In the past, field devices proved that there could be too much of a good thing, transferring large amounts of diagnostic information that virtually flooded the user with data. NAMUR, a European group of approximately 15,000 process control experts, has written a document to help developers deal with this flood of information. NE 107, self-monitoring and diagnostics of field devices, outlines a series of recommendations on how to drive reliability and provide fieldbus diagnostic data using contextual presentation created for the people and systems that need it.
NE 107 compresses the diagnosis into four standard status functions. The availability of clear and well-structured data has considerable advantages to plant operators and maintenance personnel. Users now receive only the information that they actually need instead of getting thousands of superfluous measurement details. That eliminates many uncertainties related to plant operation and fault elimination. "The standardized diagnostics in accordance with NAMUR recommendation NE 107 permits a change from the previous maintenance strategy of rigid, cyclical and often unnecessary intervals to flexible maintenance as required. Device integration can thus save a large amount of money," explains Juan Garcia, product manager at Vega.
FDT Technology is the ideal technology for those tasked with utilizing diagnostics with the added value achieved with NE 107. FDT Technology is the globally accepted standard (IEC 62453, ISA103, and China National Standard GB/T 29618) for communications and integration of smart field devices across protocols and applications spanning different manufacturers. The combination of the two specifications can help developers and operators exploit the diagnostic functions in modern networked or fieldbus devices. The FDT Group has incorporated the use of the NE 107 symbolism in their style guide.
"One of the seven autonomous networks in our sewage treatment plants is used specially for communication with the intelligent field devices, making information available for asset management, engineering and maintenance", explain Hans Wolfgang Frank and Lars Fenner, who manage process technology at Stadtentwässerung und Umweltanalytik Nuremberg. “FDT Technology enabled us to implement a standardized, engineering environment, independent of the device manufacturer, for parameterization and commissioning of all field devices. It allows us to access the field devices from as many points in our plant as possible.”
FDT is comprised of two main components to enable device integration and operational management. One is the Device Type Manager (DTM), which contains device-specific data, functions and logic elements for smart devices. Another is the Frame Application, which serves as the visual interface, allowing plant operators to view and communicate with smart devices through the device DTM. It’s through device integration and maintenance technology like FDT that enables smart instrumentation, across networks the ability to funnel NE107 diagnostic reporting that provide a proactive maintenance approach with clear meaning. Below are four examples that demonstrate the improvements that can be gained when NAMUR NE 107 and FDT Technology are combined to collect and analyze device and network diagnostics.
Diagnosis According to Customer Request
Endress+Hauser focuses on several open standards to meet customer requirements for categorized diagnostic messages. "Our DTMs for all HART, Profibus and FOUNDATION fieldbus devices have a standardized diagnostic module, which implements the NE 107 consistently and independently of the communication protocol on the basis of the fieldbus specifications", says Sandra Wesner, Head of Technology Marketing at Endress+Hauser Process Solutions. "Users thus receive exactly the information they require in order to react quickly and correctly."
The measuring technology from Endress+Hauser is state-of-the-art and implements specification extensions for standardized diagnostic messages of the field buses in a consistent manner in the devices such as the FOUNDATION field bus, FF-912 and with Profibus Profile 3.02. After opening the device DTM, the dynamic diagnostic information is displayed automatically in FDT-based Plant Asset Management Tools, such as FieldCare from Endress+Hauser. It consists of a human-readable fault message, data describing the possible cause of fault and exact instructions for action. With this information, even inexperienced users can make a diagnosis and often correct faults without operating instructions or detailed knowledge of the device.
Clever Devices
Being able to see a wealth of information can help companies improve efficiency and reduce down time. Vega’s radar systems gather large volumes of diagnostic data, making it easier to maintain systems. "Our sensors carry out continuous, internal monitoring and diagnostic functions,” said Vega’s Garcia. “The results of these activities, together with the four defined NE 107 statuses – maintenance requirements, function check, failure and outside the specification – are available to the process control system in the form of a compressed diagnosis message." If maintenance is required, the responsible personnel can then request more detailed information from the sensor in a targeted manner via the corresponding sensor DTM and, where necessary, introduce suitable measures. If, for example, the signal-to-noise ratio of a plics® radar sensor from Vega becomes smaller and smaller, the reason for this could be material adhesions on the antenna. Cleaning the antenna can then be planned in a targeted manner.
Modern technology such as radar, provides many options for routines and checks that help users to optimize processes in their plants. Targeted querying of the device status can be carried out by means of the available DTMs via FDT Frame Applications, such as the free, operating software independent of manufacturers and fieldbus for the configuration and parameterization of field devices, PACTware.
The use of a larger measured value memory allows data to be acquired and saved on site at the sensor. Vega’s new plicsplus device generation is provided with an event and diagnosis memory for logging operations. All of this is combined with a unique time code. For fault analysis, for example, echo curves can be saved and analyzed after reading out the memory.
Monitoring Made Easy
Although two thirds of all users believe that continuous monitoring of fieldbus networks is absolutely necessary, only a few have implemented it up to now. Users may buy equipment with the finest device diagnostics, but many of the benefits will be lost if the diagnostic information cannot reach the process control system because there are problems with the network.
Wherever continuous and reliable operation is required, installing a fieldbus system should be a focal point. A fieldbus failure can have serious consequences, so the bus segment should have a high quality, high availability installation. "The fieldbus topology of the FOUNDATION fieldbus H1 and Profibus PA becomes a controllable plant component with the help of diagnostic tools such as the Advanced Diagnostic Module (ADM) that includes NE107 network status reporting. The fieldbus is now a lot easier to handle“, states Thomas Westers, who handles training in process automation at Pepperl+Fuchs. "All information is available via the DTM in the safe environment of the control room. Entry to the plant is unnecessary, which enhances personal and plant safety.”
Automated test tools are used for installation inspection and monitoring. They can perform a loop check using the perfectly functioning communication as a basis. The ADM from Pepperl+Fuchs offers high operating comfort, carries out inspections of the fieldbus topology, documents the connected field devices, logs deviations and can compare them with the planning document. The ADM uses an expert system to precisely indicate irregularities in the installation using simple, comprehensible text. Typical installation errors such as inadequate shielding, grounding errors, incorrect termination or short circuits can be remedied quickly.
Standardized and User-friendly
Trebing+Himstedt offers a cross-network monitoring system for Profibus, Profinet, EtherNet/IP, Modbus TCP and Industrial Ethernet. Networks can be monitored during operation with TH Scope web-based software. When combined with network access via the Profibus-Ethernet gateway TH Link, the software detects malfunctions very early. The diagnostic software can monitor several fieldbus networks and communication protocols in an application and will report standardized NE 107 functional diagnostics making facility maintenance easy. "Standardized, modern and user-friendly operating concepts for asset management systems are indispensable", says Katja Große, responsible for Marketing Industrial Communication at Trebing+Himstedt. "The application offers not only central access to different field devices from the FDT Frame Application, but also plant-wide, parallel monitoring of fieldbus and field devices. All of this is available without additional effort."
The user benefits from a standardized diagnostic system for different fieldbus protocols and receives support with commissioning, operation, inventory and maintenance. Users do not require special knowledge of the communication protocols. That’s because errors in the network and devices are shown quickly using intuitive operating interfaces. Other tools include automatic alarm signaling for errors or problems and a simple display based on a traffic light.
Operational efficiency is key to plant potential. The benefits gained by these diverse implementations underscore the value of using FDT Technology to access network and field device diagnostics with harmonized NAMUR NE 107 status reporting. When technologies are easy to implement, users can utilize them quickly and improve their operations.
