BECKHOFF EtherCAT Technology Section I - Manual (Page 92)

SII EEPROM
I-72 Slave Controller – Technology
11 SII EEPROM
EtherCAT slave controllers use a mandatory NVRAM (typically a serial EEPROM with I²C interface) to
store EtherCAT Slave Information (ESI). EEPROM sizes from 1 Kbit up to 4 Mbit are supported,
depending on the ESC.
The EtherCAT IP Core supports omitting the serial I²C EEPROM if a µController with read/write
access to an NVRAM (e.g.,
the one which contains the µController’s program and data, or the FPGA
configuration EPPROM) is used to emulate the EEPROM transactions. Since the logical interface is
the same in this case, the EEPROM emulation is treated to be equivalent to the typical I²C EEPROM
solution throughout this chapter. Refer to chapter 11.2.4 for more details about EEPROM emulation.
The EEPROM structure is shown in Figure 36. The ESI uses word addressing.
EtherCAT Slave Controller Configuration Area
VendorId ProductCode RevisionNo SerialNo
Additional Information (Subdivided in Categories)
…
0
8
16
Word
64
Hardware Delays Bootstrap Mailbox Config
24
Reserved
Mailbox Sync Man Config
Category FMMU
Category Strings
Category Generals
Category SyncManager
Category Tx- / RxPDO for each PDO
Figure 36: SII EEPROM Layout
At least the information stored in the address range from word 0 to 63 (0x00 to 0x3F) is mandatory, as
well as the general category (
→ absolute minimum SII EEPROM size is 2Kbit, complex devices with
many categories should be equipped with 32 Kbit EEPROMs or larger). The ESC Configuration area
is used by the ESC for configuration. All other parts are used by the master or the local application.
For a more detailed description of the ESI and other mandatory parts refer to the ETG.2000 EtherCAT
Slave Information (ESI) Specification, available from the download section of the EtherCAT
Technology Group website (
http://www.ethercat.org ).