Application of Ethernet Powerlink for communication in a Linux RTAI open CNC control system

In computerized numerical control (CNC) systems, the communication bus between the controller and axis servo drives must offer high bandwidth, noise immunity, and time determinism. More and more CNC systems use real-time Ethernet protocols such as Ethernet Powerlink (EPL). Many modern controllers are closed costly hardware-based solutions. In this paper, the implementation of EPL communication bus in a PC-based CNC system is presented. The CNC system includes a PC, a software CNC controller running under Linux Real-Time Application Interface real-time operating system and servo drives communicating via EPL. The EPL stack was implemented as a real-time kernel module. Due to software-only implementation, this system is a cost-effective solution for a broad range of applications in machine control. All software systems are based on GNU General Public License or Berkeley Software Distribution licenses. Necessary modifications to the EPL stack, Linux configurations, computer basic input/output system, and motherboard configurations were presented. Experimental results of EPL communication cycle jitter on three different PCs were presented. The results confirm good performance of the presented system

Układ sterowania CNC bazujący na komputerze PC z magistralą EtherCAT

W artykule przedstawiono układ sterowania numerycznego maszyn zbudowany na bazie komputera PC, komunikujący się z serwonapędami i układami wejścia/wyjścia sterującymi wyposażeniem maszyny poprzez magistralę komunikacyjną EtherCAT. W komputerze zaimplementowano system operacyjny czasu rzeczywistego Linux RTAI wraz ze zmodyfikowanym oprogramowaniem sterującym LinuxCNC. Opracowano programowy moduł komunikacyjny magistrali EtherCAT i zintegrowano go z oprogramowaniem LinuxCNC. Opracowany moduł EtherCAT umożliwia komunikację z serwonapędami zgodnie ze standardem CiA 402 oraz modułami wejść/wyjść zgodnie ze standardem CiA 401. Opracowany układ sterowania cechuje się prostą budową i łatwym montażem. Pozwala na bardzo szybką dwukierunkową komunikację z napędami i układami wejścia/wyjścia. Jest układem elastycznym, który można łatwo zaimplementować do sterowania maszynami wieloosiowymi o różnej konfiguracji

The n–Si/p–CVD Diamond Heterojunction

Due to the possible applications, materials with a wide energy gap are becoming objects of interest for researchers and engineers. In this context, the polycrystalline diamond layers grown by CVD methods on silicon substrates seem to be a promising material for engineering sensing devices. The proper tuning of the deposition parameters allows us to develop the diamond layers with varying crystallinity and defect structure, as was shown by SEM and Raman spectroscopy investigations. The cathodoluminescence (CL) spectroscopy revealed defects located just in the middle of the energy gap of diamonds. The current–voltage–temperature, I−V−T characteristics performed in a broad temperature range of 77–500 K yielded useful information about the electrical conduction in this interesting material. The recorded I−V−T in the forward configuration of the n–Si/p–CVD diamond heterojunction indicated hopping trough defects as the primary mechanism limiting conduction properties. The Ohmic character of the carriers flux permitting throughout heterojunction is intensified by charges released from the depletion layer. The magnification amplitude depends on both the defect density and the probability that biasing voltage is higher than the potential barrier binding the charge. In the present work, a simple model is proposed that describes I−V−T characteristics in a wide range of voltage, even where the current saturation effect occurs

Orientation Dependence of Cathodoluminescence and Photoluminescence Spectroscopy of Defects in Chemical-Vapor-Deposited Diamond Microcrystal

Point defects, impurities, and defect–impurity complexes in diamond microcrystals were studied with the cathodoluminescence (CL) spectroscopy in the scanning electron microscope, photoluminescence (PL), and Raman spectroscopy (RS). Such defects can influence the directions that microcrystals are grown. Micro-diamonds were obtained by a hot-filament chemical vapor deposition (HF CVD) technique from the methane–hydrogen gas mixture. The CL spectra of diamond microcrystals taken from (100) and (111) crystallographic planes were compared to the CL spectrum of a (100) oriented Element Six diamond monocrystal. The following color centers were identified: 2.52, 2.156, 2.055 eV attributed to a nitrogen–vacancy complex and a violet-emitting center (A-band) observed at 2.82 eV associated with dislocation line defects, whose atomic structure is still under discussion. The Raman studies showed that the planes (111) are more defective in comparison to (100) planes. What is reflected in the CL spectra as (111) shows a strong band in the UV region (2.815 eV) which is not observed in the case of the (100) plane

The Barrier’s Heights and Its Inhomogeneities on Diamond Silicon Interfaces

In this work, the electrical parameters of the polycrystalline diamonds’ p-PCD/n-Si heterojunction were investigated using temperature-dependent current–voltage (I-V) characteristics. In the temperature range of 80–280 K, the ideality factor (n) and energy barrier height (φb) were found to be strongly temperature dependent. The φb increases with temperature rise, while the n value decreases. The observed dependencies are due to imperfections at the interface region of a heterojunction and the non-homogeneous distribution of the potential barrier heights. Values of the φb were calculated from I-V characteristics using the thermionic emission theory (TE). The plot of φb versus 1/2 kT revealed two distinct linear regions with different slopes in temperature regions of 80–170 K and 170–280 K. This indicates the existence of a double Gaussian distribution (DGD) in heterojunctions. Parameters such as mean barrier heights φ¯b and standard deviations σ were obtained from the plots linearization and read out from intercepts and slopes. They take values φ¯b = 1.06 eV, σ = 0.43 eV, respectively. The modified Richardson plot is drawn to show the linear behavior in these two temperature ranges, disclosing different values of the effective Richardson constants (A*)