I have a few external input probes on a device I'm making which are connected to an ADC. Is there an electrical (i.e. non-mechanical) method of detecting whether the ADC input is floating/disconnected/tristate or actually connected to a signal source, without altering the input signal? The signal should be considered analog; not necessarily a digital logic signal.
The purpose is to ascertain whether the ADC data being read is significant or not, so that the gaps when the probe is disconnected can be noted with respect to time.