Since your question actually deals with the functions and operations of the 6713 board, this question actually belongs in the Measurement Hardware category of the Developers Exchange. In the future, you will find similar questions and be exposed to other users of this product more likely by posting over there.
The retriggerable pulse generation is a built-in feature with the DAQ-STC chip. You can do this with the example that ships with NI-DAQ located in the LabVIEW >> Examples >> Daq >> Counter >> DAQ-STC directory. It's called Generate Retriggerable Pulse (DAQ-STC).