from ethercat-1.5.0-patches-v2.tar.bz2
by Frank Heckenbach f.heckenbach@ at fh-soft.de
Ref: http://lists.etherlab.org/pipermail/etherlab-dev/2014/000404.html
with some additional edits.

Internal SDO requests are managed by master FSM and can conflict with
external requests managed by slave FSM. The internal SDO requests
includes SDO requests created by an application and external request are
typical created by EtherCAT Tool for SDO upload/download or a directory
fetch initiated with ethercat sdos command. The conflict will cause a
FPWR from an external request to be overwritten by a FPWR from an
internal SDO request (or oppersite) in the same "train" of datagrams.

The EoE MAC address is now derived from the NIC part of the first global
unique MAC address of the linked list of available network interfaces or
otherwise the MAC address used by the EtherCAT master. The EoE MAC address
will get the format 02:NIC:NIC:NIC:RP:RP where NIC comes from the unique MAC
address (if available) and RP is the ring position of the EoE slave.