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Forum Newbie
Group: Forum Members
Last Login: 2/14/2011 2:55:59 PM
Posts: 1,
Visits: 10
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Hello.
In order to test the time delay between trigger & stimulus, I'm using a simple photodiode taped to monitor --> recording system + trigger sent from Eprime to recording setup.
I'm getting not getting a fixed time delay. Rather, I'm getting 2 fixed time delays that are ~16ms apart (refresh rate=60Hz). So it seems like some triggers are sent one frame early (or late).
I'm using the following inline code to send triggers:
StimlusR.OnsetSignalEnabled = True
StimlusR.OnsetSignalPort = &H378
StimlusR.OnsetSignalData = 255
StimlusR.OffsetSignalEnabled = True
StimlusR.OffsetSignalPort = &H378
StimlusR.OffsetSignalData = 0
I also used writeport and got similar time delays:
WritePort &H378, 0
WritePort &H378, 255
Sleep 50
WritePort &H378, 0
Should I be using something else?
Thanks!
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Junior Member
Group: Forum Members
Last Login: 12/8/2011 1:01:58 PM
Posts: 19,
Visits: 200
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Forum Newbie
Group: Forum Members
Last Login: 3/29/2011 5:03:04 PM
Posts: 5,
Visits: 14
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Did you see this delays in the e-prime output, or on the O-scope? Make sure the refresh rate is really 60Hz but not 59.6 or so. What is the duration of the Stimuli?
And do you think sending 255 versus 0 may cause small timing difference in the preparation of these triggers? Is there a test showing delays in parallel port send?
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