delcasmx,
I have attached a screenshot of a similiar architecture that you could utilize with lower level DAQmx VIs. Basically, you would have to place the DAQmx Start.vi for the Input before that of the output. This can be done by wiring the error cluster to control the data flow. You may also want to use a reference trigger in which the output triggers the input of the other card. Instead of taking only post trigger samples, you could also obtain a certain amount of pretrigger samples to ensure that you do not miss your signals. I have also included two documents which will provide more details into pretrigger samples.
<a href="http://zone.ni.com/devzone/cda/tut/p/id/5014" target="_blank">Waveform Acquisition with an External Trigger and Pretrigger Scans</a> <a href="http://zone.ni.com/devzone/cda/tut/p/id/5014" target="_blank"></a>
<a href="http://zone.ni.com/devzone/cda/tut/p/id/2121" target="_blank">pretriggering</a>
Start Order1.GIF:
http://forums.ni.com/attachments/ni/250/41748/1/Start Order1.GIF