I read that in almost all daq board datasheets the analog inputs are specified as single ended or differential inputs.
But the same daq have digital I/O ports. How can one understand whether the digital input is differential ended or single-ended. Or are the default one of them?
For example from a manual:
16 single-ended (SE) or eight differential (DIFF) analog input channels
Eight individually configurable digital I/O channels
As you see the differential or single input nature of the analog inputs are specified. But for digital inputs no information.
How is CM noise for a digital signal rejected ?
Which one of the opamp represents digital input?:
The black is the pulse waveform below, and the red is the noise superimposed on it. So if the system were diff ended and inputs were diff ended the red CM noise would be rejected. But for digital inputs red will never be rejected since it is swinging between the thresholds?: