looping trials

Greetings,

I'd like to build an input file such that DirectRT will continually repeat rows containing stimlists until DirectRT recieves a TTL signal to stop. Something like in the picture below:

[IMG]http://i96.photobucket.com/albums/l184/Justinpublic/directRT.jpg[/IMG]The purpose is to create a secondary task for driving a scenario in a simulator. I'd like the secondary task (created within directRT) to run as soon as the simulator tells it to start and stop when the simulator tells it to. This secondary task will be self-paced, such that participants could complete as many as possible within the duration of the scenario.I was thinking I could create a bunch of rows (hundreds of them) and have a conditional ttl signal for each row that would skip to the a row that closes directrt when the simulator sends a signal to stop. would that work? I'm not sure how to put it in.
Any ideas?