ATI
MetriNet Ethernet/IP Communications Manual
4
O&M Manual
Rev-A (6/19)
1.3
Ethernet/IP Transmission Details
It should be understood that Ethernet/IP is simply an application layer protocol that
is transferred over an Ethernet hardware link. The word "Ethernet" simply refers
to the common physical cable, perhaps running to an office PC.
In the OSI model, “Ethernet” is the lower part of the model, the physical transfer
method or the hardware. It says nothing about the way information is transferred,
which is specified near the top of the OSI model. In the common office network,
many different standard communication protocols are operating during normal
office use, like IP, TCP, etc. None of these are designed to handle the CIP
industrial format, so that interface must be handled by a specific program that
recognizes the format. Because of this, an Ethernet/IP device cannot be directly
connected to your office network for transferring information.
The data for the protocol is constructed into a specific structure inside a standard
TCP/IP Packet. A user application program simply decodes the structure inside
the received TCP or UDP packet. The data structure consists of a grouping of
data values called Attributes inside other sets of containment data called Objects.
There are Ethernet/IP required Objects and application Objects. Required objects
are typically - Identity, TCP, and Router. Application objects consist of some
defined data types, like a Motor Object, and some user specific data types.
1.4
Cable Connection
The cable used for Ethernet/IP communication should meet the CAT5 standard
defined by the Electronic Industries Association and Telecommunications Industry
Association. It is readily available in lengths up to 100 ft. (30 m) with plugs on each
end.
To install an Ethernet cable in the MetriNet, pass the unterminated cable through
the cable gland nearest the location of the RJ45 connector on the Ethernet/IP
option board. Provide a slight service loop amount of slack so that the terminated
cable will not be pulling directly on the RJ45 connector once installed. Termination
of Cat5/5e/6 cables is very easy and can be completed quickly with the commonly
available RJ45 crimp tool.
Note that there a reconnection LEDs present on the face of the RJ45 connector,
which can be used to verify activity on the interface. Rather than detail their
specific use, it is sufficient to just very flashing on these LEDS when the unit is
powered up or actively communicating with the network client.
