After you create a local or global variable, you can read data from a variable or write data to it. By default, a new variable receives data. This kind of variable works as an indicator and is a write local or global variable. You also can configure a variable to behave as a data source, or a read local or global variable.

On the block diagram, you can distinguish read local or global variables from write local or global variables the same way you distinguish controls from indicators. A read local or global variable has a thick border similar to a control. A write local or global variable has a thin border similar to an indicator.

Tip Write a value to a global variable before reading from it so that it has a known initial value when you access it.