EtherCAT Protocol

The Ethernet for Control Automation (EtherCAT) is an open, high-performance Ethernet network protocol for real-time distributed control. You can use an EtherCAT network instead of an Ethernet network because the EtherCAT protocol provides:

• Deterministic and fast cycle times

• Inexpensive hardware cost

EtherCAT networks consist of one master node and several slave nodes. The xPC Target EtherCAT sublibrary supports only the master node of an EtherCAT network. In other words, you cannot emulate slave nodes using these blocks. However, you can prototype multiple EtherCAT controllers, with multiple Ethernet cards, using these blocks.

This topic assumes that you:

• Are familiar with Ethernet and EtherCAT networks

• Are familiar with CAN networks

• Are familiar with CANopen networks

• Have access to and know how to use the Beckhoff^® ET9000 EtherCAT configurator software

Before You Start

1. Provide a dedicated Ethernet card on your target computer. A dedicated Ethernet card is to be used only for model-based EtherCAT communications and not for communication between the host computer and target computer. This requirement means that your target computer must have at least two Ethernet cards, one for host computer to target computer communications, and one for model-based EtherCAT communication.

   Tip   For a list of supported chip sets, see EtherCAT Chip Sets.

2. Download or purchase the Beckhoff ET9000 EtherCAT configurator software, available at:

   http://www.beckhoff.com/english.asp?ethercat/et9000_et9200_et9300.htm

3. Design and configure an EtherCAT network.

4. Create an EtherCAT configuration XML file for this network. The xPC Target EtherCAT blocks require this configuration XML file.

Basic Workflow

This topic describes a basic workflow for using the xPC Target EtherCAT sublibrary. It assumes that you:

• Have an EtherCAT network

• Have access to the EtherCAT configurator software

• Know how to use the EtherCAT configurator software to create a configuration XML file

See Before You Start for more information.

1. Connect to the EtherCAT network.

2. Use the Beckhoff ET9000 configurator to configure the EtherCAT network.

   This step produces a network configuration file, contained in an XML file.

   Note:   The xPC Target documentation does not describe how to use Beckhoff ET9000 configurator software.

3. From the Beckhoff ET9000 configurator, export the XML configuration file.

4. In the xPC Target model for the EtherCAT master, add an xPC Target EtherCAT Init block.

   Tip   The xPC Target EtherCAT blocks are not available in the standard xPC Target library. To access these blocks, type xpcethercatlib in the MATLAB Command Window.

5. Double-click the Init block and enter the configuration file name from step 3 in the EtherCAT configuration file parameter. Use single quotes around the configuration file name.

    

6. Configure the rest of the block.

7. Add and configure other EtherCAT blocks, such as the EtherCAT Rx Var and EtherCAT Tx Var blocks. At the very least, each model must contain the EtherCAT Init, EtherCAT Rx Frames, and EtherCAT Update blocks. Add an EtherCAT Rx Var or EtherCAT Tx Var block for every EtherCAT device variable that is linked to a variable in an ET9000 task.

   When you add EtherCAT blocks to the model, the blocks automatically obtain the list of variables from the XML configuration file specified in their associated EtherCAT Init block. The parameter dialog boxes of these blocks are updated with the configuration information.

8. Repeat steps 1 to 6 for each EtherCAT network that you want. Use a different Ethernet card interface for each EtherCAT network.

Execution Priority

The EtherCAT blocks have the following execution priority, from first to last:

1. EtherCAT Init

2. EtherCAT Rx Frames

3. EtherCAT Rx Var, EtherCAT Tx Var

4. EtherCAT Update

5. EtherCAT COE Read, EtherCAT COE Write, EtherCAT Get State, EtherCAT Set State

xPC Target Applications of the Beckhoff ET9000 EtherCAT Configurator

This topic lists the configurator components that have corresponding xPC Target elements. It does not describe how to use the configurator. See the Beckhoff ET9000 EtherCAT Configurator for documentation on how to use the tool.

• The EtherCAT configuration file that you specify in the EtherCAT Init block describes the network, including the device variables of the network. When you specify a device variable from this network, the block variable information corresponds to signal information on the block mask and block parameter dialog box.

• If your model contains the EtherCAT COE Read and EtherCAT COE Write blocks, include in the configuration file at least one cyclic input/output task linked to one of the slave device input/output channels.

• Do not name the configuration file with the name modelname.xml.

• Create at least one task for data transfers.

• To perform data transfers at multiple rates, create multiple tasks in the configurator.

  The task rate that you use in the configurator must match the greatest common divisor of the rates in the Simulink model. All tasks run at this rate. The greatest common divisor must be a multiple of the fixed Sample Time defined in the block parameter dialog box, or the fixed Sample Time must be auto.

• You can create more than one task at the same rate.

EtherCAT Chip Sets

The xPC Target EtherCAT communication blocks support the following Intel (Vendor ID 0x8086) chips:

EtherCAT Data Types

The xPC Target EtherCAT blocks support the following EtherCAT data types:

EtherCAT Error Values

The xPC Target EtherCAT blocks return the following EtherCAT error values: