What is the difference between On/Off, Floating and Modulating Control?

On/Off Control (2-point control):

The basic type of control in a control loop. There are only two stages: OPEN or CLOSE. The actuator drives the damper either to its fully open position, or to its full closed position.

Floating Control (3-point control):

Floating Control is a variation of ON/OFF Control. There are three stages: OPEN, STOP & CLOSE. The actuator must use 2 inputs from the controller: CW(clockwise) & CCW(counter-clockwise). One INPUT(CW) drives to its fully open position, while other INPUT(CCW) drives to its fully closed position, and if there is no signal on both INPUTs, the actuator stops and maintains its position.

Modulating Control (Proportional control):

Provide a higher end of positioning control. The actuator varies proportionally with the analogue signal from the controller. The control system produces a control signal from 0% up to 100% to deliver the necessary output power to the actuator to move proportional to the control signal. Proportional control signals are usually in the range of voltage 0-10V, 2-10V or current 0-20mA, 4-20mA.