Communication Protocols
Copyright IXXAT Automation GmbH
107
IEM Manual, 1.5
5.3
EtherCAT
5.3.1 Device Description File
A template of a device description file for the IEM (IXXAT IEM *.xml) is includ-
ed in the software package. To establish bus communication, modification of
the file is not necessary. Data Objects have to be added if they are supposed
to be visible in offline mode of the configuration tool.
To modify the device description file to your own needs please refer to the
document “EtherCAT Slave Information Specification [ETC3]” provided by the
ETG.
5.3.2 Device addressing
EtherCAT uses a 16 bit device addressing. Automated logical addressing as
well as fixed station addressing (e.g. set by rotary switches) is supported. A
station address value unequal zero can be configured during startup. This ad-
dress is stored at the E2PROM and corresponding register values are actual-
ized.
5.3.3 E²PROM
The E2PROM required by EtherCAT is represented by a specific flash area at
the IEM. The start address of this area is depending on the size of the availa-
ble flash (e.g. 2 MB or 8 MB). The area starts with a code header used for in-
ternal checks, followed by the ESI content describing the device configuration.
The FW reads E2PROM contents during startup and updates the fix station
address if necessary. E2PROM content can be read and modified by engi-
neering tool without limitation, so be careful when writing the E2PROM.
5.3.4 Data access
5.3.4.1 Protocol specific addressing
Data used with EtherCAT are organized in objects defined by 16 bit index and
8 bit sub index. To address the object data that shall be read or written, index
and subindex of the addressed object have to be specified.
Objects can be variables, arrays and records. Variables have only one subin-
dex 0, arrays and records are structures with same or different elements.
The IEM supports CoE (CAN application layer over EtherCAT). This is availa-
ble as standard mechanism.