Profibus
Profibus is a fieldbus system with FMS and DP, which
can be used for linking automation units, such as sen-
sors and actuators, to the controls by means of a two-
conductor cable.
Profibus FMS is used if major communication tasks
are to be solved at cell and system level by means of
large volumes of data.
Profibus DP is an extremely fast communication pro-
tocol, made specially for communication between the
automation system and various units.
LON - Local Operating Network
LonWorks is an intelligent fieldbus system which im-
proves the possibility of decentralising control, as com-
munication is enabled between individual units in the
same system (Peer-to-Peer).
This means that there is no need for a big main station
for handling all the signals of the system (Master-
Slave). Signals are sent direct to the unit that needs
them via a common network medium. This makes
communication much more flexible and the central
building state control and monitoring system can be
changed into a dedicated building state monitoring
system whose task is to ensure that everything is run-
ning as planned. If the potential of LonWorks is fully
utilised, sensors will also be connected to the bus,
which means that a sensor signal can quickly be
moved to another controller. If room dividers are mo-
bile, this is a particularly useful feature.
DeviceNet
DeviceNet is a digital, multi-drop network, based on
the CAN protocol, that connects and serves as a com-
munication network between industrial controllers and
I/O devices.
Each device and/or controller is a node on the network.
DeviceNet is a producer-consumer network that sup-
ports multiple communication hierarchies and mes-
sage prioritization.
DeviceNet systems can be configured to operate in a
master-slave or a distributed control architecture using
peer-to-peer communication. This system offers a sin-
gle point of connection for configuration and control by
supporting both I/O and explicit messaging.
DeviceNet also has the feature of having power on the
network. This allows devices with limited power re-
quirements to be powered directly from the network via
the 5-conductor cable.
Modbus RTU
MODBUS RTU (Remote Terminal Unit) Protocol is a
messaging structure developed by Modicon in 1979,
used to establish master-slave/client-server commu-
nication between intelligent devices.
MODBUS is used to monitor and program devices; to
communicate intelligent devices with sensors and in-
struments; to monitor field devices using PCs and
HMIs.
MODBUS is often applied in Gas and Oil applications,
but also in building, infrastructure, transportation and
energy, applications are making use of its benefits.
VLT
®
6000 HVAC Series
MG.61.B5.02 - VLT
®
is a registered Danfoss trademark 33
Introduction to HVAC
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