Linescan encoder + triggerstart

What has to be set up to do encoder triggered line aquisition, started by an hardware IO (line input) for a given amount of lines?
I can set rotary encoder as trigger source for single line trigger, yet I lack the defintion of a further IO line trigger to start line grabbing, ending by a desired image height (Dalsa Linea)

EDIT: got it now, using different trigger selectors