USB is particularly sensitive to inductive loads. USB establishes high-speed communications with the motherboard of your PC. If an error is presented on the USB port, the motherboard of your computer will disconnect the device from the operating system. In the case of USB relay controllers, you will lose communications until the device is unplugged from the USB port and plugged back in. When working with USB communications in combination with inductive loads, it is absolutely essential that induction suppression capacitors are used to help prevent loss of communications. Even with these capacitors in place, the possibility does exist that capacitors will not suppress enough induction to prevent periodic communications loss.