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(HMI) - and not from the master (typically a PLC) that
controls the cyclic communication. Standard Profibus
does not support networks with several masters so
set-up and diagnostics information must be contained
in the standard telegram handled by the master,
making for very long and time-consuming telegrams
with room for information only sporadically used.
Profibus DP V1 now combines the two sets of
requirements from above in a single fieldbus system,
allowing a second master to use the entire network
in a specified time slot in each cycle. Profibus DP
V1 thus operates with two classes of masters.
Masterclass 1 (typically a PLC) performs the cyclic
communication. Masterclass 2, typically an interface
device (HMI or PC), transfers non-time critical
information through non-cyclic communication.
Masterclass 2 masters can be connected anywhere
on the Profibus net and the communication channel
can be opened and closed anytime without disturbing
the cyclic communication. You can have non-cyclic
communication even without cyclic communication to
for instance transfer complete programs or set-ups.
Profibus DP V1 is fully compatible with prior versions of
Profibus DP V0. Profibus DP V0 and Profibus DP V1
nodes can be combined in the same network, although
the master must support Masterclass 2 communication.
User benefits:
•
Connection to the motor controls is possible
from every part of the network
•
Existing network can be used for commissioning,
set-up and diagnostic without disturbing of
the cyclic communication
•
Both DP V1 and DP V0-nodes can be connected
in the same network
•
No need for extensive telegrams in the PLC
or IPC. A second master who supports DP
V1 can handle set-up tasks
NOTE
DP V1 is only possible for Master
communication-cards which support
Masterclass 2 specification.
DeviceNet
DeviceNet is a communications link that connects
industrial devices to a network. It is based on
34
Decentral Solutions
the broadcast-oriented, communications protocol
CAN (Controller Area Network).
The CAN protocol was originally developed for the
European automotive market to be used in exchange
for expensive wire harnesses in automobiles. As
a result, the CAN protocol offers fast response
and high reliability for demanding applications
like ABS brakes and air bags.
Danfoss concept offers the cost optimal
DeviceNet solution
•
Cyclic I/O communication
•
Acyclic communication - "explicit messaging"
•
Unconnected Messages Manager (UCMM)
messages are supported
•
Integrated solution
•
Electronic Data sheet (EDS)-files secures
easy configuring
•
Provides fieldbus voltage supply
•
Fulfilment of DeviceNet AC/DC motor profile
•
Protocol defined in accordance with the Open
DeviceNet Vendor Association (ODVA)
AS-interface
AS-interface (AS-i) is a cost-efficient alternative
to conventional cabling at the lowest level of the
automation hierarchy. The network can link into a
higher-level fieldbus like Profibus for low-cost remote
I/O. Known by its yellow cable; AS-I has grown an
"open" technology supported by more than 100
vendors worldwide. Enhancements through time have
broadened its field of applications and AS-interface is
today proven in hundreds of thousands of products
and applications spanning the automation spectrum.
InterBus
InterBus is an open, non-proprietary standard.
It complies with the EN 50254 standard. Using
decentralized motor controls with integrated
fieldbus communication allows you to connect
to an InterBus network.
•
Easy connection
•
Compliance with the international standard
EN 50254
•
I/O based transmission principle, high
protocol efficiency
•
Unified planning tool (e.g. CMD software)
MG.90.F2.22 - VLT is a registered Danfoss trademark
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