Patent Application
20080222662
The invention relates to a method for testing device descriptions for field devices of automation technology, as such which are executed in a frame application running on a computer unit, where the device description and the frame application communicate via an interface defined in a specification.
Field devices are commonly employed in automation technology (process automation/manufacturing automation) and serve for registering and/or influencing process variables. Examples of such field devices are fill level measuring devices, mass flow measuring devices, pressure- and temperature-measuring devices, pH- and redox-potential-measuring devices, conductivity measuring devices, etc. for process automation technology, which, as sensors, register the corresponding process variables, fill level, flow, e.g. flow rate, pressure, temperature, pH-value and conductivity value, respectively.
Serving for influencing process variables are actuators, e.g. valves, which control flow of a liquid in a section of pipeline, or pumps, which change fill level in a container.
A large number of such field devices are manufactured and sold by the firm ENDRESS+HAUSER®.
Frequently, field devices are connected with superordinated units via communication systems (PROFIBUS®, FOUNDATION-FIELDBUS®, HART®, etc.). Such superordinated units serve for process control, process visualization, device-management (configuration and servicing) and for plant management (asset management), using corresponding application programs.
The integration of field devices into such applications occurs via device descriptions. Device descriptions are provided by device manufacturers, in order that superordinated units can recognize and interpret the meaning of data supplied by the field devices.
Various device descriptions are known for the different fieldbus systems (HART-device-descriptions, Fieldbus Foundation device descriptions, Profibus device descriptions).
On the basis of cooperation of Fieldbus Foundation (FF), HART Communication Foundation (HCF) and Profibus Nutzerorganisation (PNO), an electronic device description (Electronic Device Description EDD) was created, which is defined in the standard IEC 61804-2.
With a large number of EDD-based fieldbus systems installed worldwide, EDD is a very widely used description language for device descriptions in automation technology.
For servicing field devices, corresponding servicing programs (operating tools) are necessary, which, in superordinated units, run either on their own (Endress+Hauser FieldCare, Pactware, AMS Fisher-Rosemount, PDM Siemens) or else are integrated into control system applications (Siemens PCS7, ABB Symphony, Emerson Delta V).
For a comprehensive servicing of field devices, newly, special device descriptions, so-called DTMs (Device Type Manager), are available, which correspond to the FDT (Field Device Tool) specifications. The FDT-specifications, serving as an industry standard, were developed by the PNO (Profibus Nutzer Organisation (Profibus User Organization)) in cooperation with ZVEI (Zentralverband Elektrotechnik-und Elektroindustrie (The German Electrical and Electronics Industry, a registered association)). The current FDT-Specification 1.2.1, including the Addendum for “Foundation Fieldbus” Communication, is available from ZVEI, PNO or the FDT-Group.
Many field device manufacturers already deliver corresponding DTMs for their field devices. The DTMs encapsulate all variables and functions of the pertinent field device and offer, most often, a graphical user interface for servicing the devices.
As run-time environment, the DTMs require a frame application (FDT-frame). The frame application and the corresponding DTMs permit, thus, a very comfortable access to field devices (e.g. to device parameters, measured values, diagnostic information, status information, etc.), as well as serving for invoking special functions, which individual DTMs make available.
Since field devices are serviced via DTMs, extensive function tests are needed, in order to assure that the DTMs work faultlessly in any and all frame applications. These function tests have also a safety aspect, since especially safety-critical settings can be made in field devices via DTMs.
One possibility for testing DTMs is offered by the test tool dtmINSPECTOR (M&M Software GmbH, St. Georgen). In such instance, extensive test scripts are produced, which are executed together with the DTM to be tested. Essentially, this test checks whether the DTM corresponds to the FDT-specifications (FDT interface definitions). With this test tool, in principle, it is a review only of whether the interface is working logically faultlessly. Even in the case of a successfully passed test with the help of this test tool, it is, however, not assured that the DTM will function faultlessly in all frame applications, since the sequence of the interface invocations can be different from frame application to frame application, a fact which can lead to different outcomes.
It is, therefore, necessary to test DTMs in different frame applications and, in such case, to check whether DTM and frame application each behaves correctly in the sense of the specification.
The applicant (Codewrights GmbH Karlsruhe) prepares from conventional device description files (HART, FF or Profibus), with the help of a corresponding tool (DTMstudio), device-specific DTMs in large quantities. To test the faultless functioning of each separate DTM would mean a significant test effort. But, even such extensive testing can not uncover all errors with certainty.
Moreover, there is the problem, that, in the case of malfunction, it is not at first clear, which component (DTM or frame application) is causing the error. Due to the very complex interaction between the individual components, the error analysis is often very complex and time-intensive, which, unavoidably, is associated with significant costs.
An object of the invention is, therefore, to provide a method for testing device descriptions for field devices of automation technology, which method does not have the aforementioned disadvantages, while, especially, requiring less testing effort.
This object is achieved by the provision between the frame application and the device descriptions, a first component which is transparent for the communication between frame application and device descriptions and which reviews interface invocations.
An essential idea of the invention is to provide, between frame application and device description, a test component, which is transparent for the communication between frame application and device description and which checks interface invocations for conformity with the specification.
In such case, both the device description (DTM) and also the frame application are checked for conformity.
In a further development of the invention, it is checked, whether the interface invocations are allowed according to the specification. Moreover, it is checked, whether the data transferred in the case of an interface invocation correspond to the specification.
Frequently, sequences of interface invocations are specified in interface specifications for certain tasks (e.g. storage on demand of the frame application). Therefore, in a further development of the invention, it is also checked, whether sequences of interface invocations correspond to the specifications.
In an advantageous manner, the test component is described with the help of state automata, which represent the dynamic course of events possible in the framework of the specification.
The method of the invention is suited especially for device descriptions, which, as DTMs, correspond to the FDT-specifications.
The invention will now be explained in greater detail on the basis of an example of an embodiment presented in the drawing.
For managing the project structure, each device manager and communication manager offers information via its Information interface. On the basis of this information, the frame application FA can accumulate catalog data K needed for managing the project structure. With the project structure, the frame application controls and manages also the communication paths.
The persistence of the project data is implemented by the frame application FA with the help of a Persistence interface, which are served by the device- and communication-manager instances.
Frame application FA forms, together with the device manager instances DTM1, DTM 2 and the communication manager instance DTMC, etc., an object-based configuration system CS for field devices of automation technology.
As already mentioned, the field device manufacturers make device managers available for their individual field devices. Before a field device can be accessed, the corresponding device manager, with all belonging objects, must be instantiated.
According to the invention, provided between the frame application FA and the DTMs is a test component P, which is transparent for the communication via the FDT interface between frame application and each DTM and which reviews the interface invocations.
Thus, with the help of the test component P, it is checked whether the interface invocations are even permitted by the FDT specifications.
Additionally, it can be checked with the test component P, whether the data transferred in the case of an interface invocation correspond to the FDT specifications.
With the test component P, it is also possible to check sequences of interface invocations for conformity with the FDT specifications.
From the specifications and the allowed chains of events at the interfaces, a formal model, a state automaton, is generated, on which the test component is essentially based.
With the present invention, it is possible to check for the correct interplay between a device description DTM and a frame application FA. This can be done without additional effort during the integration test, which usually must be performed. Behavior of one of the two components not conforming to specification is immediately recognized, even when this does not immediately lead to a malfunction of the total system.
In a further development of the invention, it is also possible to check all components of a more complex system having a plurality of DTMs (communication-, gateway- and device-DTMs).
The invention checks not only the logical function of the DTM interface but also the actual, concrete interplay of frame application and DTM.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2006 062 604.4 | Dec 2006 | DE | national |
