DIutgång

DIutgång, or digital output, is a channel in electronic control systems that transmits a binary signal from a controller to an external device. It is the counterpart to a digital input (DI) and is used to switch devices on or off, such as relays, lamps, valve coils, or motor starters. Each DIutgång typically represents a single on/off point in a larger control network.

Digital outputs come in two broad electrical styles: relay outputs and transistor outputs. Relay outputs use electromechanical relays to switch loads and provide galvanic isolation between the controller and the load. Transistor outputs, including solid-state or MOSFET-based types, switch loads directly and are usually faster and have longer lifetimes for signaling tasks. Outputs can be configured as sourcing (high-side) or sinking (low-side). In a sourcing arrangement, the output supplies current to the load from the power rail; in a sinking arrangement, the load returns current through the output to ground.

Electrical characteristics vary by system. Common supply voltages for industrial DIutgångs are 24V DC, but 5V or 12V may also be used. Current ratings differ, from modest signaling currents to higher values needed for coils and small actuators. Many modules offer galvanic isolation to protect the controller, and some include protective features such as short-circuit protection and fusing. When driving inductive loads (coils, relays), a flyback diode or other suppression method is typically required to protect the output device.

In practice, a DIutgång is controlled by software to set the output high or low. Example uses include energizing a contactor to start a motor, lighting an indicator lamp, or opening a valve. Standards relevant to digital outputs in industrial environments include IEC 61131-2 for programmable controller I/O and EN 60204 for machinery safety.