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CONTENTS INTRODUCTION OSI MODELS PHYSICAL LAYER EXAMPLE ADVANTAGE, DISADVANTAGE APPLICATION PROFIBUS (Process Field Bus) was first promoted in 1989 by BMBF (German department of education and research)
Department of Control and Automation INDUSTRIAL NETWORK PROFIBUS th Nov 13 , 2015 CONTENTS INTRODUCTION OSI MODELS PHYSICAL LAYER EXAMPLE ADVANTAGE, DISADVANTAGE APPLICATION INTRODUCTION PROFIBUS (Process Field Bus) was first promoted BMBF (German department of education and research) in 1989 by INTRODUCTION PROFIBUS is a widely accepted international networking standard IEC 61158 in 2000 INTRODUCTION PROFIBUS consists of Communication Profiles: FMS (Fieldbus Message Specification), DP (Distributed Peripheral), PA (Process Automation) OSI MODELS PHYSICAL LAYER With electrical transmission RS485, Bit rates from 9.6 kbit/s to 12 Mbit/s The cable length is limited from 100 to 1200m, primarily used with PROFIBUS DP With optical transmission via fiber optics, star-, bus- and ringtopologies are used The distance can be up to 15 km PHYSICAL LAYER • Maximum number of devices: DP : 126 stations/bus ( 244 bytes data limited in/out for one slave) • Communication Method: DP : peer to peer, multicast or master-slave( token pasing) PHYSICAL LAYER DATA LAYER The data layer FDL (Field bus Data Link) can be differentiated by their start delimiter (SD): No data: SD1 = 0x10 Variable length data: SD2 = 0x68 Fixed length data: SD3 = 0xA2 Token: SD4 = 0xDC Brief acknowledgement: SC = 0xE5 DATA LAYER SD: Start Delimiter LE: Length of protocol data unit Ler: Repetition of protocol data unit FC: Function Code DA: Destination Address SA: Source Address DSAP: Destination Service Access Point SSAP: Source Service Access Point PDU: Protocol Data Unit (protocol data) FCS: Frame Checking Sequence ED: End Delimiter (= 0x16 !) DATA LAYER APPLICATION LAYER FIELDBUS MESSAGE SPECIFICATION (FMS) The FMS Communication Profile is designed for communication at cell level At this level, programmable controllers (PLCs and PCs) communicate primarily with each other In this application area a high degree of functionality is more important than fast system reaction times APPLCATION LAYER PROFIBUS DP: The functions of the PRO-FIBUS DP communication protocol are distributed over three performance levels : * DP-V0 for cyclic exchange of data and diagnosis * DP-V1 for acyclic data exchange and alarm handling * DP-V2 for isochronous mode and data exchange broadcast (slaveto-slave communication) EXAMPLE ADVANTAGE Used extensively with 1,100 member companies worldwide Network support at the level of equipment, process control, and Ethernet Available interfaces for variable speed drive applications and motor control center (Profibus DP) The gateway allows integration Profibus PA directly with Profibus DP network Host interface are available for most PLC, DCS and computer systems DISADVANTAGE Profibus DP does not have Intrinsically Safe application support The requirements for wiring, power, grounding, bonding and terminal must be taken into account during the design and installation Do not use in explosive and noise environments PROFIBUS-DP PROFIBUS-PA Transmission rate: 9.6 Kbit/s – 12Mbit/s Respond time: 1-5ms Requires separate power Use RS-485 to exchange data Not intrinsically safe Transmission rate: 31.25 Kbit/s Respond time: