Acquiring TTL Digital Signal With NI-9361 in LabVIEW

Updated Apr 21, 2023

Reported In


  • NI-9361


  • LabVIEW

Issue Details

I have a sensor that generates a TTL pulse train signal. 
How to connect my TTL signal to the 9361?
How to configure it in LabVIEW?


Based on the NI 9361 getting started guide:

"Connecting Single-Ended Devices
You can connect single-ended devices, such as TTL or CMOS to the NI 9361. For single-ended connections, connect the device out to the DI+ terminal on the NI 9361. Do not connect the DI- terminal on the NI 9361 for single-ended connections."

In LabVIEW, you will need to configure the measurement method of the DAQmx Create Virtual Channel >> CI Freq VI as Dynamic Averaging


Additional Information

The NI 9361 measures the difference between the DI+ and DI- terminals to determine if that difference is greater or less than the digital logic levels. If the difference between the terminals is within the input high range, the channel registers as high. If the difference between the terminals is within the input low range, the channel registers as low.

If your digital signal has noises, the NI 9361 has a digital filter on each of the digital input lines to filter unwanted glitches on the digital input signal.