DAQ System Desing (NI)
The main task of Data Acquisition Systems is to ensure that physical variables that cannot be calculated in hand are transferred to the computer environment with the help of sensors and conditioners . Thus, users have the opportunity to analyze very easily.
(For detailed information; http://www.ni.com/white-paper/3536/en/)
The most popular measurement types and sensors are as follows.
Strain
It is obtained by using a strain gage. Strain measurement is very sensitive and pretreatments (such as surface cleaning and fitting) must be done regularly and consciously. Pretreatment is the most difficult compared to other measurements Data Acquisition Systems. After the surface assembly is completed, it should be ensured that there is no pre-tension caused by the assembly in the structure without measuring .
(For detailed information; http://www.ni.com/strain)
Acceleration
It is mostly obtained by using IEPE (Integrated Electronic Piezoelectric) type accelerometers . IEPE type accelerometers characteristically have very high frequency response (Usually 5 kHZ or 10 kHz). Measurement ranges are very wide. Accelerometers having shock feature can measure in the range of 5000 g ~ 100000 g .
(For detailed information; http://digital.ni.com/public.nsf/allkb/E96DCCBD929EF9E886256C93006D9EC5)
Sound
It is mostly obtained with IEPE type microphones. Microphones are selected with respect to the needs of applications.
(For detailed information; http://www.ni.com/white-paper/14349/en/)
Force
It is obtained by using Loadcell . They are mostly sensors with a strain gage based measurement principle. Loadcell output is proportional and rate is determined by the manufacturer during the calibration processes after production. For example; calibration values include values such as 2.05 mV/V or 3.18 mV/V. In other words, 2.05 mV or 3.18 mV output is get for each 1 V value given as supply. Let's assume that the loadcell capacity is 1000 N and the bias supply value is 10 V. In this case, if the loadcell output voltage is 10.25 mV, we can say that the applied force is 500 N.
(For detailed information; http://www.futek.com/load_cell_selection.aspx)
Transfer
As well as measuring with several types of sensors, the most commonly preferred types are analog/digital tachometers and tape sensors. Tape sensors calculate the cycle by counting the pulses caused by the reflection of the black/white stripes adhered to the rotating part. Outputs are TTL type and can be used in systems with digital inputs.
Tachometers are of two types as analog or digital outputs. Depending on the application, one can calculate the revolution by counting the pulses from the 24 V NPN / PNP output, which is the digital output of a proximity sensor, and an encoder with a TTL output will do the same. Any type of digital output can be selected depending on the ease of assembly, measurement accuracy and measurement speed. Also it is available with SPI and SSI output models.
Analog outputs are as diverse as digital outputs. Open sensors which are potentiometric and output voltage according to the supplied voltage can be used. In addition, there are also models with contactless 4-20 mA analog output.
As it has many types, tachometers should be selected for application and sensor output.
(For detailed information; http://zone.ni.com/reference/en-XX/help/372416B-01/svtconcepts/tacho_sig/)
Data Acquisition System hardware is determined according to the content of test and measurement applications. At this stage, depending on the application, which platform (NI cDAQ, NI cRIO or PXI) will be selected, the modules are selected. Since the system is completely modular, it is sufficient to take only the module (there must be room for the additional module in the chassis) for an additional future application.
As AnsoLab Elektronik , we can design the system that you need from scratch using the above knowledge and experience we have.
