The voltmeter measures the voltages present in a circuit at specific points.

Choose a node to for the positive and negative nodes using the drop down box or by using the "Probe" tool next to the drop down boxes. Using the probe tool and clicking on a node that you would like to measure automatically selects that node in the drop down box. You should also be aware that voltmeter instruments are automatically inserted if you place a voltmeter part in the schematic.

The meter displays its voltage measurements in two ways: text and a moving bar graph. The bar’s length expands and contracts with the voltage being measured, which makes it an analog readout. When the measured voltage exceeds the voltmeter’s range, the bar changes color from its normal blue to red. Pressing the “Auto” button overrides the fixed range and auto adjusts the range to twice the highest voltage reading it sees.

If the signal is AC, then choose whether the RMS (Root Mean Square) value should be used or the peak value. Then select the period over which the voltmeter measures.
Pressing the “Setup” button toggles the height of the voltmeter, so that when its setup is complete, the voltmeter becomes only as tall as its display band. Note that a voltmeter virtual instrument is automatically inserted if a voltmeter part is placed in the circuit.