Glossary of POWERLINK terms
POWERLINK, like many other networking systems, has a set of unique terminology. Table below contains
a few of the technical terms used in this guide to describe the POWERLINK interface. They are listed in
alphabetical order.
Ageing
Ageing is a common mechanism to maintain (cache) tables.
Entries which are not used or refreshed are removed after a
specified time.
Application Process
The Application Process is the task on the Application Layer.
Async-only CN
An Async-only CN is operated in a way, that it is not accessed
cyclically in the isochronous slot by the MN. It is polled during
the asynchronous period by a StatusRequest message.
Asynchronous Data
Data in a POWERLINK network which is not time critical.
Within the POWERLINK cycle there is a specific period reserved
for Asynchronous Data which is shared by all nodes. Each
node connected to the network can send asynchronous data
by requesting it to the Managing Node. The Managing Node
keeps a list of all asynchronous data requests and will
subsequently grant the network access to one node after the
other. Refer also to page 65.
Asynchronous Period
The Asynchronous Period is the second part of the
POWERLINK cycle, starting with a Start of Asynchronous (SoA)
frame. Refer to page 65.
Asynchronous Scheduling
The MN’s asynchronous scheduler decides when a requested
asynchronous data transfer will happen.
Basic Ethernet Mode
Basic Ethernet Mode provides the Legacy Ethernet
communication. Refer also to page 69.
Bus
A bus is a communication medium connecting several nodes.
Data can be transferred via serial or parallel circuits, that is,
via electrical conductors or fiber optic.
CANopen
CANopen is a network technology optimized for the usage in
industrial control environments, in machine internal networks
and in embedded systems (any control unit deeply
"embedded" in a device with electronics). The lower-layer
implementation of CANopen is based upon CAN (Controller
Area Network).
Continuous
Continuous is a POWERLINK communication class where
isochronous communication takes place every cycle (the
opposite to multiplexed).
Controlled Node (CN)
Node in a POWERLINK network without the ability to manage
the SCNM mechanism. Refer to page 63.