Introduction; Protocol Architecture - Omron C200HW-PRM21 Operation Manuals

Introduction

1-1

Introduction

Multi-vendor
Standard
EN 50170
High speed
Process Automation
Higher level
Uniform bus access protocol
!
Caution
1-2

Protocol architecture

OSI
2
PROFIBUS is a vendor-independent, open fieldbus standard for a wide range
of applications in manufacturing, process and building automation. Vendor
independence and openness are guaranteed by the PROFIBUS standard
EN 50170. With PROFIBUS, devices of different manufacturers can
communicate without special interface adjustments.
The PROFIBUS family consists of three compatible versions:
PROFIBUS-DP
DP stands for Decentralised Periphery. It is optimised for high speed and low-
cost interfacing, especially designed for communication between automation
control systems and distributed I/O at the device level.
PROFIBUS-PA
PA stands for Process Automation. It permits sensors and actuators to be
connected on one common bus line even in intrinsically-safe areas. It permits
data communication and power supply over the bus using 2-wire technology
according the international standard IEC 1158-2.
PROFIBUS-FMS
FMS stands for Fieldbus Message Specification. This version is the general-
purpose solution for communication tasks at a higher level. Powerful services
open up a wide range of applications and provide great flexibility. It can also
be used for extensive and complex communications tasks.
PROFIBUS-DP and PROFIBUS-FMS use the same transmission technology
and a uniform bus access protocol. Thus, both versions can be operated
simultaneously on the same cable. However, FMS field devices cannot be
controlled by DP masters or vice versa.
It is not possible to exchange one of these family members by another family
member. This will cause faulty operation.
The rest of this section only describes PROFIBUS-DP.
The PROFIBUS protocol architecture is oriented on the OSI (Open System
Interconnection) reference model in accordance with the international
standard ISO 7498. Layer 1 (physical layer) of this model defines the physical
transmission characteristics. Layer 2 (data link layer) defines the bus access
protocol. Layer 7 (application layer) defines the application functions.
Section 1-1