Panel meters are instruments that display a visual representation of an input signal using an analog needle or other physical indicator or digital characters. Many panel meters also include auxiliary outputs that may be used for alarm options as well as the ability to transfer data or a reference signal to a computer or microcontroller. Panel meters are selected by measuring range, display type, character/indicator attributes and supply voltage. Meters types include current, voltage, frequency, process, resistance, temperature, and wattage.