Romek,
As stated by a previous reply, this can all be done in LabVIEW. Take a look at the two Knowledge Base articles I have linked below.
How Can I Start and Stop an Analog Acquisition Using an Analog Trigger?
http://digital.ni.com/public.nsf/websearch/8737E90ABEE342BD862569EE0077F6D2?OpenDocument
[Analog Input] Start and Stop Triggers, External Gating
http://digital.ni.com/public.nsf/websearch/862567530005F09C86256755004A1F21?OpenDocument
The first article may be of the most use to you.
Regards,
Justin Britten