IEEE-488 Interface Research Articles

REMOTE-CONTROL MEASUREMENT SYSTEM BASED ON THE IEEE-488

The paper presents a complete system for remote measurement. The system is based on the client-server communication structure over the Internet. One part considers the client application – it is used by a user to control the measurement. Second part deals with the server – the server application itself and local connection the instruments over the IEEE-488 interface bus. The communication between client and server is built on TCP connection.

Carbon Dioxide Transport through Membranes

Several membrane channels, like aquaporin-1 (AQP1) and the RhAG protein of the rhesus complex, were hypothesized to be of physiological relevance for CO(2) transport. However, the underlying assumption that the lipid matrix imposes a significant barrier to CO(2) diffusion was never confirmed experimentally. Here we have monitored transmembrane CO(2) flux (J(CO2)) by imposing a CO(2) concentration gradient across planar lipid bilayers and detecting the resulting small pH shift in the immediate membrane vicinity. An analytical model, which accounts for the presence of both carbonic anhydrase and buffer molecules, was fitted to the experimental pH profiles using inverse problems techniques. At pH 7.4, the model revealed that J(CO2) was entirely rate-limited by near-membrane unstirred layers (USL), which act as diffusional barriers in series with the membrane. Membrane tightening by sphingomyelin and cholesterol did not alter J(CO2) confirming that membrane resistance was comparatively small. In contrast, a pH-induced shift of the CO(2) hydration-dehydration equilibrium resulted in a relative membrane contribution of about 15% to the total resistance (pH 9.6). Under these conditions, a membrane CO(2) permeability (3.2 +/- 1.6 cm/s) was estimated. It indicates that cellular CO(2) uptake (pH 7.4) is always USL-limited, because the USL size always exceeds 1 mum. Consequently, facilitation of CO(2) transport by AQP1, RhAG, or any other protein is highly unlikely. The conclusion was confirmed by the observation that CO(2) permeability of epithelial cell monolayers was always the same whether AQP1 was overexpressed in both the apical and basolateral membranes or not.

Measurement Systems and Sensors Measurement Systems and Sensors , Waldemar Nawrocki , Artech House, Norwood, MA, 2005. $95.00 (325 pp.). ISBN 1-58053-945-9

Preface. Computer-Based Measuring Systems. Electrical Thermometers. Pressure Sensors. Conditioners. Digital-to-Analog and Analog-to-Digital Converters. Measuring Systems with a Serial Interface. Wireless Measuring Systems. Measuring Systems with an IEEE-488 Interface. Cassette Measuring Systems. Virtual Instruments.

Measurement systems and sensors

Preface. Computer-Based Measuring Systems. Electrical Thermometers. Pressure Sensors. Conditioners. Digital-to-Analog and Analog-to-Digital Converters. Measuring Systems with a Serial Interface. Wireless Measuring Systems. Measuring Systems with an IEEE-488 Interface. Cassette Measuring Systems. Virtual Instruments.

Oblique saccades in visually normal human observers

Introduction: Recent evidence suggests that oblique eye movements are differentially affected by some systemic diseases (for example Graves' disease). Previous studies of eye movements have tended to concentrate on horizontal or vertical eye movements. The aim of this study is to establish baseline data (latency, duration and peak velocity) for oblique eye movement in normal human observers.Methods: Eye movements were measured using an IRIS 6500 infrared limbal eye tracker (Skalar Medical, Delft, The Netherlands) customized for the direct recording of oblique eye movements. Data were collected at a sampling rate of 205 Hz and a resolution of 0.05° using a Gould 1604 digital storage oscilloscope. Data were subsequently transferred via an IEEE488 interface bus to a PC for analysis. Ten visually normal observers recruited from the student and patient population of the University of Bradford's Eye Clinic participated in the study. Subjects made saccadic eye movements in 5° to 15° steps in horizontal, vertical and oblique orientations. Stimuli were presented in random order to ensure there was no predictable component to the response.Results: Saccadic responses to vertical and horizontal step stimuli were consistent with previous published work. The modification to the eye tracker allowed direct measurement of oblique saccades. The duration of the saccade increased as a function of stimulus amplitude and conformed to the relationship: D = D0 + dA (where D is the duration of saccadic eye movement; A is the amplitude of saccadic eye movement; d is the rate of duration increase per degree of amplitude and D0 is the y‐axis intercept of the duration vs amplitude line). Calculation of latency (∼200 ms), duration (∼80–100 ms) and peak velocity (∼300 ms−1) for oblique saccades gave responses which were similar to those reported using indirect measurement.Conclusion: A veridical measure of oblique saccadic eye movements was obtained using the modified eye tracker. Oblique responses were generally slower than for horizontal measures of saccadic eye movements. These baseline data will allow a comparison in age‐matched subjects with early onset ocular motor anomalies.

Focus on Test and Measurement

Focus on Test and Measurement

A PC-based real-time Hall probe automatic measurement system for magnetic fields [of SRRC magnets

A real-time, Hall-probe automatic measurement system was developed at the Synchrotron Radiation Research Center (SRRC) for the magnetic field measurement of the C-type rectangular combined function bending magnet, multipole magnets, and the insertion device magnets. The sampling rate on the x-y-z table with dynamic moving speed of 15 cm/s can be up to 200 samples/s, and the precision is within /spl plusmn/0.01%. A PC is used as a system controller which connects instrument function cards with instruments via the PC bus and an IEEE-488 interface card. An inexpensive, stable within /spl plusmn/15 ppm current source is produced to supply a high-stability constant current for the Hall probe; a temperature controller maintains the Hall probe temperature within /spl plusmn/0.2/spl deg/C. The system's software has been divided into different modules that can be connected into a network global data base. System testing has shown that the magnetic field measurement accuracy of this system is better than /spl plusmn/25 ppm in the static measurement.

Cryogenics

Lake Shore Cryotronics has introduced the Model 218 temperature monitor. The unit can read up to eight diode or resistance temperature sensors twice each second. All eight channels can be displayed continuously in Kelvin, Celsius, volts or ohms. The Model 218 supports a variety of sensor types, with diode sensors allowing temperature measurements down to 1.4 K. Two versions of the unit are available, one with an IEEE-488 interface and one with a serial interface. The Model 218 also features an alarm capability. Relays can be used with the alarm set-points in latching mode for error detection or in nonlatching mode for simple on/off control. The unit also includes two analogue voltage outputs, a printer interface and a data-logging facility.

An experimental setup for study of photoresponse of high T c superconductors

We have developed an experimental setup that has been proven suitable for the study of photoresponse of high Tc superconductors. The distinguish feature of this experimental setup lies mainly in the data acquisition system which is equipped with computer as well as the IEEE-488 interface bus, which ensures the accuracy to experimental results. Using the experimental setup, the optical response to laser radiation in high-Tc superconductors has been examined, both of bolometric effect and nonequilibrium optical response are revealed.

Automatic system for measuring dose - area product (DAP) in ROI fluoroscopy

A computerized system for monitoring dose - area product (DAP) has been developed for region of interest (ROI) fluoroscopy in which patient exposure is reduced using an x-ray attenuating filter with an aperture. The system includes an IBM compatible computer which is connected through an IEEE-488 interface to an electrometer which measures the charge from a DAP ionization chamber. A digital input/output board connects the computer to the filter placement device to determine whether the filter is in or out of the beam, and to the x-ray generator to determine when the exposure is due to spot filming. The computer logs the DAP from conventional fluoroscopy, ROI fluoroscopy and spot filming separately, applying the appropriate calibration factor for each. Measured DAPs, fluoroscopic DAP rates and exposure times are displayed in real-time. The system has been installed in a GI fluoroscopic room so that the dose-reduction potential of ROI imaging can be evaluated.

Methodology for teaching measuring systems

In this paper, a system approach to electrical measurement teaching is presented. This approach enables one to integrate different fields of measurements and different measurement courses. “Measuring Systems” is proposed as a main measurement course for students of Electronics Faculties. A multi-function laboratory stand for teaching measuring systems is proposed to train basic abilities in measuring system design. The stand consists of an IBM PC with an IEEE-488 (IEC-625) interface board, a bus tester, HP 33120A function generator, HP 34401A multimeter with IEEE-488 and RS-232 interface, and — optionally — a measurement plug-in card and a device with a VXI interface. Students are taught how to remote control, in a unifying way, various measuring devices with various interfaces, using simple IEEE-488 software and advanced software (LabWindows/CVI, HP VEE). The laboratory stand enables students to learn practical aspects of the design of measuring systems, teaching them the system approach to measurements.

Computer-aided transducer calibration system for a practical power system

The paper describes a new computer-aided automatic calibration system developed for the instrument calibration department of the Taiwan Power Company. One- or three-phase power transducers, including voltage, current, watt, VAr and power factor transducers, can be calibrated in this system. The generated calibration power condition is programmable. Its voltage/current amplitude and phase angle are adjustable between 0 V and 300 V, -10 A and 10 A, and 0 degrees and 360 degrees , respectively. A 386 personal computer controls all the operations inside the calibration system and interfaces with users. A menu-driven, user-friendly software interface has been developed to support the system. It offers the user flexibility of operation and ease of usage. The IEEE-488 interface bus is connected in closed-loop mode to control all stimulated equipment and the transducers under test. Special emphasis is placed on the user friendliness of this computer-aided calibration system and its capability of calibrating ten transducers using only one set-up. The experimental results for various transducers are given, and the uncertainty of the system is discussed.

Easily realized inelastic electron tunneling spectrometer

An easily realized inelastic electron tunneling spectrometer (IETS) controlled by computer through an IEEE-488 interface bus is described. Components and circuits of the system are described in detail in order to help newcomers to IETS build a research quality spectrometer on a relatively low budget. The system design is much simpler and easier to implement than others reported in the literature, and experimental results indicate that the spectrometer has comparable resolution and signal-to-noise ratio. Additionally, in-house software routines offer the system considerable flexibility in spectral data manipulation, for example, background correction, numerical differentiation, and subtraction of one spectrum from another may be performed.

Flexible, automatic test system for characterizing superconducting junctions and devices

A system has been designed for the characterizing of both low and high Tc junctions and devices. Fully automated measurements of resistance versus temperature, current versus voltage, and critical current versus applied field can be carried out on up to eight devices in one cooldown cycle. The system has been proven to reduce the repetitive nature and time involved in characterizing many junctions and devices, and greatly speeds up the analysis of changes in their parameters. Connections are made to the sample using spring contacts which eliminate the need for soldering to contact pads. One or two substrates with ten connections per substrate can be placed in the probe at the one time. A microcomputer with an IEEE488 interface, four standard instruments (two constant current sources, one digital multimeter, and one voltmeter), and a specially designed probe and software has been incorporated to provide a system which is very flexible and yet very simple to operate.

Versatile CAMAC–PC/AT system for data acquisition and control in high-resolution extreme-ultraviolet (EUV) spectroscopy following ion–atom and ion–molecule collisions

This work is related to a recent development of a data acquisition and control system for high-resolution EUV spectroscopy following ion–atom and ion–molecule collisions. The system consists of a personal computer, an IEEE-488 interface board, and a CAMAC system, which includes a GPIB crate controller, a stepping motor controller, and two 32-bit up–down counters. A unique software ‘‘DATACQ’’ for data acquisition and control has been designed and tested to simplify complex spectroscopy applications. As a prototype case, EUV spectra of the Lyman series of He+ following simultaneous ionization and excitation of He by fast H+, H+2, and H+3 impact are presented here.

Magnetic levitation using high-temperature superconductors: a materials perspective

The relationships between system parameters and material properties for a superconducting levitation (or suspension) system are investigated. A superconducting levitation measurement system, constructed to produce 5-T uniform magnetic field and approximately 1-T/cm uniform gradient in static mode, was used to measure the levitation of high-temperature superconductors. Up to 0.5 T/cm of the gradient field may also be pulsed with switching time approximately 0.1 s which was designed to perturb freely levitated superconductors in dynamic measurements. The displacement of the levitated sample was monitored using phase-sensitive inductive techniques which provided the magnitude of a magnetic force. The control of temperature and magnetic field, as well as the data acquisition, was done through an IEEE-488 interface and a 9- mu s analog-to-digital converter (ADC) using an 80386-based personal computer. The measurements and the theoretical analysis are compared. >

An automated ac-magnetic susceptibility apparatus

We report here both hardware and software for an ac susceptibility measurement system, namely the design and construction of the cryostat, coil system, sample rod assembly and also the automation of the sample rod movement, bridge control and nulling etc with the help of an inexpensive Z-80A microprocessor via a home-made IEEE-488 interface. The variable parameters are temperature, magnitude of the rms field and frequency. An entirely new dynamic bridge nulling algorithm with continuous sample movement, which eliminates to a large extent problems related to time-dependent drifts, has been developed. We also present some experimental data collected with this system.

A fast data acquisition system for in-beam nuclear spectroscopy

A GPIB-based fast data acquisition system is designed and constructed. It consists of host microcomputers, MTs, and two kinds of intelligent front-end devices, one of which is for data acquisition of singles PHA mode and the other for data acquisition of multiparameter list mode. They are connected to each other through GPIB (IEEE-488) standard interface buses. The list data are transferred not only to the MTs but also simultaneously to the host computer for on-line real-time analysis if needed. If additional capabilities of real-time analysis are required, other computers, such as a Micro-VAX, can be connected to the interface bus; this important feature of the present system is realized by the multiple-listener function of the IEEE-488 interface bus.

An instrument that isn't really (Laboratory Virtual Instrument Engineering Workbench)

The concept and development of LabVIEW (Laboratory Virtual Instrument Engineering Workbench), a virtual instrument (VI) that provides a simple, graphical way to set up and run numerous instruments on a Mackintosh PC, are described. The first concept basic to LabVIEW had its roots in a large test system comprised of programmable signal sources compatible with IEEE-488 interface specifications, and switching matrices and measurement instruments controlled by a minicomputer. The test system's strength was its flexibility, which it owed to its several levels of user interfaces. This flexible configuration was refined into the notion of instrumentation as a hierarchy of virtual instruments in which all VIs at all levels had the same type of construction. Another characteristic was that each VI have its own user interface. The final conceptual element was the use of loop data-flow structures as the technique used by an engineer to construct and run his or her own VIs. Problems encountered in the development of LabVIEW and the solutions used are discussed. >

A versatile stepping motor controller for systems with many motors

A versatile system suitable for controlling beamlines or complex experimental setups is described. The system as currently configured can control up to 32 motors, with all motors capable of full-speed operation concurrently. There are two limit-switch inputs for each motor, and a further input to accept a reference-position marker. The motors can be controlled via a front panel keyboard with display or by a host computer over an IEEE-488 interface. Both methods can be used together if required. There is an Emergency Stop key on the front panel keyboard to stop the motion of all motors without losing track of their position.