Using this BK Precision 1856D frequency counter is quite simple. First, make sure you have connected it to the correct power supply that comes with it. Then, you can start measuring frequency, period, or totalizing depending on your needs. Just follow the basic operation instructions on the device. When using it, keep it away from extreme temperatures and humidity. Also, avoid dropping or knocking it around. For maintenance, regularly check the power supply and the connections. If there are any signs of damage, stop using it and get it checked by a professional.