The AND Gate

A basic AND gate consists of two inputs and an output. If the two inputs

are A and B, the output (often called Q) is “on” only if both A and B are

also “on.”

In digital electronics, the on state is often represented by a 1 and the off state

by a 0. The relationship between the input signals and the output signals is

often summarized in a truth table, which is a tabulation of all possible inputs

and the resulting outputs. For the AND gate, there are four possible

combinations of input states: A=0, B=0; A=0, B=1; A=1, B=0; and A=1, B=1.

In the following truth table, these are listed in the left and middle columns.

The AND gate output is listed in the right column.

Table 1Truth Table for AND Gate

A	B	Q=A AND B
0	0	0
0	1	0
1	0	0
1	1	1

In LabVIEW, you can specify a digital logic input by toggling a Boolean

switch; a Boolean LED indicator can indicate an output. Because the AND

gate is provided as a basic built-in LabVIEW function, you can easily wire

two switches to the gate inputs and an indicator LED to the output to

produce a simple VI that demonstrates the AND gate.

                      Figure 1 LabVIEW AND Function Wired to I/O Terminal Boxes

Run AND gate.vi from the Chap 1.llb VI library. Push the two input buttons

and note how the output indicator changes. Verify the above truth table.