There are examples for image acquisition available at \\National Instruments\LabVIEW\Examples\Imaq. There must be a llb which calls "Signal I/O.llb" or something like that. In that library you should find examples for triggerd acquisition. That VI uses a function calls "IMAQ Configure Trigger". This function has got an input to set the trigger mode "trigger each line". Others are "start acquisition", "each buffer", "each buffer list" etc. If you can not find "trigger each line" then delete the control/constant and recreate it.
Use the IMAQ-D6804 cable and connect you trigger signal to it.
You need a camera file (*.icd) where is a string inside to let the camera that it has to send a signal to the camera if the grabber gets your trigger signal. If you need an exam
ple icd-file. Visit ni.com/camera and take a look into the camerafile of the Basler L101.
Hope this helps.