Sample Clock

Your device uses a sample clock to control the rate at which samples are acquired and generated. This sample clock sets the time interval between samples. Each tick of this clock initiates the acquisition or generation of one sample per channel. In Traditional NI-DAQ (Legacy), the sample clock is called the scan clock or the scan interval counter. You also can connect an outside source as your clock. In software, you can specify the interval (how fast the clock acquires or generates signals) by specifying the sample rate, which is called the scan rate or update rate in Traditional NI-DAQ (Legacy). You can limit the sample rate by the signal conditioning you apply to the signals or the number of channels in your application. However, the number of channels affects your measurement only if you are sampling close to the maximum sample rate for your device.

Note  Sample clock timing for digital I/O is not supported on all devices.