In ladder logic programming, how are outputs represented?

In ladder logic programming, outputs are represented using coil symbols. These symbols visually depict outputs or the controlling devices that are activated by the logic in the rung they appear on. A coil symbol typically resembles a circle and is often associated with devices like relays, solenoids, or illuminated outputs that are controlled by the ladder logic program. When the conditions preceding the coil in the rung (using contacts) are met, the coil is energized, activating the corresponding output device.

Coil symbols are crucial for establishing the actions taken by the programmable logic controller (PLC) based on input conditions defined elsewhere in the ladder logic. This makes them integral to the operation of automation systems, as they directly represent the outputs that affect physical processes within a control system.

In contrast, relay symbols, contact symbols, and indicator lights serve different purposes in ladder logic diagrams. Relay symbols represent the mechanical relays within the control circuit, contact symbols denote inputs or conditions that must be satisfied to achieve a certain state, and indicator lights are used to visually signify the status of a particular output but do not represent the output control logic itself. Thus, the correct representation for outputs in ladder logic is the coil symbol.