[pin_not_connected]
KiCad's Schematic Editor emits the [pin_not_connected] ERC diagnostic when a symbol pin is left floating without an explicit wire, label, or 'No Connect' flag.
The `[pin_not_connected]` Electrical Rule Check (ERC) diagnostic in KiCad's Schematic Editor indicates that a component symbol's pin has no electrical connection to any net, wire, label, or power symbol within the schematic design. Furthermore, the pin lacks an explicit 'No Connect' flag, which is required to tell the ERC engine that leaving the terminal open is intentional.
KiCad enforces a rule that every active pin on a schematic symbol must be explicitly handled by the designer to ensure connectivity intentions are clear. When the ERC engine scans the schematic, it verifies the connectivity of all symbol pins. If it encounters a pin terminal that does not intersect a valid net (such as a wire, bus, or global/local label) and has not been explicitly marked with a 'No Connect' directive, it raises this condition as a schematic violation. The severity of this violation is typically an Error by default, but it can be adjusted in the Violation Severity panel within the Schematic Setup.
Symbol: R (Resistor) Pin 1: Unconnected Pin 2: Unconnected (No 'X' No-Connect flags applied)
Attach a valid net to the pin, or explicitly mark it as intentionally floating using a 'No Connect' flag. ```KiCad Schematic Symbol: R (Resistor) Pin 1: Unconnected, but explicitly marked with a 'No Connect' (X) flag. Pin 2: Unconnected, but explicitly marked with a 'No Connect' (X) flag. ```