Configuring a Network Variable Exchange

Select the application and insert a Network Variable List (Sender) object. In the Add Network Variable List (Sender) dialog, configure the following settings: network type: UDP (example: "NVL_Sender").

Double-click the NVL object to open the respective editor and type the declarations of the network variables. Example:

VAR_GLOBAL

iglobvar:INT;

bglobvar:BOOL;

strglobvar:STRING;

END_VAR

Right-click the NVL object in the device tree to open the Properties. In the Properties dialog, open the Network Variables tab. This shows the following settings: Network type: UDP; List identifier: 1; Pack variables; Cyclic transmission: every 50 ms.

Note: You can also convert an existing GVL into a network variable list by configuring its network variable properties.

In the Properties dialog of the NVL_Sender, click the Link to File tab. Define a file name <export>.gvl and a location in the file system for the export file of the GVL. Select the Export before compile option.

Click Build → Build to compile the application.

Select the application of the receiver in the device tree and click Add Object → Network Variable List (Receiver).

In the dialog, select the previously created NVL of the sender device and specify a name (example: "NVL_Receiver"). CODESYS automatically populates this receiver list with the variable declarations from the sender list.

Note: As an alternative, you can select the Import from file option and load the export file that was generated previously from the sender list.

Below the application in the sender device, create a program that increments a network variable.

Example: iglobvar:=iglobvar+1;

Configure the application task so that this program calls it.

Below the application in the receiver device, create a program that writes the value of this network variable to a local variable.

Example: ilocalvar:=iglobvar;

Configure the application task so that this program calls it.

Download both applications to the controllers and start them. (Set the application as active, login, download, and start)

In the online views of the editors of both programs, check whether the values of iglobvar match in the receiver and the sender.

Open the Properties dialog of the GVL in the V2.3 project (sender).

Insert another PLC into the project as a dummy with an application and a task. Then create the V2.3 GVL below it as follows:

Insert a Network Variable List (Sender) object named "dummy23" below the dummy application.

Right-click dummy23 to open the Properties dialog. Click the Network Properties tab. Type the same network properties as the GVL in the V2.3 project.

Fill dummy23 with the same variable declarations as in the V2.3 GVL.

Define a location for an export file "dummy23.gvl" on the Link To File tab of the Properties for dummy23.

Set the application of the dummy controller to active and click Build → Generate Code (F11).

Set the application of the physical PLC as active and right-click to open the Add Object dialog.

Select Network Variable List (Receiver) and specify a name (example: "NVL_from_23").

Select the Import from file option and select dummy23.gvl, which was generated previously.

Check NVL_from_23, which has just been created. You have to get the same variable declarations as those in the sender GVL in the V2.3 project.