Foundation Fieldbus
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The document discusses Foundation Fieldbus, an open standard for process automation communication. It was established by the International Society of Automation to create a single international fieldbus standard. Foundation Fieldbus uses digital, serial communication between intelligent field devices. It provides wiring and installation savings, enhanced data availability, improved user interfaces, and interoperability between devices.
Foundation Fieldbus
- 2. Contents Introduction Foundation Members What is Fieldbus? FF Components FF Segment Topology Comparison Benefits Applications
- 3. Introduction Established by International Society of Automation Goal: A single international, interoperable fieldbus standard. Not-for-profit corporation Fieldbus technology is based on the work of the IEC and ISA. IEC std. for FF – IEC 61158 Fieldbus Foundation has nearly 100 member companies, which supply over 90% of the worlds instrumentation and control products.
- 5. What is Fieldbus? Fieldbus is a digital, serial two-way, multi-drop communication link among intelligent field devices and automation systems. It is an open architecture, developed and administered by the Fieldbus Foundation. H1 (31.25kbps) HSE (High Speed Ethernet)
- 6. <1930’s – Direct connected devices 1940’s – Pneumatic signal transmission 1950’s – 10-50/4-20mA replacing 3-15psi 1970’s – Process computers appear (PLCs) 1980’s – DCS implemented 1990’s – First FF systems 2000’s – Fieldbus crosses “chasm”
- 10. FF Segment Topology Point-to-point Chicken-foot (Tree) Topology Daisy chain Spur Topology Trunk Spur
- 11. Comparison
- 12. Benefits
- 15. 3. More Available Data
- 16. 4. Enhanced User Interface
- 19. One of the most important aspects of FOUNDATION fieldbus is its ability to collect and deliver vast amounts of information - not only process variables and control signals, but other types of instrument and process data as well.
- 20. Physical Layer Translating messages into physical signals on the wire - and vice versa The physical layer also provides the common electrical interface for all FOUNDATION fieldbus devices. The FOUNDATION fieldbus physical layer is defined by approved standards (IEC 61158-2 and ANSI/ISA 50.02, part 2).
- 21. Data Link & Application Layers It combines several technologies that together control transmission of data on the fieldbus. The data link and applications layers provide a standard way of "packaging" the data, as well as managing the schedule for communication and function-block execution. They enable process control while providing standardization and interoperability.
- 22. User Layer It enables user to interact with the other layers and with other applications. The user layer contains Resource blocks - describes characteristics of the fieldbus device such as device name, mfr. and serial number, etc. Transducer blocks - used to configure devices Function blocks - The Control System Strategy is built using Function Blocks. Input and output parameters of Function Blocks can be linked over the fieldbus. Device descriptions enable the host system to interact with and understand these blocks without custom programming.
- 24. Scheduled Communications All devices and function blocks on a FOUNDATION fieldbus segment execute and communicate process control information on a regular, repeating cycle. Timing for this type of communication is determined by a master schedule in a Link Active Scheduler, which is a function residing in the host system or one of the devices on the segment.
- 25. Application Clock Every device on a FOUNDATION fieldbus segment shares the same time. A system management function called the application clock periodically broadcasts the time - either local time or Universal Coordinated Time -- to all devices. Each device uses an internal clock to keep time between these synchronization broadcasts.
- 26. Link Active Scheduler The link active scheduler (LAS) function maintains the central, deterministic schedule for communication between devices on a segment. It improves overall communication reliability by compelling each device to transmit cyclic data when it's scheduled to do so.
- 27. Device Address Assignment FOUNDATION fieldbus carries signals to and from several devices over the same cable. To identify which information is associated with which device, each device is assigned an address. Depending on the communication protocol, addresses can be assigned in several ways, from dip switches or off-line addressing to automatic online assignment. Online addressing helps avoid problems such as duplicate devices with the same address, but by itself does not guarantee there are no addressing errors.
- 28. Signals Devices on a Fieldbus segment transmit digital signals to each other over the same wires that power the devices. A DC bus voltage (nominally 24V but can be from 9‐32VDC) is supplied to the devices on the segment by the Fieldbus Power Supply. A Fieldbus device draws a constant amount of current when not transmitting. To transmit information, the device varies the amount of current it draws from the segment to create a signal “riding” on the 24VDC. Digital data is sent on the Fieldbus at a rate of 31.25 Kbits/second.
- 29. Fieldbus Signal
- 30. Fieldbus Power Supply Isolator – To improve noise immunity Power Conditioner – Like a one way valve Current Limiter – Prevent damage from short-circuit or over-load conditions
- 31. Applications Refining Petrochemicals Power generation Food & beverage Pharmaceuticals Nuclear Applications
- 33. Zone-2 (Non - Incendive)
- 34. References Fieldbus Installation in a DeltaV™ Digital Automation System – Emerson Process Management QGX/20/00/IN/TS/NA/040, Rev-E2 – Foundation Fieldbus Design Specification www.wikipedia.com/foundation_fielbus