6 Reasons to Give PROFIBUS PA Another Look

Transcription

1 6 Reasons to Give PROFIBUS PA Another Look

2 #1 PROFIBUS a Proven Technology Fieldbus systems have a proven track record that goes back to the early 1990 s, and PROFIBUS has been at the forefront. These systems are deployed throughout the industrial automation landscape in the automotive, machinery manufacturing, food & beverage, pharmaceutical and chemical industries. Somewhere in the region of 50 million PROFIBUS nodes are currently installed in the field. They ensure reliable process data transport, simplify engineering design and installation, and play a key role during ongoing operation. Tailor-made PROFIBUS PA has been used in process automation for more than 10 years. Over 8 million field devices already communicate using PROFIBUS DP/PA in this arena, generating significant value-add for users. Device power and process data as well as device status signals and diagnostic data are delivered via the bus cables. Technology is not the only crucial factor. The enthusiasm, ideas, and expertise of the users and manufacturers who stand behind PROFIBUS continue to drive development. The close link between PROFIBUS & PROFINET International (PI) and end users and their organizations ensures that the technology continues to move forward while remaining aligned with application needs. Prominent examples include NAMUR, an international user association of automation technology in process industries and AIDA in the automobile industry. The result is a set of user-friendly technologies that are quickly ready for practical application. Strong organization The technology network gives users in a broad range of industries the opportunity to learn from each other. PI offers technologies for the full spectrum of industrial communication, ranging from factory and process automation to high-performance motion control applications including functional safety. The worldwide network of competence centers, training centers, and test labs ensures that support and reliable technology are available around the world. So, the potency and reliability of the cross-industry PI technology network continues to increase. PROFIBUS nodes M50 M40 M35 M30 M25 M20 M15 M10 M5

3 #2 PROFIBUS Diagnostics the Easy Way Fieldbus communication has brought about a paradigm shift in automation technology. Communication used to be one-way and each line carried only a single analog signal. Fieldbus communication uses digital technology and it is bi-directional. As a result, field devices have become an integral part of the overall system and they provide the basis for comprehensive asset management. Simple network diagnostics A fieldbus network is essentially the nervous system on the production floor and is in itself a vital asset in the automation landscape. So it makes good sense to keep an eye on the state of this asset, and nowadays nothing could be easier. A number of manufacturers offer diagnostic tools for the PROFIBUS physical layer. The choice includes mobile devices for service technicians as well as stationary equipment supplying data which can be displayed at any time in the control station, e.g. on the service console. The diagnostic tools provide valuable assistance during commissioning, maintenance, and ongoing operation. They make predictive maintenance and asset management possible in the field and from a central location. Planning with no hassle Fieldbus technology optimizes system design, configuration, and installation. Hundreds of separate cables are reduced to just a few cables or only a single one. Commissioning takes less time and device setup can be accomplished from a central location. Reversed polarity and incorrect allocation between signals and devices are a thing of the past. Every signal bears the stamp of its device and can be uniquely identified and characterized. Measurement precision is also better. The values generated in digital transducers are no longer converted to analog signals. None of the original measurement precision is lost when the data is transmitted. There is no possibility that corruption during transmission will remain unnoticed. Also, communication is not limited to process data. Diagnostic and status information allow the user to make a correct judgment on the trustworthiness of the process signals. DCS What Who Where When Why!

4 #3 PROFIBUS Device Management the Easy Way Having more information about system assets is generally an advantage assuming that the information is accurate and consistent. To provide access to more information, a few things have to be put in place at the system s engineering level. However with PROFIBUS, that is not a problem. Maintaining flexibility PROFIBUS ensures maximum flexibility for the conceptual design, engineering, and commissioning phases and guarantees uniform data structures across all devices. Integration of field devices into the automation system is based on modeling of the device functionality in the control system. The GSD (General Station Description) provided by the device manufacturer acts as the electronic data sheet for the fieldbus device. It describes all of the functionality which the device supports. Users can then select which and how much process data will be transferred. Field devices detect this automatically, adapt accordingly, and start communicating. Planning autonomy During the engineering phase, there is no need to know the details of the field devices that will be used later. A neutral channel is used to define all of the channels. Hardware engineering is device neutral and is not reliant on the field device used. The devices actually used on the system do not have to be allocated until the commissioning phase. Segregation of communication and functionality simplifies the engineering work. Defining device types Since the basic tasks of the field devices are defined back in the engineering phase, it is a good idea to preselect one of six device types for the neutral channel. Among others, the list of choices includes: Simple transmitters for one or two analog process signals, e.g. temperature, pressure or fill level Multi-functional transmitters for up to ten analog process signals, e.g. for flow metering Binary inputs and outputs Analog positions for control valves and binary positions for valve boxes In general, measurement data is transmitted as scaled values, eliminating the need for scaling (data fitting) in the control system.

5 #4 PROFIBUS for Stable Process Control Infrastructure which delivers overall stability is indispensable in the process industry, and PROFIBUS offers this level of stability for data communications in the field and at the control station. The performance features of PROFIBUS PA, which are specifically tailored to process automation, facilitate optimal solutions and enhance overall system availability. Stable, simple installation From the technical standpoint, installation of PROFIBUS PA is similar to mA. Two-wire shielded cable is used as the transmission medium. MBP (Manchester-encoded, Bus Powered) data transmission technology was developed specifically to meet the needs of process automation and has been standardized in IEC Power distribution and data transmission are implemented in a single cable. This has the following advantages when compared to traditional installations like mA: Reduced cabling cost and effort Compliance with market demand for very simple installations which are nevertheless safe and reliable Full exploitation of the advantages offered by digital data communications right down to the field device, e.g. high-precision with no drift Additional devices can easily be attached, even during ongoing operation Continuous monitoring ensures safety Users repeatedly confirm that PROFIBUS PA based communication just keeps running and running. There is good reason to trust PROFIBUS, but it is better to keep an eye on things nevertheless. State-of-the-art diagnostic tools have provided crucial operational support on PROFIBUS systems for many years, enhancing system availability. Data visualization on state-of-the-art user interfaces and automatic generation of reports on system and device status makes it easier to assess the possible need for service intervention. Impending device or network failure can be detected in time and usually prevented. The network automatically raises a flag if the quality of the installation becomes degraded. Recommended by users In many active blogs and forums, PROFIBUS users share their views on the stability and data reliability of field installations. Some argue that mA signals can be transmitted incorrectly without an error message being generated. Incorrect process data reaching the control station is interpreted as being accurate. That is virtually impossible with a digital fieldbus like PROFIBUS PA. Transmission errors are detected and reported so that corrective action can be taken. Of course instrumentation can generate incorrect signals, but even in that case there is a higher likelihood that this type of error will be detected on a fieldbus system, as every transmitted process value has its own check if calculated correctly. Every participant in a PROFIBUS network is able to send sophisticated diagnostic data which can provide an early indication of wear and other sources of error.

6 #5 PROFIBUS Certification Ensures Compatibility Billions of people use their cellphones without ever thinking about the underlying communications technology. The phones are made by different manufacturers, operate on different networks and have different user interfaces, but people can communicate no matter what phone they are using. PROFIBUS users also do not need to understand the details of the communications process, but they must have the assurance that all of the devices in operation meet certain criteria such as reliability, determinism, and compatibility. Both PROFIBUS equipment manufacturers and PI (PROFIBUS & PROFINET International) ensure that this is the case. Test labs accredited by PI perform exhaustive verification of the device s communication interface before issuing a test certificate. This procedure ensures that all of the devices speak the same language and understand each other, in other words that they conform to specification. Standards and Profiles PROFIBUS is standardized in IEC 61158, creating the framework for interoperability and compatibility. In addition, the PROFIBUS PA Profile facilitates smooth interaction between process devices on the bus. The current version V 3.02 contains many functions which make working with field devices even easier, for example device replacement. When a device is replaced, the spare device (which may well feature extended functionality) automatically assumes the role of the previous device, making device swap a simple operation which can be completed without interrupting system operation. Automatic adaptation also works with devices from different generations. The new device merely needs to support compatibility mode in compliance with Profile V Versatility A large number of manufacturers supply PROFIBUS products to the automation technology market. The product database at profibus.com currently contains more than 3,000 entries, 450 of which are specifically designed for process automation. As a result of standardization and certification, all of the devices work together without problems. Users can simply choose the device which best suits their needs without dependence on any one manufacturer. DCS

7 #6 The high-power trunk with FISCO spurs is a de-facto standard for PROFIBUS in explosion hazardous areas. Based on this concept, PROFIBUS PA can be installed without difficulty or the need for major cost analyses in the chemical, pharmaceutical, food processing, bio-gas, offshore oil production, or mining industries. The FISCO Model The FISCO Model (Fieldbus Intrinsically Safe Concept; IEC ) serves as the basis for validation of explosion protection without application-specific engineering calculations. It was developed by PTB (the German Federal Standards Laboratory) and confirms that a communication network is intrinsically safe if the components deployed (i.e. field devices, cables, segment couplers, and bus terminators) comply with predefined voltage, current, power, inductivity, and capacitance specifications. Components in accordance with FISCO fulfill these requirements. With only FISCO certified components on a segment, the validation of intrinsic safety is provided by the bill of materials. It doesn't get easier than that. FISCO, however, has limitations with respect to cable length (up to 1,000 meters) and the number of field devices that can be connected. This is where the high-power trunk comes in. The High-Power trunk PROFIBUS Simple and Safe in Hazardous Zones Ex-i Intrinsic safety with or without FISCO allows modifications of electrical systems without requiring a hot work permit. It is really only needed in process automation when intervention is required on a device during ongoing operation for maintenance purposes or when it is necessary to swap a device. At the trunk cable this is rarely necessary, thus higher power enabled with Ex-e increased safety ignition protection is normally sufficient. The High-Power Trunk concept combines elements from the Ex-e and Ex-i protection types. The trunk with Ex-e ignition protection carries high power permitting cable at lengths up to 1,900 meters and a higher number of devices. The devices are attached to fieldbus barriers and the installation is thereby FISCO compliant. With the high-power trunk, PROFIBUS PA is suitable for simple, device installation in explosion hazardous areas wherever the need arises. DCS General Purpose Area Zone 2 Class I, Div. 2 Field Barrier Field Barrier Zone 1 Class I, Div. 1/2

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