1.3 Block diagram  (Page 2/3)

Expandable nodes versus icons

You can display VIs and Express VIs as icons or as expandable nodes. Expandable nodes appear as iconssurrounded by a colored field. SubVIs appear with a yellow field, and Express VIs appear with a blue field. Use icons,such as the Basic Function Generator VI icon if you want to conserve space on the block diagram. Useexpandable nodes, such as the Basic Function Generator VI expandable node to make wiring easier and to aid in documenting block diagrams. By default, subVIsappear as icons on the block diagram, and Express VIs appear as expandable nodes.

To display a subVI or Express VI as an expandable node, right-click the subVI or Express VI and select View As Icon from the shortcut menu to remove the checkmark.

You can resize the expandable node to make wiring even easier, but it also takes a large amount of space on theblock diagram. Complete the following steps to resize a node on the block diagram.

• Move the Positioning tool over the node. Resizing handles appear at the top and bottom of thenode.
• Move the cursor over a resizing handle to change the cursor to the resizing cursor.
• Use the resizing cursor to drag the border of the node down to display additional terminals.
• Release the mouse button.

To cancel a resizing operation, drag the node border past the block diagram window before you release themouse button.

shows the Basic Function Generator VI as a resized expandable node.

Terminals

Front panel objects appear as terminals on the block diagram. The terminalsrepresent the data type of the control or indicator. You can configure front panel controls or indicators to appear asicon or data type terminals on the block diagram. By default, front panel objects appear as icon terminals. Forexample, a knob icon terminal, shown at left, represents a knob on the front panel. The DBL at the bottom of theterminal represents a data type of double-precision, floating-point numeric. To display a terminal as a data typeon the block diagram, right-click the terminal and select View As Icon from the shortcut menu to remove the checkmark. A DBL data type terminal, shown above atleft, represents a double-precision, floating-point numeric control or indicator.

Terminals are entry and exit ports that exchange information between the front panel and block diagram. Terminals areanalogous to parameters and constants in text-based programming languages. Types of terminals include control orindicator terminals and node terminals. Control and indicator terminals belong to front panel controls andindicators. Data you enter into the front panel controls ( $a$ and $b$ in ) enter the block diagram through the control terminals. The data then enter the Add and Subtract functions. When the Add and Subtract functions complete their internal calculations, they produce new datavalues. The data flow to the indicator terminals, where they exit the block diagram, reenter the front panel, and appearin front panel indicators ( $a+b$ and $a-b$ in ). The terminals in belong to four front panel controls and indicators. The connector panes of the Add and Subtract functions, shown in , have three node terminals. To display the terminals of the function on the block diagram, right-clickthe function node and select Visible Items>>Terminals from the shortcut menu.