USB-RLY02 is a 2 relay driver circuit with power up to 16 amps which is connected via a USB bus and controlled from any application that sends data over a serial port. With this circuit can control up to 2 relays independently from any PC. The circuit has 2 relays of 1 circuit and two positions that can be controlled by commands sent from the PC. The circuit includes a converter USB to serial chip, so from the point of view of programming, all you have to do is send the desired control data to a serial port. This means that any program that sends data over a serial port, can control the drive circuit and the relays as desired. The circuit is powered directly from the USB bus, so no need power supply for operation. This circuit is functionally identical to the USB-RLY16 but with only 2 relays. The USB-RLY02 has a LED placed next to each relay to indicate the status. When the LED is lit, the relay is actuated. If the voltage and current in the relay contacts remains within the area of the line graph below, the relay will function correctly throughout their life cycle . If the voltage or current exceed the safe zone , the life of the relay will be shortened significantly .