TTYL signal problems

[SIZE=2]Hello,[/SIZE]
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[SIZE=2]I am able to play video files in DirectRT. However, I need the DirectRT to send a TTYL signal when the video begins because I am recording physiological data and need a reference point for my data analysis. As I only have 2 short video clips, I only need 2 TTYL signals. [/SIZE]
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[SIZE=2]For some reason, DRT is not sending the signals properly. [/SIZE]
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[SIZE=2]If I restart the PC on which the DRT is running and then start the DRT program with the video clips, it will send a TTYL signal. After sending this first signal, however, it will send no signals thereafter. [/SIZE]
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[SIZE=2]Each video clip has its own input file and is run independently (as DRT would not run the 2 clips in the same input file). Any clues as to why I'm having this problem? [/SIZE]
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[SIZE=2]I've checked the input files and there appears to be no problem there. Besides, I can get one signal using either one of the input files after restarting my PC (which means it is reading the files properly).[/SIZE]
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[SIZE=2]I've also tried using a different computer with DRT and still had the same problem. [/SIZE]
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[SIZE=2]I've checked Ethernet cord that runs from my Biopac software to the PC that records my physiological data and there is no problem there. I also checked the cord that sends the TTYL signal (that looks almost like a printer cable) and it works properly. [/SIZE]
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[SIZE=2]Can you help me? [/SIZE]
[SIZE=2]Thank you![/SIZE]
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