TTL pulse

[David Moore]

Hi David,

Thanks for your advice, I have tried what you have suggested however I 
still don't seem to be getting a pulse. Can you suggest what the settings 
in the parallel port menu or how to set all bits to 0 at the beginning (I 
have put an inline at the beginning with WritePort &H378, 0 in.

Thanks Dave

--On 08 April 2009 11:32 -0400 David McFarlane <mcfarla9 at msu.edu> wrote:

>
> At 4/6/2009 04:27 AM Monday, David Moore wrote:
>> Dear all,
>>
>> I've written a script to present attentional tasks to participants
>> however I need to send a TTL pulse to an external device at random
>> intervals.
>>
>> I'm using eprime 2 and I have added the parallel port in the devices and
>> left the standard settings. I've then put in an inline with the command
>> WritePort &H378, 255 however I am not getting any pulse.
>>
>> Can anyone help?
>>
>> Dave
>
> To send a pulse, you must both turn the pulse on and then turn it
> off, with some duration in between.  WritePort &H378, 255 will just
> set all bits to 1, you still need to wait a moment and then send them
> back to 0.  Something like this:
>
> WritePort &H378, 255  ' all bits to 1
> Sleep 20  ' wait 20 ms
> WritePort &H378, 0  ' all bits back to 0
>
> Of course, you should first initialize all bits to 0 way at the start
> of your program.  And this assumes that &H378 is the correct port for
> your case, you may need to contact your IT staff to verify
> that.  Finally, I think PST has a sample program at their website
> that you can download to demonstrate some of this.
>
> -- David McFarlane, Professional Faultfinder
>
>
> >





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