SCXI-1126 Reading a TTL Signal

[KyleF]

I have a TTL signal that is coming into the SCXI-1126 and I am trying to read the frequency.  The frequency that it is reading is at 173 Hz and have measured it with a scope to be 43Hz.  What do I need to do in order to read the TTL Signal’s frequency?  I have tried to setting the threshold to 1V and that did not work.

Thank you for all of your help

[Raajit_Lall]

Hello Kyle,

Are you reading these values in Measurement and Automation Explorer (MAX) or in LabVIEW?  Can you set up a task for frequency measurement in MAX and do you still get the wrong frequency reading?  For your TTL signal, do you know what the rise time and the fall time are?  It would also help if you provided information about the data acquistion card that you are using and whether you are using DAQmx or Traditional DAQ as your driver.

Here is an online Developer Zone article that has an example which shows how to measure frequency on an SCXI-1126 using Traditional DAQ.

Measuring Frequency into an acquisition buffer using an SCXI-1126

Best Regards,