Triggering frequency measurement with 9402 and cDAQ

[iyeager]

Hi all,

I'm trying to take a speed measurement off of a shaft using a hall effect sensor and a 9402 module in a 4 module cDAQ 9174 chassis. I've used the low frequency measurement example using DAQmx but if the shaft isn't spinning I get a timeout error.

Two questions, is there a way to use the Express VI's to accomplish this and how do I create a trigger to start the measurement?

-Ian

[falkpl]

Why not clear the timeout and report 0 RPM.  The timeout is 0 rmp but you dont want to wait forever and block program flow.

[iyeager]

Yes, that is exactly what I'd like to do but how can it be achieved without causing the program to hang?

-Ian

[falkpl]

In the read, specify a timeout.  the read will return and not block.