forum I found that is possible to edit a configuring file Default.cfg which stores many useful things.
First of all you need to locate this config file which is stored at your Biosemi software installation (where you have simply ActiveView programm). It is called Default.cfg and you need to open as text file (I really do recommend you Atom or Notepad++).
Then you need to find two entries:


And change it to your desired value:


So from now on if you send EEG trigger with value 254 Biosemi starts to record a session (you have to first click start button which initialize recording but still it is paused). Then when you want to stop recording you just send EEG trigger with value of 255.
Of course you can set those values as you want to for example 1 and 2 but it usually doesn’t make so much sense.