Allen-Bradley PLC-5 MAP/OSI, User Manual, Page: 9 / 135

Chapter
1
1-1
Overview of the MAP Communication
Environment
This chapter introduces you to MAP communication and shows how it
relates to your OSI coprocessor. This chapter covers:
Open Systems Interconnect (OSI)
Manufacturing Automation Protocol (MAP)
Manufacturing Message Specification (MMS)
the MMS Modeling Concept
MAP communications and your OSI coprocessor
The following sections contain general overviews of these subjects and are
not meant to provide in–depth information. If you are already familiar
with these topics, you may want to proceed to Chapter 2.
The Open Systems Interconnect (OSI) is a standard that provides the
framework for defining the process of communication between nodes (i.e.,
computers, terminals, PLC controllers). There are many activities that
need to be accomplished when two nodes communicate with each other
over the network. The OSI standard defines these activities in its
seven–layer reference model (figure 1.1).
Figure 1.1
The OSI Seven-layer Reference Model
Application
7
Presentation
6
Session
5
Transport
4
Network
3
Data Link
2
Physical
1
I - 12406
The seven layers define the:
Chapter Objectives
Open Systems Interconnect
(OSI)
AB Parts