Hello alextroy, Depending on what NI hardware you have (and what type of tachometer), you probably want to use one of our counter tasks to accomplish your goal. Specifically a period task or a frequency task would be ideal. You can also use an analog tachometer as well. The trick is that you need a card that has a counter for the counter task or a hardware timed analog input for the analog tach. From your previous posts, it appears that you are using a USB-6008 which is static timed only. The reason static timing will not work for us is that it's sampling is not very accurate in time (being software timed). The example we always use around here is if your virus scan kicks on, it can cause a change in your sampling rate because your CPU has more to do. If you are measuring slow signals, this may not be a problem, but it is something you should consider.The big thing it sounds like you are looking for is our <a href="http://www.ni.com/soundandvibration/" target="_blank">Sound and Vibration</a> Toolkit. This is an addon to LabVIEW that has a ton of analysis VI's that sound perfect for your application. It includes an entire folder of order analysis VI's that do order tracking and analysis as well as an entire folder of VI's for Tachometer Processing. Below are a couple of links that should help you get started with programming as well. Please let me know if you have any questions.<a href="http://digital.ni.com/manuals.nsf/websearch/44D6FD85880DAF80862572FE0077A0AF" target="_blank">DAQ Getting Started Guide</a> <a href="http://zone.ni.com/devzone/cda/tut/p/id/5434" target="_blank">Getting Started with DAQmx</a> <a href="http://zone.ni.com/devzone/cda/tut/p/id/5468" target="_blank">Getting Started with NI-DAQmx: Getting Started with NI-DAQmx Programming in LabVIEW</a> <a href="http://zone.ni.com/devzone/cda/tut/p/id/2835" target="_blank">Learn 10 Functions in NI-DAQmx and Handle 80 Percent of Your Data Acquisition Applications</a>