[solved] Sending triggers to Nexus Trigger Interface via serial port

skinnerwinner · May 2013

Hi!

My name is Daniel and I'm currently working on an experiment with our new Nexus-32 eeg. As the title reveals, I'm having some problems with the triggers sent to the Nexus Trigger Interface (NTI) via serial port. Even your tutorial didn't help. I'm very new to OpenSesame so I'm probably doing several things wrong.

My first question is: Are there any differences between sending a trigger via parallel port and sending it via serial port (the answer is probably yes)? Do I have to change my python Code according to this setting?

try:
    from ctypes import windll
    global io
    io = windll.dlportio # requires dlportio.dll !!!
except:
    print 'The parallel port couldnt be opened'

and

global io
trigger = 1
port = 0x378
try:
    io.DlPortWritePortUchar(port, trigger)
except:
    print 'Failed to send trigger!'

Or do I have to use another .dll?

I'm sure, however, that the hardware is working correctly. I was able to send a trigger via HyperTerminal to the NTI and it worked properly. These are the settings I used in HyperTerminal (sorry for the german language version):

There is one last question ... ;-) I checked the port adress of the serial port with a tool called Bios Reader and it showed me the following adress:

So I guess that I have to use the port 0x3F8 instead of 0x378 in the python code, right?

As you see I'm quite confused and any help is appreciated ;-)

Best wishes,

Daniel

sebastiaan · May 2013

Hi Daniel,

My first question is: Are there any differences between sending a trigger via parallel port and sending it via serial port (the answer is probably yes)? Do I have to change my python Code according to this setting?

Yes, the parallel and serial ports require entirely different approaches. Fortunately, the serial port is actually much easier to access, because it doesn't require the use of any external .dll libraries. You can simply rely on the serial module. You can find some examples here:

http://pyserial.sourceforge.net/shortintro.html#opening-serial-ports

In your case, you might open the serial port with a script like this at the start of the experiment:

import serial
exp.serial_port = serial.Serial('COM1') # Can also be COM2, COM3, etc.

And then send a trigger like this (at some moment during a trial):

exp.serial_port.write(chr(1)) # Send the byte 1 as a character

At the end of the experiment, you need to close the connection again (otherwise you may experience trouble running the experiment twice without closing OpenSesame):

exp.serial_port.close()

Good luck!

Cheers,
Sebastiaan

skinnerwinner · May 2013

Hi Sebastiaan,

thanks a lot for your support. It works just fine!

Best wishes,
Daniel

meldiwiny · January 2014

now could any one help me i am using vspe

sebastiaan · January 2014

@meldiwiny

Final warning :-t Please resume with the discussion (one of many) that you have started yourself (here). If you continue to open new discussions and/ or randomly post in old discussions, your account will be suspended.

Gunnar · November 2021

Hi, New user... OpenSesame seems to be a great program. Thanks for sharing! I am trying to get the above in-line-scripting to send signals from OpenSesame to Biopac via a USB TTL Module (Black box toolkit).

I have tried the inlinescripting posted above. However, I am getting an error message:

TypeError exception message: unicode strings are not supported, please encode to bytes:""x01

Could someone advise? Many thanks in advance,

Gunnar

Gunnar · November 2021

Update, solved but other problem arisen.

I tried changing the unicode to bytes, and it seems to have worked as far as the previous particular error message goes. This is the code for triggering now

1 exp.trig.write(0x31)

2 exp.trig.write(0x30)

However, I am not getting a new error message for the inline script controlling the port. I think it is row 3.

1 from serial import Serial

2 exp.trig = Serial('COM3', 115200)

3 exp.cleanup_functions.append(exp.trigger.close)

"in _getattr_ raise AttributeError(u´%s not found´ % var) AttributeError: trigger not found.

Any help would be appreciated, thanks in advance

sebastiaan · November 2021

Hi @Gunnar

The variable is called exp.trig, not exp.trigger.

As an aside, I suspect that this code is based on something that was written a long time ago, when you needed to attach variables as properties to the exp object in order to be able to access them in all scripts. However, this isn't necessary anymore, and you can just use the global variable trig. It won't make any functional difference, but it will make your code a bit cleaner.

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[solved] Sending triggers to Nexus Trigger Interface via serial port

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