Sending TTL signals to ASL eyetracker (case 16133)

[daniellecornish]

Hi,
I have been trying to send TTL signals from DirectRT on one computer to ASL's EyeTrac 6 on a second computer, to segment the pupil diameter data in sync with the stimulus presentations. The I/O test worked, and the byte value changed, indicating that the ttl signal is being sent. However, when collecting the data the XDAT value does not change from 0 and so I can only get one continuous stream of unsegmented data. I set up the csv file as per the sample but am unsure which TTL and time values are best (as another post stated that TTLs must be brief pulses?).
Thanks!