Changing Trigger Values

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Changing Trigger Values

Post by mnaylor3 » Wed Apr 20, 2011 8:47 pm

Hi Guys,

We've been recording ERPs using Presentation. New trigger codes show up ever so often. It's puzzling.

Here is one coding system we have:


Sometimes, these codes show up:


Our programmer says that, for some reason, codes are being added together or subtracted.


Does this have something to do with ActiView?

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Post by Coen » Thu Apr 21, 2011 4:14 pm

In general, use the following guidelines to solve trigger problems:

- Use the "analog" trigger display to display the trigger lines bit by bit, colored dots and bars indicate High trigger lines
- Ensure that positive logic is used (Low = no-trigger, High = trigger)
- Return all trigger lines to Low after each trigger
- Inspect the trigger lines for increasing codes. For example: 1 = only trig line one shows dot, 5 = trigger lines 1 and 3 shows dots, etc
- Ensure that for a given trigger code, all relevant bits go High and Low simultaneously (within one sample period). If not, a trigger code will be displayed as several (other) successive codes.

Best regards, Coen (BioSemi)

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Location: Boston

Post by Aliez » Sat Jun 18, 2011 5:02 pm

Hi Coen,

I found this post related to my problem that I posted yesterday.
In addition to my previous questions, can you please explain your reply to this post a little bit more?

What does positive logic mean? & what do you mean by returning trigger lines to low after each trigger? how should we do it? (can you please provide examples)

how could we ensure that for a given trigger code, all relevant bits go High and Low simultaneously?

Thank you.

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