Thanks for the responses, the typical values that exhibit a problem are

HEAD_OUT = 101
FUNC_OUT = 38
PAN_OUT = 0
TILT_OUT = 0
ZOOM_OUT = 1
FOCUS_OUT = 6

ERROR_OUT should calculate as 109 but the ERROR_OUT is 45?
All values are decimal.
All variables are bytes.
Array DATA_OUT has 15 elements