Campbell Scientific CPEC200 Closed-Path Eddy-Covariance System - Manual (Page 90)

Appendix D. Control Bits
If ControlBits is greater than 255, this indicates bit 9 of ControlBits is set.
This means the sample pump heater is on. To decode other temperature control
bits, subtract 256 from ControlBits and compare the remainder to the bit
values below.
If ControlBits is greater than 127, this indicates bit 8 of ControlBits is set.
This means the valve module fan is on. To decode other temperature control
bits, subtract 128 from ControlBits and compare the remainder to the bit
values below.
If ControlBits is equal to 64, this indicates bit 7 of ControlBits is set. This
means the valve module heater is on.
D-2