Rockwell Automation 1770, D17706.5.16 Ref Mnl DF1 Protocol Command - Manual (Page 18)

Chapter
1
Publication 1770Ć6.5.16 - October 1996
Network Layers
Your network is made up of several layers, including:
Physical layer transmits bits between communication devices.
DataĆlink layer runs protocol to guard against errors, detects errors, and corrects
errors. Packages data and puts it onto the physical cable. Manages the flow of the
data bit stream into and out of each network node.
Network layer establishes connections for communication between network nodes.
Transport layer performs segmentation and reĆassembly of messages.
Provides recovery from transmission errors.
Session layer establishes and terminates network communications between
applications.
Presentation layer manages data formats for the applications.
Application layer serves as the window through which applications access
communication services, including file transfers, virtual terminal functions, and email.
Nodes send data through the layers.
In this chapter, we discuss the physical, data-link, and application
layers. (We refer to the data-link and application layers as the
software layers.) This chapter contains these sections:
Section Page
Physical Layer 1-2
Software Layers 1-7
Message Packet Structure 1-9