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Triggers are not consistently sent to BioPac


I am using Opensesame in conjunction with BioPac for the recording of ECG and EDA signals. When triggers are sent by the opensesame software, they are not consistently recognised, that is at times it is recognised by the BioPac system and at other instances, it does not. (There is no logic to when a trigger is recognised)

When triggers were sent through the USB TTL , the BioPac system is able to recognise them. Additionally when trigger are sent through command line python script, the triggers are also recognised by BioPac (however it is only every second trigger that is being recognised). (Note: in opensesame, every second trigger by rule is not recognised by BioPac the order of recognition is random)

Does anyone know why this is happening, or whether it is an issue with Opensesame or with BioPac?

This i s the setup inline script

from serial import Serial
exp.trig = Serial('COM4', 115200)

And this is the inline script everytime I want to send a trigger



  • Hi,

    I don't know much about BioPac, so these are just wild guesses:

    1) Try to add some time between the two triggers

    2) Does is still skip the second one if you use another value than 0?

    Let me know how it went,


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