Losing ERP triggers with E-Prime

[Tony Zuccolotto]

Richard,

This would seem to be a good way to do this, but I would suggest using
Clock.Read instead of Timer (e.g. Clock.Read uses E-Prime's real-time
clock, but Timer just uses the system clock and is mainly there for
backward compatibility of some early language features of VisualBasic).

In theory though you should also just be able to do
 	WritePort &H0378, 1
	Sleep 100
	WritePort &H0378, 0
	
(Sleep is also implemented internally using the real-time clock).

Is there any chance this is perhaps a problem with the configuration
mode of the parallel port in the BIOS?   What choices are listed for
parallel port modes in your BIOS and what is the current setting that
you are using?

Thanks,
Tony


> -----Original Message-----
> From: Don.Rojas at UCHSC.edu [mailto:Don.Rojas at UCHSC.edu]
> Sent: Friday, November 14, 2003 6:12 PM
> To: eprime at mail.talkbank.org
> Subject: RE: Losing ERP triggers with E-Prime
> 
> Yes, it might be viable.  If you are using a Writeport command, you
need
> to leave whatever parallel port bits you are toggling on for a while
> before writing zeros to the port to turn off the trigger.  How long
the
> trigger needs to be depends on your specific acquisition, but 30 to 50
> ms is usually ok with our Neuroscan EEG acquisitions.  Try using an
> in-line trigger sequence like this:
> 
> TimerDuration = .03
> StartTime = Timer
> 
> do
> 	WritePort &H0378, 1
> Loop Until Timer > StartTime + TimerDuration
> 
> WritePort &H0378, 0
> 
> 
> -----Original Message-----
> From: eprime at mail.talkbank.org [mailto:eprime at mail.talkbank.org] On
> Behalf Of Richard P. Heitz
> Sent: Friday, November 14, 2003 3:12 PM
> To: E-Prime Listserv
> Subject: Losing ERP triggers with E-Prime
> 
> That makes sense, but unfortunately, I am not using pre-release, nor
is
> the
> response period any where near the display stimuli (temporally, that
> is).
> To further explore the problem, I wrote a simple program in E-Prime
> using
> the writeport command and an identical program in Presentation.
> Presentation lost no triggers whereas E-Prime lost 7%, again randomly.
> So,
> I figure it has to be something about the way E-Prime is writing to
the
> parallel port.  Is my earlier speculation about a "pulse width" even
> viable?
> 
> 
> 
>