Relay Module

Electrically operated switch with normally open and normally closed contacts

Electrically operated switch.

Pins

VCC · power

Supply voltage

GND · ground

Ground

IN · input

Control signal (e.g. from micro-controller)

NC · contact

Normally closed

COM · contact

Common pin

NO · contact

Normally open

Attributes

transistor · string · default: "npn"

“npn” (active-high) or “pnp” (active-low)

Operation

The relay is an electronic switch.

When the IN pin is high / disconnected, COM is connected to NC (NC means normally closed).

When the IN pin is low, COM is connected to NO (NO means normally open).

Setting the “transistor” attribute to “pnp” inverts the logic: when IN is high, COM is connected to NO, and when IN is low / disconnected, COM is connected to NC.

Simulator Examples

• One relay module controlling two LEDs
• Arduino Uno controlling four relay modules