Beckhoff EL7201-0010, Documentation, Page: 48 / 208

Commissioning
6.1.2 Notes regarding ESI device description
Installation of the latest ESI device description
The TwinCAT EtherCAT master/System Manager needs the device description files for the devices to be
used in order to generate the configuration in online or offline mode. The device descriptions are contained
in the so-called ESI files (EtherCAT Slave Information) in XML format. These files can be requested from the
respective manufacturer and are made available for download. An *.xml file may contain several device
descriptions.
The ESI files for Beckhoff EtherCAT devices are available on the Beckhoff website .
The ESI files should be stored in the TwinCAT installation directory (default TwinCAT2: C:\TwinCAT\IO
\EtherCAT). The files are read (once) when a new System Manager window is opened, if they have changed
since the last time the System Manager window was opened.
A TwinCAT installation includes the set of Beckhoff ESI files that was current at the time when the TwinCAT
build was created.
For TwinCAT 2.11/TwinCAT 3 and higher, the ESI directory can be updated from the System Manager, if the
programming PC is connected to the Internet (Option -> “Update EtherCAT Device Descriptions”)
Fig. 43: For TwinCAT 2.11 and higher, the System Manager can search for current Beckhoff ESI files auto-
matically, if an online connection is available
Note
ESI
The *.xml files are associated with *.xsd files, which describe the structure of the ESI XML
files. To update the ESI device descriptions, both file types should therefore be updated.
Device differentiation
EtherCAT devices/slaves are distinguished by 4 properties, which determine the full device identifier. The
EL2521-0025-1018 ID consists of
• family key “EL”
• name “2521”
• type “0025”
• and revision “1018”
Fig. 44: Identifier structure
The order identifier consisting of name + type (here: EL2521-0010) describes the device function. The
revision indicates the technical progress and is managed by Beckhoff. In principle, a device with a higher
revision can replace a device with a lower revision, unless specified otherwise, e.g. in the documentation.
Each revision has its own ESI description. See
further notes [
}
8] .
Online description
If the EtherCAT configuration is created online through scanning of real devices (see section Online setup)
and no ESI descriptions are available for a slave (specified by name and revision) that was found, the
System Manager asks whether the description stored in the device should be used. In any case, the System
Manager needs this information for setting up the cyclic and acyclic communication with the slave correctly.
EL72x1-0010 48 Version: 2.0