Several software applications were written and used to operate the hardware described in the previous section. This section is a description of the software used in the research.
A software application that controlled the positioning system, the waveform generator, the power supply and the data acquisition from the CPD sensor was written in a graphical programming environment LabView (from National Instruments). The Labview environment was chosen because of the ease of use in user graphic interface designing and the availability of all necessary libraries and drivers for the Labview from the hardware manufacturer. The Labview provided hundreds of built-in libraries for advanced analysis and data visualization as well. The written application communicated with the DAQ PC card and the indexer ISA card installed in the PC to control incoming data from the CPD sensor and its motion over a sample surface. A graphic user interface was also provided to control hardware, to visualize and monitor signals and to set up measurement parameters as well. The application was used to postprocess data and visualize results of surface scanning in 2D and 3D view. A schematic diagram of the application is displayed in Figure 3.17.
Positioning system software
The positioning system manufacturer provided software routine libraries to help to develop programs for the 6400 series motion controller. These libraries were compiled in the Labview to make it usable in this environment.
Figure 3.17: Schematic diagram of the Labview application.
Using routines from compiled libraries the application communicated through the PC ISA card with the indexer to control velocity, direction and acceleration of the motion of the CPD sensor. The front panel of the positioning system module was designed to make it suitable for intuitive motion control and visualization. The sample picture of this module is shown in Figure 3.18.
Figure 3.18: Positioning system GUI module: A-motion parameter controls,
B- motion displays, C- scanning parameters controls, D- motion controls.
After activation of the module (Clicking button ON) the device operating environment was uploaded. This was the prerequisite step to connect application to the controller. The interface could be divided in four parts: motion parameter controls, motion displays, scanning parameters and limits, motion controls, Figure 3.18.
The motion parameter controls were used to fix such parameters as a velocity and an acceleration of the motion for each axis. The current position and the movement of the tables were reflected on two displays. The big display showed the XY plane of motion and the small one was used to monitor the height. The intersection of two green lines on the XY-display determined current position of the CPD probe. The units for the table positions were in mm.
From the main window, the user also could execute basic movements of the tables and defined scanning...