The datalogger is a project carried out by two students of a technical High School in Vienna. The main aim of this project is to invent a device that is able to measure signals of as many sensors as possible at the same time. Afterwards these measurements are processed by a microprocessor. To get a nearly exact illustration of the physical value, the data has to be multiplied by different factors. The reason for these multiplications is that the signals of nearly every sensor consist of voltages that are representative of the physical values. The factors the data is multiplied by are defined in a configuration file that is stored on a USB-stick. The microprocessor recognizes these factors, converts the measured data and saves the modified values on the USB-stick.
Afterwards the file that contains the measured values can be opened by importing it into software called Excel. By using this software the data can be transformed into a tablet or a graph.
To guarantee the mobility of the datalogger the whole application is supplied by a 9V battery that is fixed inside the box. Furthermore nearly all components of the printed board are SMD (surface mounted device) components. These components are very small so that the box can be very small as well.
In contrast to the USB - Application, which needs a supply voltage of 5V, the microprocessor only needs 3V supply voltage which means that two different voltages have to be generated. The datalogger also has many outputs like two analog outputs, two pulse width modulation outputs and four digital outputs. The datalogger can create a 0 - 3,3V output signal that is regulated by a pulse width modulation. That means that you can choose between a constant analog output and a constant pulse width modulation. The latter outputs are used to control inductive or capacitive sensors. Because of the mobility the datalogger can also be used outdoors. That means that every single component of the casing has to have a protection category of IP65 or higher.