• 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 for older PLCs such as the PLC-5s.

• Analog shielding should be used to improve the quality of electrical signals.