This example shows how to acquire clocked digital data using an external clock provided at the CompactDAQ chassis PFI terminal. It uses a cDAQ 9178 chassis and NI 9402 module with ID cDAQ2Mod3. A digital signal is connected to the module PFI0 terminal to provide a scan clock.
Create a DataAcquisition object and add the digital input line.
d = daq("ni"); addinput(d,"cDAQ2Mod3","Port0/Line0","Digital");
Add a clock specifying source and destination. Then set the DataAcquisition scan rate to match the external clock frequency.
addclock(d,"ScanClock","External","cDAQ2/PFI0"); d.Rate = 100e3;
Acquire and plot the digital input data.
[data,timestamps] = read(d,seconds(1),"OutputFormat","Matrix"); plot(timestamps,data(1:100,1))