How do I convert optical sensor pulses from NI9220 to rpm or speed?

[RonSS]

We are running a test using Signal Express to capture data. There are two inputs from optical sensors for engine speed and wheel speed. The optical sensors will be sending pulses (equivalent to the input voltage of approximately 12 volts) to an NI 9220, Once we have the data, it will contain pulses over a period of time. It appears that Signal Express can convert the pulses to speed or rpm with a post processing of analog signals, but I have not been able to figure out how to do it. Any help would be greatly appreciated. Thanks.

[Wild_man]

Ron,

Typically when measuring rotational speed with a sensor such as yours a counter module would be used. Counter modules support frequency tasks. The frequeency output of the counter task can then be used to easily calculate the rotational speed.

Also, you mention that this is a 0-12V signal but the module you mention, the NI9220, is only rated for plus or minus 10V.  

Thanks,