ON/OFF ControllerLiquid level control methods range from relatively simple and inexpensive ON/OFF control methods to more complex closed loop systems. The ON/OFF control methods can use discrete devices like relays and have discrete inputs and outputs or they can use an analog input from a sensor and provide a discrete output. However, these methods can only control the level between a high and low limit. The more complex closed loop systems use analog inputs and outputs so that they can control the level at any point. In this page will show how to perform ON/OFF liquid level control using control relays and a process meter's discrete outputs. |