Rockwell Automation 1755-OF8 GuardPLC Controller Systems - Manual (Page 200)

200 Publication 1753-UM001C-EN-P - March 2010
Chapter 18 Introduction to EtherNet/IP Communication
The GuardPLC controller can be used as a Class 1 adapter, a Class 3
adapter, or as an unconnected adapter to communicate to Logix
controllers, PLC-5 or SLC 5/05 controllers, or PanelView Standard
terminals. See
Chapter 19 for information on using the GuardPLC
controller as an adapter.
Class 1 Connections
GuardPLC assemblies may have various sizes and have signals of
different types associated with them. An EtherNet/IP scanner can
establish Class 1 connections to the GuardPLC controller to read from
the input assemblies and write to the output assemblies. When
establishing a Class 1 connection, the data is addressed by using the
unique instance number of the assembly object. This is similar to
establishing a Class 1 connection to an I/O module but different than
establishing a Class 1 connection to Logix controllers where data is
addressed by a name.
Class 3 Connections
An EtherNet/IP scanner may be used to establish Class 3 connections
to the GuardPLC controller. The Class 3 connection can be used to
send explicit requests to any of the implemented objects, including
Identity, Assembly, PCCC, Connection Configuration, Port, TCP/IP and
Ethernet Link. Connected explicit requests may be used to read
assembly data from an input adapter assembly and write data to the
output assembly.
Unconnected Adapter
Using the GuardPLC controller as an unconnected adapter is similar to
using it as a Class 3 adapter. In both cases, an explicit message is sent
from the client to the GuardPLC controller, addressing one of the
built-in objects, including Identity, Assembly, PCCC, Connection
Configuration, Port, TCP/IP and Ethernet Link. In the case of an
unconnected adapter, the message is not sent over a connection, but
is sent as a single, independent request.