Data acquisition board

Splicing into the existing series of thermocouples was not attempted in order to avoid possible interference with the normal control functions of the ARC. Pressure readings were obtained by tapping directly into the pressure transducer of the ARC. In this case, an amplifier had to be interposed between the ARC and the data acquisition board in order to boost the signal. Finally, the thermocouple and the amplified pressure transducer wires were... 

Control of the peristaltic pumps is achieved using a DT 2811-PGH data acquisition board and a program written for the specific case. The card enables ordering predesigned flow-rate profiles to the pumps and reports the actual... 

Establish electrical contact for the disposable electrodes via an Ag/AgCl coated wire that was previously soldered to a Lemo connector. The galvanic cell experimental setup is shown in Fig. 2.1. Connect electrodes via a high-impedance interface (World Precision Instruments) to a 16-channel BNC block (National Instruments) coupled to a 16-bit PCI-type data acquisition board (National Instruments). Take potentials at 1-s intervals and average them (N = 250). 

A test system, controlled by personal computer (PC), was developed to evaluate the performance of the sensors. A schematic of this system is shown in Figure 3. The signals from the sensors were amplified by a multi-channel electrometer and acquired by a 16 bit analog to digital data acquisition board at a resolution of 0.0145 mV/bit. The test fixture provided the electrical and fluid interface to the sensor substrate. It contained channels which directed the sample, reference and calibrator solutions over the sensors. These channels combined down stream of the sensors to form the liquid junction as shown in Figure 1. Contact probes were used to make electrical connection to the substrate. Fluids were drawn through the test fixture by a peristaltic pump driven by a stepper motor and flow of the different fluids was controlled by the pinch valves. 

Fig. 2, Laboratory setup for combustion synthesis. 1-reaction chamber 2-sample 3-base 4-quartz window 5-tungsten coil 6-power supply 7-video camera 8-video cassette recorder 9-video monitor 10-computer with data acquisition board 11-thermocouple 12-vacuum pump ...

The temperature of the furnace is continuously varied by a temperature controller, and the outputs from the balance and from the sample temperature thermocouple are logged by a computer fitted with a 16-bit dynamic range data acquisition board. The signals are processed via a program derived using a combination of Virtual Basic and C++ and the derivative of the TGA curve is used to control the heating program via the temperature controller. 

Thermocouples were attached to the data acquisition board in a differential configuration with one lead grounded to the board. Because of the exposed nature of the thermocouple junction, care must be exercised to avoid electrical grounding of the junction, which can result in a ground loop that can... 

One maintenance anomaly occurred in January 2006. Laser power was observed to be decreasing due to a buildup film of what appeared to be water on the receiver entrance window. Laser power recovered after the window was cleaned. Another anomaly was the periodic malfunction of the data acquisition board, which was traced back to elevated ambient temperatures in the nonair-conditioned office in which the processing unit was located. 

Oxidation kinetics during air exposure after vacuum synthesis was measured using the data acquisition board L-1250 connected to a PC. The temperature coefficient of the electrical resistance in vacuum (the slope of / v(T)/f v(293K) vs. temperature) was measured after cooling of the synthesized composite from 293 to 77 K. 

A recent trend in PCs is towards legacy-free systems, which ultimately will lead to a loss of internal expansion slots. Introduction of standardized, high-speed communication ports compensates this loss. Importantly, test equipment will not be restricted for use with specific hardware or operating systems (such as plug-in data-acquisition boards). The Universal Serial Bus, USB, and IEEE-1394 (FireWire) are examples of low- (1.5-12 Mb s" ) and high-speed (up to 400Mbs ), respectively, serial communication busses that are available on modern PCs [20]. These... 

The piezoelectric sensor is then connected to a charge amplifier designed to assure an appropriate low-fiequency response to accurately di lay the relatively slow breathii movement A simple Labview program was developed to display the signal in a PC equipped with a data acquisition board. 

The development process on such systems could be fraught with complexity, so it is important to establish methods that give the designer maximum support. A very useful technique is to embed the ASIC in a PC as shown in Fig. 7.7. Data acquisition boards are used to provide intimate access to the functions of the chip. Software is developed in a portable language, such as C, which allows it to be ported onto a suitable microprocessor once it has been developed and tested [15]. This leaves the question of support software which is discussed in the following section. 

The LabVlEW program provides a graphical environment tor data acquisition from a variety of instruments, tor many different types of data analysis, and for sophisticated data presentatUm. The data-acquisition section of LabVlEW works in conjunction with the National Instruments Data Acquisition boards. Data can be acquired from plug-in boards, from USB det ices. and from Ethernet-based systems. LabVlEW allows the user to set up virtual instruments with from panels... 

One current trend in modern analytical instrumentation is to use devices lhat connect to the computer via a USB port (see Table 4-4). The USB standard allows connection of up to 127 different devices in a simple, straightforward manner. C urrently. printers, cameras, disk drives, scanners, webcams, networking components, some data-acquisition systems, and some analytical instruments are available with USB interfaces. Some devices now include a FireWire connection. With these, several devices can be connected in series (daisy-chained) so that only one FireWire port is required for multiple units. Devices that require very high-speed connections, such as the data-acquisition board shown in Figure 4-12b. still require interface lioards that connect directly to the internal computer bus. 

In order to investigate the theoretical model presented in section n, an experimental setup consisting of a water tank and piezoelectric elements is used (Figure 2). The transmitter consists of a 2 cm diameter piezoelectric transducer (PZT-4) with a resonance frequency of 1 MHz, excited by a signal generator producing a sine wave at 1.1 MHz. Another piezoelectric transducer (2 cm diameter, resonance frequency of 1.7 MHz) is connected to a data-acquisition board via a preamplifier. 

The two torque transducers, cylinder pressure transducer, liner absolute pressure transducer and two encoder signal were connected to a 12-bit high speed simultaneous sampling data acquisition system. Two National Instruments 6110E boards were used each having four analogue input channels and two 20 MHz timer/counter channels. Unlike most of the data acquisition boards the 6110E does not work in multiplex mode as each... 

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