Trigger Codes Missing Sporadically

Post Reply
isaacsda
Posts: 4
Joined: Tue Jul 30, 2019 5:35 pm

Trigger Codes Missing Sporadically

Post by isaacsda »

I am running an auditory ERP task with e-Prime 2 Professional (version 2.0.10.356) on a Windows 10 OS (version 1709). In e-Prime, I have configured a task event to send a trigger label via the serial USB-Trigger Interface cable to a laptop with ActiView. The auditory stimulus occurs in a train of 4, followed by a longer inter-train interval. The train of 4 should consistently appear as follows in the ActiView trigger bar:
ActiViewScreenshot1.jpg
ActiViewScreenshot1.jpg (4.52 KiB) Viewed 9828 times
However, randomly, one of the trigger labels often fails to appear:
ActiViewScreenshot2.jpg
ActiViewScreenshot2.jpg (4.71 KiB) Viewed 9828 times
It is not always the same trigger label, and at other times, all of the labels appear without issue. With the USB-Trigger Interface cable, I was under the impression I did not need to reset the trigger label to 0 after each task event, but, just to troubleshoot, I tried this, but the issue has persisted. If anyone has any guidance / recommendations to resolve this problem, I would be very grateful. Thank you for your consideration.

Coen
Site Admin
Posts: 1124
Joined: Fri Mar 26, 2004 7:00 pm
Location: Amsterdam, Netherlands
Contact:

Re: Trigger Codes Missing Sporadically

Post by Coen »

1) Set the trigger format (lower left corner) to "analog" to troubleshoot. You can then identify 16 separate lines (bits). Colored dots/bars indicate a that a line is HIGH. grey background indicate that a line is LOW.

2) Use positive logic: HIGH is trigger. LOW is idle (with negative logic, triggers may be missed when down-sampling/decimation in ActView is applied)

2) Pull all the (used) lines LOW between the triggers (often, only the lines 1-8 are used for triggers 0-255)

3) The trigger length must be longer than the hardware sample period (> 0.5 millisecond on 2 kHz sample rate), or else triggers may be missed.

Best regards, Coen (BioSemi)

isaacsda
Posts: 4
Joined: Tue Jul 30, 2019 5:35 pm

Re: Trigger Codes Missing Sporadically

Post by isaacsda »

Coen,
Thank you for the prompt response. I followed your instructions but was still having some issues. I then tried changing the trigger signal command in ePrime 2 software, using a WriteByte command as opposed to a WriteInteger command. That seems to have solved the issue, with no further dropped trigger signals in the analog view mode. Thank you for your help!
David

Post Reply