The Expression Node in LabVIEW calculates expressions that contain a single variable. Use expression nodes to simplify the calculation of single-variable expressions that are complicated to implement with other LabVIEW functions.

An Expression Node has a single input terminal. Expression Nodes use the value you pass to the input terminal as the value of the single variable in the expression. The output terminal returns the value of the calculation.

For example, consider this simple expression:

x × x + 33 × x + 5

The block diagram in Figure 10. Expression with LabVIEW Functions uses Numeric LabVIEW functions to represent this expression.

Figure 10. Expression with LabVIEW Functions

Use an Expression Node, as shown in Figure 11. Expression with Expression Node, to create a much simpler block diagram for the same calculation.

Figure 11. Expression with Expression Node

Polymorphism in Expression Nodes

The input terminal of an Expression Node is the same data type as the control or constant you wire to it. The output terminal is the same data type as the input terminal.

An Expression Node supports the following input data types:

  • Any non-complex scalar number
  • Any array of non-complex scalar numbers
  • Any cluster of non-complex scalar numbers

With arrays and clusters, the expression node applies the expression to each element of an input array or cluster.