So below is a sample of the Greater and Equal than function
M8000 is a always on bit in the PLC. As long as the PLC is in run mode this bit will be on.
D1 in my example will be from you analog
D0 is your setpoint
M5 is your output
So when D1 is equal or greater than D0, M5 will be high. When D1's value goes below D0 setpoint value, M5 will be low