Many different methods are used nowadays for level and flow measurement. The rapid advance made in intelligent sensor technology now provides users with an enormous number of functions for controlling their industrial processes. Accordingly, the requirements that instrumentation and control engineers are expected to meet have increased tremendously in the last few years. Considering the different operating philosophies adopted by the various manufacturers, the majority of users find it very difficult to make the most of the functionality of all sensor systems in use. Many manufacturers of intelligent field devices, in the past, have failed to optimise operator control in the interests of the user.
Krohne took this up as a challenge when developing its new level and flow measuring devices. With the launching of the new Optiflux, Optiflex and Optiwave series, the company has worked at improving the interface by with intelligent and well thought-out wizard and diagnostic systems.
Krohne has been developing and producing radar and TDR level measuring devices since the mid-1980s. In the process it has proven itself in the field and earned recognition in the market. The new Optiflex and Optiwave level measuring devices are intelligent 2-wire TDR and radar devices (FMCW radar, 24 GHz), respectively, with numerous metrological features, allowing level measurement and interface detection of practically all liquids, liquefied gases and solids, even under extreme conditions. This is only achievable with high dynamic ranges, large bandwidths and, in the case of radar, the FMCW radar measuring process.
Local operator interface
Ease of operation begins with selecting the right operator controls and displays. Krohne opted for a large, high-contrast graphic display for the display of its new measuring devices, allowing representation of information in both alphanumeric and graphic form. This makes interactive communication easier during start-up and makes data readings easier during operation. The operating elements are four piezoelectric pushbuttons that allow parameters to be set from the outside.
Advances were made with device functionality and in the design of the display images for user convenience. The aim was to enable the operator to start up the device without any need for previous knowledge or experience. So an interface was created to allow the exchange of information between man and sensor.
The heart of this system is a quick set-up wizard. During parameterisation, this tutor system provides a lot of additional information on every single input parameter including; for example, the graphic representation and valid range of parameter values.
If the operator fails to input anything for a pre-set time (during the setting up procedure) additional graphic and textual information is automatically made available to help clear up any points in question. As a check, the user is given a summary of all inputs made. After acknowledgement, the data is accepted as a parameter set in the device configuration.
Device functionality includes the possibility of indicating and printing out measured values in standardised or user-defined units (eg, for manufacturer-specific packing units or rare or 'exotic' units of measurement). For this purpose, the signal converter provides the possibility of describing the tank geometry. Here, the most common tank shapes can be selected and dimensioned, and even the angle of inclination (eg, of horizontal cylinders) can be taken into consideration. The conversion software, operating in the background, then automatically creates an error correction curve for volume or mass with up to 50 points, the various extreme points being distributed intelligently over the measuring range (as a function of the tank shape).
A large number of display options are available for the measured values. These include the purely numerical representation of the measured value and also numerical representation with a stylised tank or bar graph. Echo curves and reflection spectra can also be displayed in the measuring range. Several measured values, eg, level and interface, can be displayed simultaneously.
The signal converters are able to communicate with users in the most commonly spoken languages: German, English, French and Spanish, plus Italian, Portuguese, Japanese, Russian and Chinese. Safety mechanisms have also been built into the device firmware, including the possibility of using a 'hot key' to switch from one particular language to the default language (English). This will be of help, for example, to service technicians when parameterising the devices in faraway places; in such cases fluency in any particular foreign language would not be necessary.
Failsafe software update of firmware
Any necessary software updates can be carried out on a menu-driven basis. Customised firmware or new extended-function firmware can be loaded in the interactive mode. This is normally carried out via communication with a commercial PC using device-specific PACTware DTMs. The update is carried out as a 'failsafe update'. The intelligence of the failsafe functionality is located in the signal converter and will ensure the safe startup of the device. Startup following an update is vitally important. The essential point is that two firmware revision levels must be in place simultaneously.
Should communication between PC and device be faulty during data transfer or should the data record be transferred incompletely or incorrectly, the device can still be started up with the 'old' instead of the updated software.
Conclusion
The development work carried out by manufacturers of field devices has not changed. What has changed, are the requirements, demands and needs for operator control of the sensors. Whereas device functionality and optimisation of production costs were formerly of prime importance, the more important aspects now are 'ease of use' or 'ease of handling'. The development of intelligent operator interfaces calls for market- and user-oriented demand analyses and interdisciplinary teamwork.
The handling quality stems from software ergonomics with well thought-out interactive structures without losing sight of the user. How the user feels in the parameter-setting situation is usually discovered very early on in the test phases. Development work on Krohne's new measuring devices culminated in signal converters with efficient and innovative operator control structures that meet the demands of the users.
For more information contact Kruben Bennie, Krohne, 011 315 2685, kruben@krohnesa.co.za
| Tel: | +27 11 314 1391 |
| Fax: | +27 11 314 1681 |
| Email: | salesza@krohne.com |
| www: | www.za.krohne.com |
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