Setup: Device EtherCAT

Notes on the EtherCAT device

• The CU2508 downlink port appears as the first regular EtherCAT slave. It can optionally represent the Distributed Clocks reference clock in this EtherCAT system. The port has no controllable I/O.
• All CU2508 downlink ports are synchronized with each other.
• A second CU2508 port can be used as a ring closure for EtherCAT cable redundancy. The primary EtherCAT connection must then be connected to an odd CU2508 port (X1, X3 etc.) and the secondary redundancy adapter to the following even CU2508 port (refer to the corresponding chapter Device EtherCAT with cable redundancy).
• The CU2508 sends EtherCAT frames in pass-through mode without time stamps.

Setting up an EtherCAT device

In EtherCAT operation the CU2508 downlink port used is not transparent, but appears as a Distributed Clocks-capable EtherCAT slave in the configuration. As a result it can appear as a reference clock. However, the EtherCAT slave is otherwise not parameterizable or addressable.

As applies to every EtherCAT device, the current ESI xml files should be present in the TwinCAT system for the CU2508 also. This applies both to the offline creation of the configuration and to scanning in online operation. The files (in particular “Beckhoff CUxxxx.xml”) can be procured from the download area on the Beckhoff web page. They are to be saved under "… \ TwinCAT\Io\EtherCAT\".

Updating the ESI XML files If the following information window should appear in online mode when scanning the devices on the CU2508: (see Fig. Information window "Online description") then an update for above mentioned file is necessary: Click on "No", close the System Manager window, install the current ESI xml files and create the configuration in a newly opened System Manager window.

Creation of the configuration The simple option to create the configuration by scanning the real hardware is only possible if an EtherCAT device is manually connected to a CU2508 port in the configuration.

Configuration settings under TwinCAT 2.11R2

Creating an EtherCAT device

An EtherCAT device can be added by right-clicking on I/O Device - > Append Device.

The desired downlink port of the CU2508 can now be selected.

The device "Device 2 (EtherCAT)" is now connected, according to the adapter reference, not to a physical Ethernet port of the controller, but to a logical adapter reference of the CU2508. This assignment can also be changed later. The freerun cycle time in the TwinCAT ConfigMode is shown here for the adapter.

Creation of the configuration Scanning of the EtherCAT configuration is also possible from this state onwards.

Creating a CU2508 box

The CU2508 downlink port appears as an EtherCAT slave and can be scanned or created manually.

If creating manually, the “CU2508 Ethernet port” CU2508-0000 must be selected. The check box "ExtendedInformation" displays the revision numbers, in this case -0000 (fig. Selection of “CU2508 Ethernet Port”).

If "CU2508" is entered in the Search mask, the overview is reduces to the sought device.

Fig. 7: Selection of “CU2508 Ethernet Port”

Further EtherCAT slaves can now be appended to the CU2508 Box.

Distributed Clocks settings

All CU2508 downlink ports are synchronized with each other and can appear as ReferenceClock in the respective EtherCAT strand. In the default setting, however, the CU2508 port is not marked as Distributed-Clocks-capable, hence under TwinCAT the next subsequent Distributed-Clocks-capable slave is selected as the ReferenceClock. In each case the CU2508 port is the 1^st slave in the respective strand.

If the CU2508 port is to be used as the ReferenceClock in a system, the setting "Use as potential ReferenceClock" must be changed; see fig. CU2508 slave - Distributed Clocks setting.

Synchronized EtherCAT systems If several EtherCAT systems are to be operated on CU2508 ports synchronized with the same time base, the flag "Use as potential Reference Clock" must be set in the appropriate "CU2508 box". External synchronization to another time base is then not possible.

The internal clock in the CU2508 works independently and is only managed by the CU2508 driver.

EoE settings (Ethernet over EtherCAT)

If devices with EoE support are used in a lower-level EtherCAT system, this affects the settings of the EoE switch in the CU2508 if this is configured for EoE transport. Refer to the Notes pages on TCP/IP traffic.

If such devices are present in the EtherCAT system,

• the Virtual Ethernet Switch must be enabled (“Enable”)
• “Connect to TCP/IP Stack” can be activated
• the numbers "Max Frames" and "Max MAC IDs" can be increased if throughput problems are determined

If several EtherCAT system EoE devices are used, this increases the settings of the CU2508 EoE switch.