pinout
The manner in which an electrical connector or device is wired; the list of signals that correspond to each pin or output.
pinout: the map of which wire goes where
A pinout is a documented assignment of electrical signals to the physical pins on a connector, integrated circuit, or device. It tells you which pin carries power, which carries ground, which carries data, and so on. Without a pinout diagram or table, you cannot reliably connect equipment or diagnose faults.
Pinouts vary widely by connector type and device function. A DB-9 serial connector has 9 pins; a micro-USB has 5. An integrated circuit might have 8, 40, or 400 pins arranged in rows. The physical order of pins on the device does not follow any universal standard. Pin 1 might deliver +5 volts on one device and ground on another. This is why every piece of equipment comes with a pinout diagram: guessing leads to short circuits, failed communications, or destroyed components.
Industrial pinouts are critical in field wiring. A factory technician connecting a limit switch to a PLC input must match the switch's output pin to the correct terminal on the controller. Reversing power and ground will burn out the input circuit. Connecting a signal line to the wrong pin silently produces wrong readings. Many industrial connectors use keyed or polarized designs to prevent backward insertion, but this only protects against rotation, not against wiring the wrong internal conductors.
Finding and using pinout information
Pinout data appears in device manuals, on silkscreen labels printed directly onto circuit boards, and in online datasheets maintained by manufacturers. For legacy or discontinued equipment, pinout information may be scarce or absent. Industrial electricians often reverse-engineer pinouts using a multimeter and careful tracing of internal wiring, or consult equipment schematics if available.
The term "pinout" originated from early electronic design when devices were literal pins protruding from a component body. Today it is used even for fully integrated or wireless systems where no physical pins exist. The word persists because the concept remains unchanged: a defined correspondence between signal names and physical connection points.