Profibus

Last updated
Profibus
PROFIBUS rgb 2010.png
Protocol Information
Type of NetworkDevice Bus, Process Control
Physical Media Twisted pair, fiber
Network TopologyBus
Device Addressing DIP switch or hardware/software
Governing BodyPROFIBUS&PROFINET International (PI)
Website www.profibus.com
Profibus electrical connector 0x-pb-stecker-verschieden.jpg
Profibus electrical connector

Profibus (usually styled as PROFIBUS, as a portmanteau for 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. [1] It should not be confused with the Profinet standard for Industrial Ethernet. Profibus is openly published as type 3 of IEC 61158/61784-1. [2]

Contents

Origin

The history of PROFIBUS goes back to a publicly promoted plan from Marco Todaro for an association which started in Germany in 1986 and for which 18 companies and institutes devised a master project plan called "fieldbus". [3] 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 FMS (Field bus Message Specification), which was tailored for demanding communication tasks, was specified. Subsequently, in 1993, the specification for the simpler and thus considerably faster protocol PROFIBUS DP (Decentralised Peripherals) was completed. Profibus FMS is used for (non-deterministic) communication of data between Profibus Masters. Profibus DP is a protocol made for (deterministic) communication between Profibus masters and their remote I/O slaves. [4] [5]

There are two variations of PROFIBUS in use today; the most commonly used PROFIBUS DP, and the lesser used, application specific, PROFIBUS PA:

In excess of 30 million PROFIBUS nodes were installed by the end of 2009. 5 million of these are in the process industries. [3]

Technology

PROFIBUS Protocol (OSI reference model)
OSI-LayerPROFIBUS
7ApplicationDPV0DPV1DPV2Management
6Presentation--
5Session
4Transport
3Network
2Data LinkFDL
1Physical EIA-485 OpticalMBP

Application layer (OSI-Layer 7)

To use these functions, various service levels [10] of the DP protocol [11] were defined: [12] [13]

The data link layer FDL (Field bus Data Link) services [15] and protocols [16] work 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. [12] [17]

Each byte has even parity and is 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

SD1 = 0x10

SD1DASAFCFCSED

Variable length data

SD2 = 0x68

SD2LELErSD2DASAFCDSAPSSAPPDUFCSED

Fixed length data

SD3 = 0xA2

SD3DASAFCPDUFCSED

Token

SD4 = 0xDC

SD4DASA

Fields

SDStart Delimiter
LELength of protocol data unit, (incl. DA, SA, FC, DSAP, SSAP)
LErRepetition of length of protocol data unit, (Hamming distance = 4)
FCFunction Code
DADestination Address
SASource Address
DSAPDestination Service Access Point
SSAPSource Service Access Point
PDUProtocol Data Unit (protocol data)
FCS Frame Checking Sequence, calculated by simply adding up the bytes within the specified length. An overflow is ignored here.
EDEnd Delimiter (= 0x16)

Service Access Points

SAP (Decimal)SERVICE
Default 0Cyclical Data Exchange (Write_Read_Data)
54Master-to-Master SAP (M-M Communication)
55Change 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.
56Read Inputs (Rd_Inp)
57Read Outputs (Rd_Outp)
58Control Commands to a DP Slave (Global_Control)
59Read Configuration Data (Get_Cfg)
60Read Diagnostic Data (Slave_Diagnosis)
61Send Parameterization Data (Set_Prm)
62Check Configuration Data (Chk_Cfg)

Bit-transmission layer (OSI-Layer 1)

Three different methods are specified for the bit-transmission layer: [9]

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 [6] uses two core screened cable with a violet sheath, [18] and runs at speeds between 9.6 kbit/s and 12 Mbit/s. [20] 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 31 devices to be connected at once; however, more devices (up to 126) can be connected or the network expanded with the use of hubs or repeaters (4 hubs or repeaters to reach 126). [7] A Hub or a Repeater is also counted as a device. [21]

PROFIBUS PA [8] runs at fixed speed of 31.25 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

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

The PROFIBUS Nutzerorganisation e.V. (PROFIBUS User Organisation, or PNO) was created in 1989. [3] 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 and 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

Related Research Articles

<span class="mw-page-title-main">CAN bus</span> Standard for serial communication between devices without host computer

A controller area network (CAN) is a vehicle bus standard designed to enable efficient communication primarily between electronic control units (ECUs). Originally developed to reduce the complexity and cost of electrical wiring in automobiles through multiplexing, the CAN bus protocol has since been adopted in various other contexts. This broadcast-based, message-oriented protocol ensures data integrity and prioritization through a process called arbitration, allowing the highest priority device to continue transmitting if multiple devices attempt to send data simultaneously, while others back off. Its reliability is enhanced by differential signaling, which mitigates electrical noise. Common versions of the CAN protocol include CAN 2.0, CAN FD, and CAN XL which vary in their data rate capabilities and maximum data payload sizes.

RS-485, also known as TIA-485(-A) or EIA-485, is a standard, originally introduced in 1983, defining the electrical characteristics of drivers and receivers for use in serial communications systems. Electrical signaling is balanced, and multipoint systems are supported. The standard is jointly published by the Telecommunications Industry Association and Electronic Industries Alliance (TIA/EIA). Digital communications networks implementing the standard can be used effectively over long distances and in electrically noisy environments. Multiple receivers may be connected to such a network in a linear, multidrop bus. These characteristics make RS-485 useful in industrial control systems and similar applications.

A fieldbus is a member of a family of industrial digital communication networks used for real-time distributed control. Fieldbus profiles are standardized by the International Electrotechnical Commission (IEC) as IEC 61784/61158.

<span class="mw-page-title-main">Industrial Ethernet</span> Use of Ethernet in an industrial environment

Industrial Ethernet (IE) is the use of Ethernet in an industrial environment with protocols that provide determinism and real-time control. Protocols for industrial Ethernet include EtherCAT, EtherNet/IP, PROFINET, POWERLINK, SERCOS III, CC-Link IE, and Modbus TCP. Many industrial Ethernet protocols use a modified media access control (MAC) layer to provide low latency and determinism. Some microprocessors provide industrial Ethernet support.

Fieldbus Foundation was an organization dedicated to a single international, interoperable fieldbus standard. It was established in September 1994 by a merger of WorldFIP North America and the Interoperable Systems Project (ISP). Fieldbus Foundation was a not-for-profit trade consortium that consisted of more than 350 of the world's suppliers and end users of process control and manufacturing automation products. Working together those companies made contributions to the IEC/ISA/FDI and other fieldbus standards development.

Foundation Fieldbus is an all-digital, serial, two-way communications system that serves as the base-level network in a plant or factory automation environment. It is an open architecture, developed and administered by FieldComm Group.

Actuator Sensor Interface is an industrial networking solution used in PLC, DCS and PC-based automation systems. It is designed for connecting simple field I/O devices in discrete manufacturing and process applications using a single two-conductor cable.

<span class="mw-page-title-main">Profinet</span> Computer network protocol

Profinet is an industry technical standard for data communication over Industrial Ethernet, designed for collecting data from, and controlling equipment in industrial systems, with a particular strength in delivering data under tight time constraints. The standard is maintained and supported by Profibus and Profinet International, an umbrella organization headquartered in Karlsruhe, Germany.

INTERBUS is a serial bus system which transmits data between control systems and spatially distributed I/O modules that are connected to sensors and actuators.

EtherCAT is an Ethernet-based fieldbus system developed by Beckhoff Automation. The protocol is standardized in IEC 61158 and is suitable for both hard and soft real-time computing requirements in automation technology.

DeviceNet is a network protocol used in the automation industry to interconnect control devices for data exchange. It utilizes the Common Industrial Protocol over a Controller Area Network media layer and defines an application layer to cover a range of device profiles. Typical applications include information exchange, safety devices, and large I/O control networks.

SafetyBUS p is a standard for failsafe fieldbus communication in automation technology. It meets SIL 3 of IEC 61508 and Category 4 of EN 954-1 or Performance Level "e" of the successor standard EN 13849-1.

Foundation Fieldbus H1 is one of the FOUNDATION fieldbus protocol versions. Foundation H1 (31.25 kbit/s) is a bi-directional communications protocol used for communications among field devices and to the control system. It utilizes either twisted pair, or fiber media to communicate between multiple nodes (devices) and the controller. The controller requires only one communication point to communicate with up to 32 nodes, this is a significant improvement over the standard 4–20 mA communication method, which requires a separate connection point for each communication device on the controller system.

Profisafe is a standard for a communication protocol for the transmission of safety-relevant data in automation applications with functional safety. This standard was developed jointly by several automation device manufacturers in order to be able to meet the requirements of the legislator and the IFA for safe systems. The required safe function of the protocol has been tested and confirmed by TÜV Süd. The PROFIBUS Nutzerorganisation e.V. in Karlsruhe supervises the standardization for the partner companies and organizes the promotion of this common interface.

WirelessHART within telecommunications and computing, is a wireless sensor networking technology. It is based on the Highway Addressable Remote Transducer Protocol (HART). Developed as a multi-vendor, interoperable wireless standard, WirelessHART was defined for the requirements of process field device networks.

The train communication network (TCN) is a hierarchical combination of two fieldbus for data transmission within trains. It consists of the Multifunction Vehicle Bus (MVB) inside each vehicle and of the Wire Train Bus (WTB) to connect the different vehicles. The TCN components have been standardized in IEC 61375.

The Factory Instrumentation Protocol or FIP is a standardized field bus protocol. Its most current definition can be found in the European Standard EN50170.

RAPIEnet was Korea's first Ethernet international standard for real-time data transmission. It is an Ethernet-based industrial networking protocol, developed in-house by LSIS offers real-time transmission and is registered as an international standard.

IO-Link is a short distance, bi-directional, digital, point-to-point, wired, industrial communications networking standard used for connecting digital sensors and actuators to either a type of industrial fieldbus or a type of industrial Ethernet. Its objective is to provide a technological platform that enables the development and use of sensors and actuators that can produce and consume enriched sets of data that in turn can be used for economically optimizing industrial automated processes and operations. The technology standard is managed by the industry association Profibus and Profinet International.

References

  1. ↑ Weigmann, Josef; Kilian, Gerhard (2003). Decentralization with PROFIBUS DP/DPV1: Architecture and Fundamentals, Configuration and Use with SIMATIC S7. Siemens. ISBN   978-3-89578-218-3.
  2. ↑ "Industrial communication networks - Profiles Part 1: Fieldbus profiles". International Electrotechnical Commission (IEC). 2019. IEC 61784-1. Retrieved 2020-04-28.
  3. 1 2 3 Bender, Klaus; Freitag, Jörg; Lindner, Klaus-Peter (2009). Milestones: PROFIBUS - 20 years of standards for industrial communication. Karlsruhe: PROFIBUS Nutzerorganisation e.V.
  4. ↑ "PROFIBUS Technology and Application – System Description". Profibus and Profinet International (PI). 2016. Order no. 4.332. Retrieved 2023-02-09.
  5. ↑ Xiu, Ji (2015). PROFIBUS in Practice: System Architecture and Design. CreateSpace Independent Publishing Platform. ISBN   978-1507633045.
  6. 1 2 Mitchell, Ronald (2003). PROFIBUS: A Pocket Guide. ISA. ISBN   978-1556178627.
  7. 1 2 "PROFIBUS Design". Profibus and Profinet International (PI). 2020. Order no. 8.012. Retrieved 2023-02-09.
  8. 1 2 Powel, James; Vandeline, Henry (2012). Catching the Process Fieldbus: An Introduction to Profibus for Process Automation. Momentum Press. ISBN   978-1606503966.
  9. 1 2 "Industrial communication networks - Fieldbus specifications - Part 2: Physical layer specification and service definition". International Electrotechnical Commission (IEC). 2022. IEC 61158-2. Retrieved 2023-02-09.
  10. ↑ "Industrial communication networks - Fieldbus specifications - Part 5-3: Application layer service definition - Type 3 elements". International Electrotechnical Commission (IEC). 2014. IEC 61158-5-3. Retrieved 2023-02-09.
  11. ↑ "Industrial communication networks - Fieldbus specifications - Part 6-3: Application layer protocol specification - Type 3 elements". International Electrotechnical Commission (IEC). 2019. IEC 61158-6-3. Retrieved 2023-02-09.
  12. 1 2 Popp, Manfred (2003). "The New Rapid Way to PROFIBUS DP - From DP-V0 to DP-V2". Profibus and Profinet International (PI). Order no. 4.072. Retrieved 2023-02-09.
  13. ↑ Xiu, Ji (2019). PROFIBUS in Practice: Standard and Operation. Independently Published. ISBN   978-1793076830.
  14. ↑ Xiu, Ji (2013). PROFIBUS in Practice: System Engineering, Trouble-shooting and Maintenance. CreateSpace Independent Publishing Platform. ISBN   978-1493614684.
  15. ↑ "Industrial communication networks - Fieldbus specifications - Part 3-3: Data-link layer service definition - Type 3 elements". International Electrotechnical Commission (IEC). 2014. IEC 61158-3-3. Retrieved 2023-02-09.
  16. ↑ "Industrial communication networks - Fieldbus specifications - Part 4-3: Data-link layer protocol specification - Type 3 elements". International Electrotechnical Commission (IEC). 2019. IEC 61158-4-3. Retrieved 2023-02-09.
  17. 1 2 3 Felser, Max (2017). PROFIBUS Manual. epubli GmbH. ISBN   978-3-8442-1435-2.
  18. 1 2 "PROFIBUS Commissioning". Profibus and Profinet International (PI). 2022. Order no. 8.032. Retrieved 2023-02-09.
  19. 1 2 Xiu, Ji (2013). PROFIBUS in Practice: Installing PROFIBUS devices and cables. CreateSpace Independent Publishing Platform. ISBN   978-1481245210.
  20. 1 2 "PROFIBUS Cabling and Assembly". Profibus and Profinet International (PI). 2020. Order no. 8.022. Retrieved 2023-02-09.
  21. ↑ "Industrial communication networks - Profiles - Part 5-3: Installation of fieldbuses - Installation profiles for CPF 3". International Electrotechnical Commission (IEC). 2018. IEC 61784-5-3. Retrieved 2023-02-09.
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