ABB FEPL-02 Ethernet POWERLINK, Руководство пользователя

Страница: 21 / 142

Overview of the Ethernet POWERLINK network and the FEPL-02 module 21
3
Overview of the Ethernet
POWERLINK network and the
FEPL-02 module
What this chapter contains
This chapter contains a short description of the Ethernet
POWERLINK network and the FEPL-02 Ethernet POWERLINK
adapter module.
Ethernet POWERLINK network
Ethernet POWERLINK is a communication profile for Real Time
Ethernet. It extends standard Ethernet IEEE802.3 with a
mechanism to transfer data deterministically. The mechanism is
called Slot Communication Network Management (SCNM). SCNM
is managed by a networked device designated as the Managing
Node (MN). All other nodes are Controlled Nodes (CN).
Unlike standard Ethernet, SCNM ensures that only one node is
accessing the network at a time. The schedule is divided into an
isochronous phase and an asynchronous phase. During the
isochronous phase, time-critical data is transfered, while the
asynchronous phase provides bandwidth for the transmission of
data that is not time-critical. The MN grants access to the physical
medium via dedicated poll request messages. As a result, only one
CN has access to the network at a time, and thus no collisions
occur.