What you need to do is find the examples that ship with the Labjack driver, and I'll bet the answer will be there.
The general concept is to use the pulses from your tach as the gate for a counter whose source is attached to a known-frequency signal. See
Period Measurement with a Counter" for more info.
This is a very straightforward concept; any difficulty will come with configuring the counter appropriately and communicating with it via software to get meaningful results. This is where Labjack and its software comes into play, and I would be surprised if there wasn't already a measure-frequency LabVIEW example that is bundled together with their driver. The problem is that few people on this forum has used a Labjack device.
I've remember someone saying that the Labjack support is good, so if you can't find an example, you ought to try out the forum they have on
their site.
Regards,
John
Message Edited by Johnner on 04-05-2005 09:38 PM