Can I measure frequency with a SCXI-1120 module and SCXI-1320 terminal block?

[MBS]

I am attempting to measure a square wave from a directional encoder to display RPM of a dynamometer. The waveform will have a frequency of 0-4KHz, with 3.6KHz being nominal, at about 5volts RMS. How can I measure the frequency of this waveform with the hardware I am currently using? In addition to what is listed above, I am using a PCI6034E GPIB card and LabView software.

[Annette Perez]

In order to measure frequency, I would not recommend to use the SCXI-1120, but the SCXI 1126, which is a programmable isolated F-to-V module.

If by any reason you do not want to use SCXI-1126, then I would suggest to use the counter/timers of your board. The counter/timers are TTL compatible, and are the devices that we mostly recommend for doing precise frequency measurements.

In order to have access to the counter/timers of your board through your SCXI chassis, you will need SCXI-1180, which is basically a feedtrhough panel for your DAQ board.

Once we have access to the counter/timers through the SCXI chassis, we can proceed with the coding.

I found a pretty good webpage that clearly explains how to perform frequency measurement with the DAQ-S
TC counter/timers (DAQ-STC is the type of counter/timer chip that you DAQ device has). Here is the link to it:

Pulse Width & Frequency Measurements


As you will see, this link contains tutorials, application notes and example programs. I would recommend to pay special attention to the example program called: DAQ-STC: Measuring frequency.

Good luck with your application!