Programming in the CFC editor

In the CFC editor, you can wire POUs to each other and create well-structured block diagrams.

The editor supports you in the following ways:

Programming with elements and connecting lines
Dragging instances and variables to the editing area
Auto-routing the connecting lines
Automatic linking
Fixing of connecting lines by control points
Collision detection
Input assistance for connection marks
Forcing and writing of values in online mode
Movement of selection using arrow keys
Reduced display of a POU without disconnected pins

Inserting elements and wiring with connecting lines

Drag a “Box” element and an “Output” element into the editor.
Click the output of the “Box” element.

The output is marked with a red box.
Drag a connecting line from the box output of the “Box” element to the box input of the “Output” element.

The cursor symbol changes when it reaches the box input.
Release the left mouse button.

The output pin of the box is wired to the input pin of the output.

You can also hold down the [Ctrl] key, select each pin, and then right-click “Connected Selected Pins”.

Calling of instances

Create a new project using the standard template and specify the name ‎First‎ for example.

The project ‎First.project‎ is created.

Extend the application with the function block ‎FB_DOIt‎ in the “ST” implementation language with inputs and outputs.

FUNCTION_BLOCK FB_DoIt
VAR_INPUT
	iAlfa : INT;
	iBravo: INT;
	sCharlie : STRING := 'Charlie';
	xItem : BOOL;
END_VAR
VAR_OUTPUT
		iResult : INT;
		sResult : STRING;
		xResult : BOOL;
END_VAR
VAR
END_VAR

iResult := iAlfa + iBravo;

IF xItem = TRUE THEN 
	xResult := TRUE;
END_IF

Select the application and click “Add Object POU” in the context menu. Select the “Continuous Function Chart (CFC)” implementation language and the type ‎Program‎. Specify the name ‎PrgFirst‎ for example.

Click “OK” to confirm the dialog.

The program ‎PrgFirst‎ is created and it opens in the editor. It is still empty.

Instantiate function blocks and declare variables.

PROGRAM PrgFirst
VAR
	iCounter: INT;

	fbDoIt_1 : FB_DoIt;
	fbDoIt_2 : FB_DoIt;
	 
	iOut : INT;
	sOut: STRING;
	xOut: BOOL;

END_VAR

Drag a “Box” element from the “ToolBox” view into the editor.
Click the ‎???‎ field and type in ‎ADD‎.

The box type is ‎ADD‎. The box acts as an adder.
Click line 3 in the declaration editor.

The declaration line of ‎iCounter‎ is selected.
Click in the selection and drag the selected variable into the implementation. Focus there on an input of the ‎ADD‎ box.

An input has been created, declared, and connected to the box.
Click again in the selection and drag the variable to the output of the ‎ADD‎ box.

An output has been created, declared, and connected to the box.
Drag an “Input” element from the “ToolBox” view to the implementation. Click its ‎???‎ field and type in ‎1‎.
Connect the ‎1‎ input to an input of the ‎ADD‎ box.

A network is programmed. At runtime, the network counts the bus cycles and stores the result in ‎iCounter‎.
Click line 5 in the declaration editor.

The line is selected.
Click in the selection and drag the selected instance into the implementation.

The instance appears as a POU in the editor. The type, name, and POU pins are displayed accordingly.

Drag the ‎fbDoIt_2‎ instance to the editor. Interconnect the instances to each other and to inputs and outputs.

Example:

_cds_img_cfc_first_network_add_doit1_doit2

A program in ST with the same functionality might look like this:

PROGRAM PrgFirstInSt
VAR	
	iCounter: INT;

	fbDoIt_1 : FB_DoIt;
	fbDoIt_2 : FB_DoIt;
	 
	iOut : INT;
	sOut: STRING;
	xOut: BOOL;

END_VAR
iCounter := iCounter + 1;
fbDoIt_1(iAlfa := 16, iBravo := 32, sCharlie := 'First', xItem := TRUE, iDelta := 2, iResult => fbDoIt_2.iAlfa, xResult => fbDoIt_2.xItem);
fbDoIt_2(iBravo := fbDoIt_1.iResult, sCharlie := 'Second', iDelta := 2, iResult => iOut , sResult=> sOut, xResult => xOut);

Creating connection marks

Requirement: A CFC POU has connected elements.

Select a connecting line between two elements.

The connecting line is displayed as selected. The ends of the connecting line are marked with red boxes ().
Click “CFC Connection Mark”.

The connection is separated into a “Connection Mark - Source” and a “Connection Mark - Sink”. The name of the mark is generated automatically.
Click in the source connection marks.

You can edit the name.
Specify a name ‎SimpleMark‎ for the source connection mark.

The source connection mark and sink connection mark have the same name.

Resolving collisions and fixing connecting lines by means of control points

The following example shows how to use the “Route All Connections” command with control points.

Position the “Input” and “Output” elements. Connect the elements.
Position two “Box” elements on the line.

The connecting line and the boxes are marked red because of the collision.
Click “CFC Routing Route All Connections”.

The collision is resolved.
Change the connecting lines gradually.

The connecting line has been changed manually and is now blocked for auto-routing. This is shown by a lock symbol at the end of the connection.
Select the connecting line and click “CFC Routing Create Control Point”.

A control point is created on the connecting line. The connecting line is fixed to the control point.

You can also drag a control point from the “ToolBox” view to a line.
Change the connecting line as seen in the following example.

Use the control point for changing the connecting line according to your needs. You can set any number of control points.
In the context menu, click “CFC Routing Remove Control Point” to remove the control point.
Unlock the connection by clicking “Unlock Connection” or by clicking the lock symbol.
Select the connecting line and click “Route All Connections”.

The connecting line is routed automatically as seen in Step 3.

NOTICE

Connections in a group are not auto-routed.

Reducing the display of a POU

Requirement: A CFC POU is open. In the editor, its POUs with all declared pins are displayed.

Select a POU whose pins are partially disconnected.

Example: ‎fb_DoIt_1‎

The POU needs space for all of the pins.
Click “CFC Pins Remove Unused Pins”.

Now the POU needs less space and is displayed only with the functionally relevant pins.