How Do You Wire Using Ladder Logic?
Ladder logic is a method of designing circuits using a combination of switches and relays to implement a logical expression. It is useful for constructing simple control circuits that use electromechanical devices for the logic. The method involves writing a Boolean expression for the required function and then translating it into a physical design with a layout that resembles a ladder. The rails of the ladder are system power and ground, and the control and operational elements are the rungs. Terms in the logical expression are switching devices, and the output is usually an indicator or a relay coil that energizes another device. Write a Boolean expression for the required control function. EXAMPLE: Design a circuit that will run a cooling fan when a circuit board is hot and the access door is closed. It must also run the fan if the TEST button is pressed and the access door is closed. This translates to the expression: Run fan = (A AND B) OR (C AND B) where: A represents a hot circu
