• The return value is 2 bytes wide unsigned CO concentration value, the unit is 1 ppm, the resolution is 0.01 ppm (10 ppb), and the range from 0.00 ppm to 655.34 ppm. Value 0xFFFF (i.e. 655.35 ppm) specifies a sensor error.
• FRC 2-byte: FRC return value is the CO concentration value +4 (i.e. 0x00A4 = 164 is 1.60 ppm). Because of FRC predefined values the raw values from 0xFFFC to 0xFFFF (i.e. 655.32 ppm to 655.35 ppm) cannot be passed.