Installation guide

Network Infrastructure for EtherNet/IP™
Industrial Ethernet… Not Just Another Fieldbus
1-3
receiving devices can consume this data simultaneously. Implementation of this model in CIP is
supported by the Internet Protocol (IP) multicast service which, in its turn, is supported by the Ethernet
multicast service. The primary benefit of a producer-consumer network is its more efficient use of
bandwidth. When a message is produced on the network, it is identified not by its destination address, but
by its connection ID. Multiple nodes may then consume the data to which the connection ID refers. As a
result, if a node wants to receive data, it only needs to ask for it once in order to consume the data each
time it is produced. And, if a second (third, fourth, etc.) node wants the same data, all it needs to know is
the connection ID to receive the same data simultaneously with all other nodes.
Conversely, using the
source-destination model, nodes receive only the packets that contain their
destination node number. If more than one node needs the same data, it must be transmitted multiple
times, which is inherently inefficient. This can also cause synchronization problems, as nodes that require
the same data obtain it at slightly different times.
1.2.1 Industrial Ethernet and Traditional Fieldbuses
Since the mid-1990s, the use of fieldbuses, such as DeviceNet™, has grown significantly. At the same
time, advances in Ethernet switching technology and significant cost reductions fueled by the expanded
use of PCs and the Internet now allow industrial Ethernet to be used in more manufacturing applications.
Depending on the application, it may be desirable to combine Ethernet networks with fieldbus-type
networks. CIP Networks, such as EtherNet/IP and DeviceNet, support seamless bridging and routing
between multiple CIP Networks.
Implementing an industrial Ethernet system is different than implementing a device-level network, such
as DeviceNet. Whether installing a homogeneous EtherNet/IP network architecture or a heterogeneous
CIP Network architecture, users must be aware of the basic differences between Ethernet networks, such
as EtherNet/IP, and typical fieldbuses, such as DeviceNet, as highlighted in Table 1-1.
Table 1-1 Comparison of Device-level Networks and Industrial Ethernet Implementations
Control System Issue
Typical Device-level
Network Capability
Industrial Ethernet
Capability
Industrial Ethernet
Differences
Device capacity and
wiring flexibility
Trunk-and-drop,
typically 10s of devices
Limited total network
distance
Star configuration with
potential for 100s or
1000s of devices
Virtually unlimited total
network distance
Infrastructure devices
required
Network management
tools may be needed
Data rate vs. distance
100s kbps, up to 500
meters (1600 ft) for
copper cable runs,
trading lower speed for
longer distance
10 Mbps to 100 Mbps,
up to 100 meters (328 ft)
for copper runs and up
to 2000 meters (6561 ft)
for fiber
Cable types and noise
immunity
Greater need for a mix
of fiber and copper
within a system
Protocols
Single protocol Coexistence of multiple
protocols
Coexistence of multiple
protocols