Neuroscan/E-Prime Buffer

[Michiel Spape]

Hi,
One thing to add to what has already been said: are we talking about error: overflow, or error: buffer overflow?
The former is generally really simply helped, it tends to be caused by a variable defined as integer but then getting a long number assigned to it, for instance:
Dim a As Variant
Dim i As Integer
i = -32768
a = Abs(i)                                                       'Result is a Long.
i = Abs(i)                                                        'Overflow!
(from ebasic help)
That is, an integer can only have values assigned to it between -32768 and (+)32767, thus assigning Abs(-32768) [results in +32768) causes an overflow. This would explain your scenario as follows: you have, for instance, a cumulative reaction time (or the sum of RTs), which sooner (if participants are really slow) or later (if they aren't) causes the overflow by reaching higher than 32767. Personally, I often get this because I define a variable as integer and do constant clock.read (which gets the time in ms from the onset of the experiment). This causes an overflow after less than a minute.  Anyway, the error can usually be solved by defining the variable as long (or variant, but a curse rests on such ill-defined types) instead of integer.

The latter (buffer overflow) is presumably associated with your neuroscan setup, which, I would expect, uses serial port communication. I would have predicted that something like 'flushoutputbuffer' might have helped you, but, according to the help file:
"This function is reserved for future use.  Serial output communications are synchronous.  Data is always flushed from the output buffer after write operations are called."
Did the future come with E-Prime 2? Are you using E-Prime 2?

Best,
Mich


Michiel Spapé
Research Fellow
Perception & Action group
University of Nottingham
School of Psychology
www.cognitology.eu

From: e-prime at googlegroups.com [mailto:e-prime at googlegroups.com] On Behalf Of ben robinson
Sent: 30 November 2010 20:20
To: e-prime at googlegroups.com
Subject: Re: Neuroscan/E-Prime Buffer

which program is giving you the "Buffer Overflow" error, eprime or neuroscan?  if eprime, does eprime crash when the error occurs?  can you see where you were in the script when i crashes, and does it always crash at the same place in the script?
On Tue, Nov 30, 2010 at 11:50 AM, Jessica Miller <jess.cogneuro at gmail.com<mailto:jess.cogneuro at gmail.com>> wrote:
Hello!

We have Neuroscan 4.5 collecting ERP data while E-Prime presents the
experiment to participants. Recently we have been getting a "Buffer
Overflow" error message as soon as 15 minutes into an experiment and
as late as 1 hour 20 minutes. I am wondering if anyone else has had
this problem and if it is a problem with the data being sent from E-
Prime to Neuroscan, or if it is another problem. Both computers that
we use meet all requirements for both software packages, and were
fully upgraded (RAM, video memory, etc) in the last month.

Any suggestions would be much appreciated.

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