21.8 SUMMARY
A/D conversion will convert a continuous value to an integer value.
D/A conversion is easier and faster and will convert a digital value to an analog value.
Resolution limits the accuracy of A/D and D/A converters.
Sampling too slowly will alias the real signal.
Analog inputs are sensitive to noise.
The analog I/O cards are configured with a few words of memory.
BTW and BTR functions are needed to communicate with the analog I/O cards.