Profi Lab-Expert: Application for PC Data Acquisition Cards

Published:2011/8/3 2:24:00 Author:Amy From:SeekIC

By Hans Koerfer, Kolter Electronic

The field of measurement, control and process technology is now dominated in the professional arena by PC-based data acquisition cards. The spectrum of applications is covered by digital I/O cards, relay cards, A/D and D/A converter cards, as well as cards offering a combination of these features. The cards are available in a range of variants from a number of different manufacturers. Although the selection of a card on the basis of its suitability for the project and price-performance ratio is straightforward, the problems start when considering which software will provide the most economical, simple, quick and flexible solution. Data acquisition cards come equipped with only the minimum ’intelligence’ required to make them work as universally as possible.

Some software companies offer suitable programming environments for driving PC data acquisition cards and for visualizing the results. There is a small number of very specialized data acquisition applications that demand particularly powerful and hence very expensive develop­ment systems, but for everyday requirements there are generally programming environments available that are not too costly and that do not make any sacrifices in terms of user-friendliness or flexibility. A graphical pro­gram development environment, such as that offered by ProfiLab-Expert, is essential. As well as being reasonably priced, it also offers the further advantage that the pro­gramming environment is easy to understand and free of exotic functions. The user can quickly find their way around the component library and tools available, and rapidly become familiar with the software.

A powerful programming environment

At around one hundred Euro (about sixty pounds) Profi­Lab-Expert is an inexpensive and yet powerful program­ming environment that can be used in a multitude of data acquisition projects, whether they involve analogue meas­urements, digital controls, or some combination of the two. Almost any monitoring, regulation or control func­tion can be realized without having to write a single line of program code. Given its features and price, the pro­gramming environment should also be of interest to schools: the program offers on easy-to-use simulation function which allows the construction of virtual logic cir­cuits (Figure 1). The program offers a graphical programming environment with a symbolic display. For example, a circuit can be wired up on the screen as a block diagram. Items can be selected from an extensive library of electronic func­tional units from switches and various logic functions to complete data acquisition cards, placed in the work area using ’drag and drop’, and then wired up.



If a particular component requires configuration settings, these can be entered on a component-by-component basis using the ’Properties’ dialogue accessed from the context menu.

The controls and monitor points of the circuit are placed in an additional window (Figure 2) imitating a front panel. The layout of the individual control and display elements can be freely chosen, and can be annotated if required. The characteristics (appearance and range) of the elements can be configured if desired or as needed. Using the front panel the simulation or actual application can be started and then monitored and controlled using the various elements.



Despite the complexity of the software, it is very simple to use: after just a little familiarization operation soon becomes intuitive. The components needed for the project can be found in the extensive library, which includes all the logic and arithmetic elements needed to combine and process signals. The library includes not only logic com­ponents such as gates, flip-flops, counters, registers, ROMs and RAMs, but also instrumentation components such as trigger circuits, formula boxes, sample-and-hold units, comparators and so on. A wide range of modules for displaying results is also available: from light-emitting diodes, analogue meters, digital displays and tables for showing measured values all the way up to X-Y plotters and oscilloscopes.

Data acquisition cards from various manufacturers can be incorporated into the component library. Each of these data acquisition cards appears as a normal compo­nent (Figure 3) with all its connections: the user just needs to wire up the desired inputs and outputs. The PC will now simulate the circuit in real time at the click of a button. Incoming measured values are processed or dis­played, and outgoing signals are generated. Incorporat­ing a data acquisition card just requires entering the I/O address, adding the desired control and monitor compo­nents and wiring the external connections (Figure 4). Developing the project is just like drawing a circuit dia­gram. The needed components are simply dragged from the library into the working window and then wired up as required. The individual components can be combined in any way desired.





The simulation can then be started to test the function in real time. It is possible to interact directly with the system using the front panel controls. Also, the current state of the components (for example whether a switch is open or closed) and signal flow can be superimposed on the circuit diagram. All incoming measured values and signals are processed and displayed immediately. The simulation can be halted at any time to make changes to the circuit. A bonus feature of the development environment is a compiler which can take a completed project and turn if into a stand-alone application. The resulting application can then run on any Windows PC without having to install ProfiLab.

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