BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI - Universitatea ...

Bul. Inst. Polit. Iaşi, t. LVI (LX), f. 2, 2010 99
Transducer was chosen and the whole system was built base on
recommendations from the literature [3] – [5].
Part of the measure is placed on two supports adjustable so that it can be
defined by two points equal height verification. This determines a straight line,
to which will determine the actual right - edge play. For measurement: using
an inductive transducer type Hottinger Baldwin Messtechnik WA T-10mm,
supplied with 20 V DC voltage from a source Hameg HM 8040-2. Output is
taken from a data acquisition card National Instruments USB 6009.
Measurement chain is completed with a PC. No other mode of signal
conditioning is required. Virtual instrument was developed programming
environment LabVIEW 8.2 Student Edition.
The block diagram of the application is presented in Fig. 2 [6] and involves
the DAQ Assistant Express VI, the Waveform Chart for displaying the
acquired signal and also the Build Table and the Write to Measurement File
blocks for writing the acquired signal values in a table and in a file for further
analysis.
Fig. 2 – The block diagram of the application [6].
The DAQ Assistant may be founded in the Express Functions palette of
the block diagram and it is needed to create and configure a task that reads a
voltage level in a specified range from a DAQ device. After the DAQ Assistant
is placed on the block diagram, a dialog box window is launched in order to
configure the data acquisition system. The dialog box displays a list of channels
of the installed DAQ device and from this list the physical channel to which the
instrument connects the signal must be selected. The others configurations are
related to terminal configuration (differential or single ended), acquisition mode
(continuous or not), signal input range and rate of acquisition. The Write to
Measurement File Express VI is used for storing the information about the data