Analog Data Acquisition System Using Virtual Instruments Computer Science Essay

Data acquisition is a great demand in industry and consumer applications. Data acquisition involves garnering signals form measurement beginnings and digitising the signal for storage, analysis and presentation on a personal computing machine ( Personal computer ) . The intent of informations acquisition is to mensurate an electrical or non-electrical ( physical ) phenomenon such as electromotive force, current, temperature, force per unit area, heat, visible radiation or sound. Computer-based informations acquisition implements a combined hardware like informations acquisition card, package, and a personal computing machine to mensurate the physical information.

Data acquisition systems integrated signals, detectors, signal conditioning, informations acquisition devices, and application package.

Multichannel informations acquisition ( DAQ ) is needed in many real-time applications for the intent of surveillance, monitoring, and/or control. These applications include wideband communications, bid communicating and control, infinite geographic expedition, medical diagnosing, etc. In our proposed system multichannel DAQ is implemented utilizing practical instrumentality package LABVIEW. If the signals are at the same time acquired, coincident acquisition of extra informations can be used to obtain extra information within the same acquisition clip [ 1 ] .

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However, bing computing machine based multi-channel DAQ systems are rugged, expensive and necessitate expensive instruments. To cut down cost and power ingestion of bing computing machine based DAQ an embedded system based DAQ was designed. An embedded system is a special-purpose computing machine system which is a combination of hardware and package designed to execute one or a few dedicated maps utilizing microcontrollers and microprocessors frequently with real-time calculating restraints.

Embedded systems when employed into the informations acquisition environments can accomplish low cost, low power ingestion and portability but this besides has few disadvantages [ 2, 3 ] .

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An embedded system has nevertheless it is non reconfigurable due to its fixed hardware architecture [ 4 ] , [ 5 ] . Fixed architecture embedded microcontroller DAQ systems have many disadvantages. It is non easy for a user to replace the design as per demands as in instance of embedded based DAQ system. If an bing DAQ system uses one processor with 16 spots, for illustration, there are times when it is needed to heighten the public presentation by utilizing two processors with 32 spots each. In such instances it will be required to replace the whole embedded microcontroller DAQ system with a new one.

Further, the size of the cache of a microcontroller is a design parametric quantity that can non be reconfigured after fiction. In add-on, infixing drifting point operations, or altering the ALU functionality is non possible. Besides, in fixed architecture DAQs, hardiness, and mistake tolerance are achieved by redundancy. This in bend increases the size, power ingestion and the cost of the system. The proposed system uses the installations of Data acquisition system utilizing practical instruments which eliminates the usage of physical instruments.

system architecture

Multichannel DAQ is performed to get the channels at the same time without intervention. The importance of multichannel DAQ is observed in many

Fieldss [ 6 ] . The intent of acquisition of many channels has much impact in biomedical and infinite applications [ 7 ] .

Signal Parameters

Demultiplexing Channelss

Clustering Channels Analog inputs

Multiplexing Channelss

Multichannel Waveform

Fig. 1 Block Diagram of DAQ utilizing Virtual Instrumentation

Figure 1 shows the block diagram of DAQ implemented in Labview utilizing practical instruments. The parallel channels are acquired in practical instruments. Each channel is analysed with signal parametric quantities like amplitude, frequence and multiplexed. The multiplexed signals are stored and displayed in multichannel. Thus multichannel is acquired in a individual wave form and instead the signal parametric quantities can be varied. This method has a greater advantage that a accountant can easy supervise and command the channels at the same time.

The aim was to plan the DAQ System to aim the recent demands in the industries and do it compatible with the new tendencies in the engineering and to cut down the cost restraints. The use of the installations, flexiblenesss and the available resorts to fit the demands is targeted in the design. This undertaking is designed with maintaining in head the recent tendencies of applications and its demands along with the cost restraints. There are certain other ends which are targeted through this design which are as included like industrial application, low-cost to little graduated table Industries, system can take topographic point of systems based on monitoring temperature, force per unit area, humidness, degree, sound, heat, pH electromotive force.


By and large DAQ system ever has a commanding unit or the processing unit. Function of this unit is to get the informations and change over it to the useable format. The practical instruments is capable of taking informations and responsible for giving end product in intentional scope of parallel input i.e. within mention electromotive force bounds. Signal conditioning of the detector signals are to be carried out before it could be connected to the system. Computer manipulates the information every bit good as shops it in a file, therefore it besides does map of informations logging [ 8 ] . The system as a whole classified in two primary design faculties as, temperature acquisition and other physical informations acquisition like force per unit area, sound, pH, degree etc with GUI ( Graphical User Interface ) based package for show of acquired informations by package tool LabVIEW.


The rapid promotion and acceptance of computing machines in the last two decennaries has given a great betterment in instrumentality trial and measuring. Continuous decrease of personal computing machines and handiness of low cost high public presentation package bundles has boosted the systems for Automatic Test Equipment ( ATE ) based on programmable instrumentality. GPIB ( General Purpose Interface Bus ) based programmable instrumentality has gained enormous spread in the last decennary for planing ATE system with the construct of & A ; acirc ; ˆ?virtual instrumentality & A ; acirc ; ˆA? . Virtual Instruments ( VI ) replace portion of acquisition of informations, treating the information every bit good as show, in traditional instruments, by utilizing personal computing machine. By graphical scheduling, the computing machine proctor can be turned into the front panel of the physical instruments and, in fact, with extra characteristics. Plug-in data acquisition cards acts as interface between computing machine and outside universe, it functions as a device that is capable of digitizes incoming parallel signals [ 10 ] .

General VI is defined as the combination of hardware and package with industry-standard computing machine engineerings to make user-defined instrumentality. In this type of trial instrumentality that is fundamentally package reliant and chiefly dependent on a computing machine to command trial hardware and equipment, analyze, and present trial consequences. The power of VI application package lies in the fact that it empowers the user to include trial equipments as objects in their plans.

Virtual instrumentality which uses extremely productive package, modular I/O used in commercial platforms. An organisation named National Instruments introduced LabVIEW, a practical instrumentality package developed for graphical execution of instruments, uses symbolic representations to implement the graphical scheduling for velocity operations and development. The package symbolically represents maps [ 10 ] . Another advantage of practical instrumentality constituent is that modular input/output which is designed to be quickly combined in random or any measure to guarantee that practical instrumentality can be implemented and can supervise and command any development facet.


The parallel inputs are acquired ab initio utilizing practical instruments. In LabVIEW many practical instruments like switch, boss, metre etc are implemented in order to avoid utilizing traditional instruments in informations acquisition. All the channels are grouped in a individual block called bunch.


Fig. 2 Cluster Block Diagram position

Figure 2 shows the construction of a bunch in block diagram. The above construction shows the execution of all informations types like whole number, Boolean etc. , in a individual bunch. It combines different informations types within a individual construction. It reduces the connexion terminuss to stand in VI.


Fig. 3 Cluster Front Panel position

Figure 3 shows the construction of bunch in front panel. The chief bunch operations bundle, unbundled, bundle by name and unbundle by name. The following are the bunch operations.

Extraction of single informations types from bunch.

Addition of single informations elements to a bunch which consequences in a group of informations types.

Interrupting a bunch into its single informations types like boolean, drifting point etc.


Proposed system uses temperature acquisition as a separate faculty. Here the temperature is acquired utilizing practical instruments and it is measured. Acquisition of temperature is utile in many applications like conditions prediction, infinite applications and +medical applications.


Fig. 4 Temperature Acquisition

Figure 4 shows the temperature acquisition utilizing practical instruments. Here the temperature is acquired with the aid of metre. Initially the random informations is recorded utilizing metre and the information is varied. The recorded information is displayed in thermometer. The user can easy supervise the assorted alterations happening in the thermometer and displayed in the wave form. Using the show, the user can observe the mistakes and command the fluctuations.


Multiplexing plays an of import function in multichannel DAQ. Here it groups the signal of changing amplitude and frequence and displayed in the wave form. Multiplexing is the procedure of scanning through figure of input channels and trying in each rotary motion [ 9 ] . Multiplexing allows individual ADC to make the work of several channels. Rather than giving a ADC to each channel, a individual converter can be used with the aid of multiplexing. This can salvage power, as ADC uses important sum of power than switches does.

Unbundle operation performs demultiplexing of practical channels. Hence it is demultiplexed utilizing unbundling map. This splits the assorted signal parametric quantities and given as input to map generator.

Table I Comparison Table Among Existing DAQ Systems


Computer Based DAQ

Microcontroller Based DAQ


Labview DAQ

DAQ Hardware





Reconfigurable Hardware





Hardware Complexity







High cost due to fixed architecture

Moderate cost

Low cost






No power ingestion


Applicable in real-time


High public presentation

Full capablenesss of FPGA,

Single multiplexed ADC,

Hardware scalability

Increased public presentation,

Graphic manner to get channels.

Easy measuring undertaking.

In Table I it is shown that the proposed system is more advantageous than bing system interms of cost and hardware complexness. The public presentation is higher in practical channels than in physical channels. Alternatively of utilizing physical instruments, many practical instruments can be used which enables easier control and measuring undertaking.


The multichannel DAQ system have shown that many channels can be controlled at the same time as per user demands. The proposed system uses practical instruments to command and supervise the channels with low cost.

Labview simulation consequences can be viewed in front panel. Here the eight channel acquisition is split up into four wave forms in which each contains two channel wave form. The linguistic communication used for scheduling is labVIEW besides called as G, is a dataflow scheduling linguistic communication. The plan executing is determined by the construction of a block diagram on which the coder connects differeny function-nodes by pulling wires. These wires propogate variables and any node can put to death when all its input informations is available. Since multiple cringles execute when all input informations available, G is capable of put to deathing parallel executing. This characteristic makes of LabVIEW helps in planing multichannel informations acquisition.

two channel waveform.png

Fig. 5 Two Channel Wave form

Figure 5 shows the two channel wave form which shows the acquisition of informations utilizing two practical channels. The amplitude degree can be varied harmonizing to the entrance informations. The wave form chart shows the fluctuation in incoming informations and it can be easy controlled by the user.


Fig. 6 Multichannel DAQ System

Figure 6 shows the full simulation consequences of proposed system. It has four wave form charts in which each contain two channel wave forms. The signal parametric quantities like amplitude, frequence and signal type is given as input to the basic map generator. The map generator changes the end product harmonizing to the input. The multichannel wave form is applied for assorted input. The discrepancy in signal parametric quantities depends on signal input. Based on the amplitude and frequence value the multichannel wave form is obtained. This attack is utile in medical diagnosing. To get and analyze ECG signals and to analyze and human generated signals which are of different amplitude and frequence this attack can be implemented.

Each channel acquisition consists of assorted parametric quantities and adjusted to user demands. Temperature acquisition is done alone utilizing virutal instruments. The temperature discrepancy can be viewed clearly in front panel.


The conceptual design of multichannel DAQ utilizing practical instruments has been provided. Using practical instrumentality technique eight channel data acquisition is obtained. The channels are multiplexed in a multichannel wave form and figure of channels can be displayed in a individual wave form. Multichannel DAQ is cosmopolitan and it is applied in assorted countries like wideband communicating, radio detection and ranging application, medical and environmental applications. The chief maps of the DAQ portion have been designed, built. The stand-alone DAQ has good public presentation. The device cost is merely a fraction of bing multichannel DAQs. The execution of DAQ in Soc FPGA is the topic of future paper which implements the advantage of utilizing reconfigurable hardware.

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Analog Data Acquisition System Using Virtual Instruments Computer Science Essay. (2020, Jun 01). Retrieved from

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