EtherNet/IP interface
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AMS 358
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Leuze electronic
9
EtherNet/IP interface
9.1
EtherNet/IP – general info
EtherNet/IP is an industrial communication network based on EtherNet and builds upon the
TCP/IP and UDP/IP protocols.
EtherNet/IP makes use of the (
CIP
)
C
ommon
I
ndustrial
P
rotocol as an application layer for
the user. CIP distinguishes between real-time communication by means of "implicit
messages" and custom, acyclic services, which are referred to as "explicit messages".
Explicit messages
Explicit messages are sent on the basis of TCP/IP. The receiver interprets the message as
an instruction, executes it, and generates a corresponding response. Explicit messages are
used, e.g., for device configuration, programming and for diagnostics and for communi-
cating non-time-critical data; they do not have a real-time characteristic.
Explicit messages are always sent using point-to-point communication.
All EDS objects of the AMS 358
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described in the following can be called up via explicit
services (e.g., get attribute single, set attribute single, etc.).
Implicit messages
Implicit messages are used to send real-time I/O data. For this purpose, EtherNet/IP does
not use TCP, but rather UDP (User Datagram Protocol) via IP (Internet Protocol). This
protocol is much more compact and supports multicast as well as unicast messages.
Implicit message telegrams are cyclically sent in short intervals with current data and I/O
signals (cycle can be configured via the control). The telegram overhead is minimal here. As
a result, these messages can be processed very quickly and according to priority.
Within the AMS 358
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, the input and output assemblies for transferring measurement values
by means of UDP are transferred and are thereby deterministically available in a cycle config-
ured via the control.
For implicit messages, EtherNet/IP uses the producer/consumer communication model for
data exchange. A producer is a device that sends data; a consumer is a device that receives
data. Multiple consumers can thereby simultaneously receive and evaluate a producer
message in the multicast operating mode.
In general, it must be observed that, when using multicast, the messages are sent to all
participants by way of a broadcast. This causes the data traffic on the network to increase
considerably. Should the data only be transmitted between the AMS and the PLC, we
recommend configuring the unicast operating mode on the control for this participant.
