Triggers show in ActiView but are missing in saved recording.

[LMarreel]

Hi Anyone who can help,

We are experiencing a weird event where ALL our triggers are showing up perfectly fine on the ActiView interface. However, when then loading the saved bdf file in any way we can think of, several triggers are missing. There are generally between 100 and 400ms between these triggers. I wondered if sending from nested functions could be the issue, but this seems to only hinder a few. While others come through just fine.

If it is helpful we are sending triggers from MATLAB to Biosemi via parallel port. Specifically we use InpOut32Drv Driver Interface DLL Modified for x64 compatibility and built by Phillip Gibbons (Phil@highrez.co.uk). http://www.highrez.co.uk/Downloads/InpOut32. v1.5.0.1.

%define port
port = 'DEFC'

%check driver status
driver = io64
status = io64(driver)

if(status ~= 0)
error('InpOutx64 installation failed!')
else
disp('InpOutx64 (re)installation successful.')
end

%send message
binMsg = 3;
io64(driver,hex2dec(port),binMsg);

I don't know where to start trouble shoot as the triggers are clearly being sent. They show up with decent time intervals between them. Yet they do not show up in the saved recording.
Any advice would be much appreciated.

Best wishes
Lena

[Coen]

ActiView displays the actual data that is streamed to BDF file, there cannot be a discrepancy between display and file. Check the triggers in ActiRead for confirmation ( https://www.biosemi.com/download/ToolsF ... 02-Win.zip ). Consequently, there must be an error in your file reader.

Best regards, Coen (BioSemi)

[LMarreel]

Hi Coen,

Thank you for your reply. I am aware how odd this is, it is unfortunately what I have been observing. We tried several ways to read the files, different software and it is the same for all of them.

Regarding ActiRead, is there a way to see the decimal values of the triggers? I see colored lines but don't really know what they mean or how to use them to differentiate between my triggers. I am including some snap shots of the reader in a follow up comment, could you please tell me if this looks all normal?

A pattern I noticed and wonder if it is at all meaningful. When sending triggers and having them displayed as decimals during recording, some appear in the upper line (e.g., 13) and some the lower line (e.g., 5 ). Those in the upper line I find back in the recording, but the lower line do not?

triggershighandlow.PNG (42.02 KiB) Viewed 11915 times

Many thanks for helping me understand and troubleshoot.

Best wishes

[LMarreel]

The triggers in ActiRead look as follows (note difference in display length)

[Coen]

The colored lines show the trigger lines 1-16 (colored when High). Use ActiTools to convert to decimal values. The errors in other file readers are because you do not pull all trigger lines Low after each trigger. In ActiRead, you should see colored dots, not lines. Use the "analog" display mode in ActiView for a similar display, see https://www.youtube.com/watch?v=0BPwcciq8u8 .

Best regards, Coen (BioSemi)

[LMarreel]

Could I ask you what you mean with '' puling trigger lines Low''? Is this like '' clearing the trigger channel'' and can this be done by sending a zero value after every trigger I sent?

[Coen]

Yes, send a zero (lines 1-8 Low) after each trigger. The trigger length should remain longer than the sample period (otherwise triggers can be missed), best regards, Coen