Mssing Triggers

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ReneS
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Joined: Mon Aug 12, 2019 11:17 am

Mssing Triggers

Post by ReneS » Mon Aug 12, 2019 11:25 am

Hey,

We are currently setting up a new EEG Lab using the BIOSEMI system. For that we are using a Linux PC with MATLAB/Psychtoolbox as stimulus computer and Windows 10 as Recording computer (ActiView 806 installed).

Sending triggers from the Linux computer via the BIOSEMI USB trigger cable works fine, we tested this using a Blackbox toolkit. All the triggers send get recorded as normal. However, when we connect the USB cable to the USB receiver (and the windows 10 computer) the triggers won't show up in the ActiView software.

Any ideas why that could be?

Kind regards,

Rene

Coen
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Re: Mssing Triggers

Post by Coen » Tue Aug 13, 2019 5:28 pm

How did you establish that you are actually sending triggers when you do not see them in ActiView ?

Best regards, Coen (BioSemi)

rahulag801
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Joined: Thu Aug 08, 2019 9:32 am

Re: Mssing Triggers

Post by rahulag801 » Fri Aug 16, 2019 12:51 pm

Hi Coen,

I am working with Rene on this problem. We are using blackbox toolkit (BBTK) system which confirms that Biosemi USB trigger Interface cable send trigger signals to blackbox toolkit system. We are using matlab to send triggers (serial port) to BBTK.

When we send trigger signals to ActiView software we cannot see the trigger.Although when we manually send triggers using F1, & F2 etc. we can see it on the ActiView software.

Any idea what is happening?

I apologize for delay in response

Regards,
Rahul

Coen
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Re: Mssing Triggers

Post by Coen » Fri Aug 16, 2019 1:57 pm

The blackbox toolkit (BBTK) system has a 25-pole TTL input connector. Did you actually make a 37 to 25 parallel cable ?

Test the trigger port on the USB-receiver as described in post 4 in viewtopic.php?f=1&p=3615#p3615 (short pin 1-16 to pin 37). If the port responds OK, then you are still not actually sending triggers to the 37-pole plug on the USB trigger interface (confirm with voltmeter or oscilloscope).

Make sure your triggers are longer than the sample period (e.i. > 0.5 ms on 2 kHz)

Best regrads, Coen (BioSemi)

ReneS
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Joined: Mon Aug 12, 2019 11:17 am

Re: Mssing Triggers

Post by ReneS » Mon Aug 19, 2019 2:26 pm

To answer your question: Yes, the guys from BBTK specifically made a 37 to 25 parallel cable for us, as we asked for a way to test a setup with the Biosemi system.

To the problem at hand:
I tested USB receiver as asked today and everything seems to be in order. When the cable is disconnected all pins are high, and as soon as I short either of the 1-16 pins to pin 37 the corresponding pin goes to low.
I also checked that the RespSwitch setting in the CFG file is set to 0.

We tested sending the triggers with the I/O port function by psychtoolbox as well as the BioSemiSerialPort function made by Roee Gilron and suggested by Cortech ( https://cortechsolutions.com/ufaqs/can- ... wo-system/ )

As I said earlier, we are able to register the triggers with the BBTK (using the extra cable) without time delay.

Do you have any more ideas?

Regards
René

Coen
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Re: Mssing Triggers

Post by Coen » Mon Aug 19, 2019 3:12 pm

There might be a bad ground connection (pin 37). Check as follows:

Disconnect the USB cable from the USB-trigger interface. Plug just the USB-trigger interface (without USB-cable) into the USB-receiver and confirm that all triggers 1-16 change from HIGH to LOW.

Best regards, Coen (BioSemi)

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