Network Variable List (Receiver)

Overview

A network variable list (receiver) is added to the Applications tree. It defines variables, which are specified as network variables in another device within the network.

NOTE: The maximum size of a network variable is 255 bytes. The number of network variables is not limited.

Thus you can add a network variable list (receiver) object to an application if a network variable list (sender) with special network properties (network variable list) is available in one of the other network devices. This is independent of whether defined in the same project or in different projects. If several of appropriate network variable lists (sender) are found within the present project for the present network, select the desired network variable list (sender) from a selection list Sender when adding a network variable list (receiver) via the dialog box Add Object > Network Variable List (Receiver). Network variable lists (sender) from other projects must be imported as described in this chapter.

Therefore, each network variable list (receiver) corresponds exactly to one network variable list (sender) in another device.

Dialog box Add Network Variable List (Receiver)

Description of the Elements

When adding the network variable list (receiver), besides a Name, also define a Task, responsible for the handling of the network variables.

Alternatively to directly choosing a network variable list (sender) from another device, you can specify a network variable list (sender) export file *.GVL with the option Import from file. This network variable list (sender) file has been generated previously from the network variable list (sender) via View > Properties > Link To File dialog box. In any case this is necessary if the desired network variable list (sender) is defined within another project. For this purpose, select the option Import from file in the Sender selection list and enter the file path in the Import from file text field (or click the ... button to open the dialog for browsing in the file system).

You can modify the settings at a later time via the View > Properties > Network Settings dialog box.

A network variable list (receiver) is displayed by the NVL editor, but it cannot be modified. It displays the content of the corresponding network variable list (sender). If you modify the basic network variable list (sender), the network variable list (receiver) is updated accordingly.

A comment is added automatically at top of the declaration part of a network variable list (receiver), providing information on the sender (device path), the network variable list (sender) name, and the protocol type.

Network Variable List Example

Network variable list

NOTE: Only arrays whose bounds are defined by a literal or a constant are transferred to the remote application. Constant expressions in this case are not allowed for bounds definition. Example: arrVar : ARRAY[0..g_iArraySize-1] OF INT ; is not transferred arrVar : ARRAY[0..10] OF INT ; is transferred

For further information, refer to the Network Communication chapter.

Example of a Simple Network Variable Exchange

In the following example, a simple network variable exchange is established. In the sender controller, a network variable list (sender) is created. In the receiver controller, the corresponding network variable list (receiver) is created.

Perform the following preparations in a default project, where a sender controller Dev_Sender and a receiver controller Dev_Receiver are available in the Devices tree:

Create a POU (program) prog_sender below the Application node of Dev_Sender.
Under the Task Configuration node of this application, add the task Task_S that calls prog_sender.
Create a POU (program) prog_rec below the Application node of Dev_Receiver.
Under the Task Configuration node of this application, add the task Task_R that calls prog_rec.

NOTE: The 2 controllers must be configured in the same subnet of the Ethernet network.

Defining the Network Variable List (Sender)

Step 1: Define a global variable list in the sender controller:

Step	Action	Comment
1	In the Applications tree, select the Application node of the controller Dev_Sender and click the green plus button. Execute the command Add other objects > Network Variable List (Sender).	The Properties dialog box of the network variable list (sender) is displayed.
2	Enter the Name `GVL_Sender` and click Add to create a new global variable list.	The GVL_Sender node appears below the Application node in the Applications tree and the editor opens on the middle of the EcoStruxure Machine Expert screen.
3	In the editor, enter the following variable definitions: `VAR_GLOBAL iglobvar:INT; bglobvar:BOOL; strglobvar:STRING; END_VAR`	–

Step

Action

Comment

In the Applications tree, select the Application node of the controller Dev_Sender and click the green plus button. Execute the command Add other objects > Network Variable List (Sender).

The Properties dialog box of the network variable list (sender) is displayed.

Enter the Name GVL_Sender and click Add to create a new global variable list.

The GVL_Sender node appears below the Application node in the Applications tree and the editor opens on the middle of the EcoStruxure Machine Expert screen.

In the editor, enter the following variable definitions:

VAR_GLOBAL
iglobvar:INT;
bglobvar:BOOL;
strglobvar:STRING;
END_VAR

–

Step 2: Define the network properties of the network variable list (sender):

Step	Action	Comment
1	In the Applications tree, select the GVL_Sender node, click the green plus button, and execute the command Properties...	The Properties - GVL_Sender dialog box is displayed.
2	Open the Network properties tab and configure the parameters as indicated in the graphic:	–
3	Click OK.	The dialog box is closed and the network variable list (sender) network properties are set.

Defining the Network Variable List (Receiver)

Step 1: Define a global network variable list in the receiver controller:

Step	Action	Comment
1	In the Applications tree, select the Application node of the controller Dev_Receiver, click the green plus button, and execute the command Global Network Variable List....	The Add Global Network Variable List dialog box is displayed.
2	Configure the parameters as indicated in the graphic.	This global network variable list is the counterpart of the network variable list (sender) defined for the sender controller.
3	Click Open.	The dialog box is closed and the GNVL_Receiver appears below the Application node of the Dev_Receiver controller: This network variable list (receiver) automatically contains the same variable declarations as the GVL_Sender.

Step 2: View and / or modify the network settings of the network variable list (receiver):

Step	Action	Comment
1	In the Devices tree, right-click the GNVL_Receiver node and select the command Properties....	The Properties - GNVL_Receiver dialog box is displayed.
2	Open the Network settings tab.	–

Step 3: Test the network variable exchange in online mode:

Step	Action	Comment
1	Under the Application node of the controller Dev_Sender, double-click the POU prog_sender.	The editor for prog_sender opens on the right-hand side.
2	Enter the following code for the variable `iglobvar`:	–
3	Under the Application node of the controller Dev_Receiver, double-click the POU prog_rec.	The editor for prog_rec opens on the right-hand side.
4	Enter the following code for the variable `ivar_local`:	–
5	Log on with sender and receiver applications within the same network and start the applications.	The variable `ivar_local` in the receiver gets the values of `iglobvar` as currently displayed in the sender.