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PROFIBUS (Process Field Bus) is a standard for fieldbus communication in automation technology and was first promoted in 1989 by BMBF (German department of education and research) and then used by Siemens. It should not be confused with the PROFINET standard for Industrial Ethernet. PROFIBUS is openly published as part of IEC 61158. Contents 1 Origin 2 Technology 2.1 Application layer 2.2 Security layer 2.2.1 No data 2.2.2 Variable length data 2.2.3 Fixed length data 2.2.4 Token 2.2.5 Fields 2.2.6 Service Access Points 2.3 Bit-transmission layer 3 Profiles 4 Organization 5 See also 6 References 7 External links Origin[edit]
The history of PROFIBUS goes back to a publicly promoted plan for an
association which started in Germany in 1986 and for which 21
companies and institutes devised a master project plan called
"fieldbus". The goal was to implement and spread the use of a
bit-serial field bus based on the basic requirements of the field
device interfaces. For this purpose, member companies agreed to
support a common technical concept for production (i.e. discrete or
factory automation) and process automation. First, the complex
communication protocol
Profibus
PROFIBUS DP (Decentralised Peripherals) is used to operate sensors and actuators via a centralised controller in production (factory) automation applications. The many standard diagnostic options, in particular, are focused on here. PROFIBUS PA (Process Automation) is used to monitor measuring equipment via a process control system in process automation applications. This variant is designed for use in explosion/hazardous areas (Ex-zone 0 and 1). The Physical Layer (i.e. the cable) conforms to IEC 61158-2, which allows power to be delivered over the bus to field instruments, while limiting current flows so that explosive conditions are not created, even if a malfunction occurs. The number of devices attached to a PA segment is limited by this feature. PA has a data transmission rate of 31.25 kbit/s. However, PA uses the same protocol as DP, and can be linked to a DP network using a coupler device. The much faster DP acts as a backbone network for transmitting process signals to the controller. This means that DP and PA can work tightly together, especially in hybrid applications where process and factory automation networks operate side by side. In excess of 30 million PROFIBUS nodes were installed by the end of 2009. 5 million of these are in the process industries. Technology[edit] PROFIBUS Protocol (OSI reference model) OSI-Layer PROFIBUS 7 Application DPV0 DPV1 DPV2 Management 6 Presentation -- 5 Session 4 Transport 3 Network 2 Data Link FDL 1 Physical EIA-485 Optical MBP Application layer[edit] To use these functions, various service levels of the DP protocol were defined: 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 (slave-to-slave communication) Security layer[edit] The security layer FDL (Field bus Data Link) works with a hybrid access method that combines token passing with a master-slave method. In a PROFIBUS DP network, the controllers or process control systems are the masters and the sensors and actuators are the slaves. Each byte is secured with an even parity and transferred asynchronously with a start and stop bit. There may not be a pause between a stop bit and the following start bit when the bytes of a telegram are transmitted. The master signals the start of a new telegram with a SYN pause of at least 33 bits (logical "1" = bus idle). Various telegram types are used. They can be differentiated by their start delimiter (SD): No data[edit] SD1 = 0x10 SD1 DA SA FC FCS ED Variable length data[edit] SD2 = 0x68 SD2 LE LEr SD2 DA SA FC DSAP SSAP PDU FCS ED Fixed length data[edit] SD3 = 0xA2 SD3 DA SA FC PDU FCS ED Token[edit] SD4 = 0xDC SD4 DA SA Fields[edit] SD Start Delimiter LE Length of protocol data unit, (incl. DA,SA,FC,DSAP,SSAP) LEr Repetition of length of protocol data unit, (Hamming distance = 4) 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, calculated by simply adding up the bytes within the specified length. An overflow is ignored here. ED
End
Delimiter
Service Access Points[edit] SAP (Decimal) SERVICE Default 0 Cyclical Data Exchange (Write_Read_Data) 54 Master-to-Master SAP (M-M Communication) 55 Change Station Address (Set_Slave_Add) - SAP55 is optional and may be disabled if the slave doesn't provide non-volatile storage memory for the station address. 56 Read Inputs (Rd_Inp) 57 Read Outputs (Rd_Outp) 58 Control Commands to a DP Slave (Global_Control) 59 Read Configuration Data (Get_Cfg) 60 Read Diagnostic Data (Slave_Diagnosis) 61 Send Parameterization Data (Set_Prm) 62 Check Configuration Data (Chk_Cfg) Bit-transmission layer[edit] Three different methods are specified for the bit-transmission layer: With electrical transmission pursuant to EIA-485, twisted pair cables with impedances of 150 ohms are used in a bus topology. Bit rates from 9.6 kbit/s to 12 Mbit/s can be used. The cable length between two repeaters is limited from 100 to 1200 m, depending on the bit rate used. This transmission method is primarily used with PROFIBUS DP. With optical transmission via fiber optics, star-, bus- and ring-topologies are used. The distance between the repeaters can be up to 15 km. The ring topology can also be executed redundantly. With MBP (Manchester Bus Powered) transmission technology, data and field bus power are fed through the same cable. The power can be reduced in such a way that use in explosion-hazardous environments is possible. The bus topology can be up to 1900 m long and permits branching to field devices (max. 60 m branches). The bit rate here is a fixed 31.25 kbit/s. This technology was specially established for use in process automation for PROFIBUS PA. For data transfer via sliding contacts for mobile devices or optical or radio data transmission in open spaces, products from various manufacturers can be obtained, however they do not conform to any standard. PROFIBUS DP uses two core screened cable with a violet sheath, and runs at speeds between 9.6 kbit/s and 12 Mbit/s. A particular speed can be chosen for a network to give enough time for communication with all the devices present in the network. If systems change slowly then lower communication speed is suitable, and if the systems change quickly then effective communication will happen through faster speed. The RS485 balanced transmission used in PROFIBUS DP only allows 126 devices to be connected at once; however, more devices can be connected or the network expanded with the use of hubs or repeaters. PROFIBUS PA is slower than PROFIBUS DP and runs at fixed speed of 31.2 kbit/s via blue sheathed two core screened cable. The communication may be initiated to minimise the risk of explosion or for the systems that intrinsically need safe equipment. The message formats in PROFIBUS PA are identical to PROFIBUS DP. Note: PROFIBUS DP and PROFIBUS PA should not be confused with PROFINET. Profiles[edit] Profiles are pre-defined configurations of the functions and features available from PROFIBUS for use in specific devices or applications. They are specified by PI working groups and published by PI. Profiles are important for openness, interoperability and interchangeability, so that the end user can be sure that similar equipments from different vendors perform in a standardised way. User choice also encourages competition that drives vendors towards enhanced performance and lower costs. There are PROFIBUS profiles for Encoders, Laboratory instruments, Intelligent pumps, Robots and Numerically Controlled machines, for example. Profiles also exist for applications such as using HART and wireless with PROFIBUS, and process automation devices via PROFIBUS PA. Other profiles have been specified for Motion Control (PROFIdrive) and Functional Safety (PROFIsafe). Organization[edit] The PROFIBUS Nutzerorganisation e.V. (PROFIBUS User Organisation, or PNO) was created in 1989. This group was composed mainly of manufacturers and users from Europe. In 1992, the first regional PROFIBUS organisation was founded (PROFIBUS Schweiz in Switzerland). In the following years, additional Regional PROFIBUS & PROFINET Associations (RPAs) were added. In 1995, all the RPAs joined together under the international umbrella association PROFIBUS & PROFINET International (PI). Today, PROFIBUS is represented by 25 RPAs around the world (including PNO) with over 1400 members, including most if not all major automation vendors and service suppliers, along with many end users. See also[edit] Computer networking portal Computer Science portal Fieldbus List of automation protocols References[edit] profibus.com, PROFIBUS system description J. Weigmann, G. Kilian: Decentralization with PROFIBUS DP/DPV1, ISBN 978-3-89578-218-3 M. Felser: PROFIBUS Manual, A collection of information explaining PROFIBUS networks assembled by Prof. Max Felser, ISBN 978-3-8442-1435-2 External links[edit] PROFIBUS & PROFINET International PROFIBUS Manual by Prof. Max Felser - on-line version v t e
Automation
Process automation AS-i BSAP CC-Link Industrial Networks CIP CAN bus CANopen DeviceNet ControlNet DF-1 DirectNET EtherCAT Ethernet Global Data (EGD) Ethernet Powerlink EtherNet/IP Factory Instrumentation Protocol FINS FOUNDATION fieldbus H1 HSE GE SRTP HART Protocol Honeywell SDS HostLink INTERBUS MECHATROLINK MelsecNet Modbus Optomux PieP Profibus PROFINET IO RAPIEnet SERCOS interface SERCOS III Sinec H1 SynqNet TTEthernet Industrial control system MTConnect OPC DA OPC HDA OPC UA Building automation 1-Wire BACnet C-Bus CEBus DALI DSI DyNet Factory Instrumentation Protocol KNX LonTalk Modbus oBIX VSCP X10 xAP xPL ZigBee Power-system automation IEC 60870 IEC 60870-5 IEC 60870-6 DNP3 Factory Instrumentation Protocol IEC 61850 IEC 62351 Modbus Profibus Automatic meter reading ANSI C12.18 IEC 61107 DLMS/IEC 62056 M-Bus Modbus ZigBee Automobile / Vehicle AFDX ARINC 429 CAN bus ARINC 825 SAE J1939 NMEA 2000 FMS Factory Instrumentation Protocol FlexRay IEBus J1587 J1708 Keyword Protocol 2000 Unified Diagnostic Services LIN MOST VAN v t e Technical and de facto standards for wired computer buses General System bus Front-side bus Back-side bus Daisy chain Control bus Address bus Bus contention Network on a chip Plug and play List of bus bandwidths Standards SS-50 bus
S-100 bus
Multibus
Unibus
VAXBI
MBus
STD Bus
SMBus
Q-Bus
Europe Card Bus
ISA
STEbus
Zorro II
Zorro III
CAMAC
FASTBUS
LPC
HP Precision Bus
EISA
VME
VXI
VXS
NuBus
TURBOchannel
MCA
SBus
VLB
PCI
PXI
HP GSC bus
InfiniBand
UPA
PCI Extended (PCI-X)
AGP
PCI Express
Infinity Fabric Intel UltraPath Interconnect Storage ST-506
ESDI
IPI
SMD
Parallel ATA
Parallel SAS Fibre Channel
SATAe
PCI Express
Peripheral Apple Desktop Bus
DCB
HP-IL
HIL
MIDI
RS-232
RS-422
RS-423
RS-485
DMX512-A
IEEE-488
Audio ADAT Lightpipe AES3 Intel HD Audio I²S MADI McASP S/PDIF TOSLINK Portable PC Card ExpressCard Embedded Multidrop bus CoreConnect AMBA Wishbone SLIMbus Interfaces are listed by their speed in the (roughly) ascending order, so the interface at the end of each section should be the fastes |
