Student Projects
DATA ACQuISITION SYSTEM
Authors
Nguyen Van Binh - BSc
Nguyen Minh Duc - BSc
- NI Labview 8.5
- NI Visa 4.3
In reality, there are many signals we have to measure and store such as the signals of temperature, humidity, pressure… in hydrometeorology; voltage signals and electric current in electric. We need a system to do this function. Because these signals are non electricity, we have to change them to want to measure them into electric signals so we can make the measurement.
After receiveing these signals, DAQ system can measure them and send them to computer to store or calculate.
The Challenge
Data - Collecting and treating system will collect the voltage signals in 0-5V range, convert them to digital correlatively to 10-bit ADC. Then these signals will be sent to computer with maximum speed. The computer uses Labview 8.5 to draw and display the signals on the screen so user can view clearly. Beasides, the signals will be stored in hard disk. System has some other abilities: create sin, pulse, triangle signal with changeable frequency; sets output with 0-1 value to control other devices by roles.
Solution
This system uses NI labview 8.5 to create communicating software between hardware and computer. System also use NI Visa 4.3 to make USB communication with maximum speed. In designing hardware, PIC18F4550 was used because of it’s ability not only to make USB communication but also convert analog signals to digital signals with 10-bit ADC.
Abstract
This system will automatically measure the signals, convert analog to digital then send results to computer. The computer receives these signals and draws graph and warms user if there is any signal over or lower a standard value.
Firstly, signals will be converted to electric signal using sensors. Then signals will be amplified with voltage standard from 0 to 5V.
After that, signals will be sent to hardware. The hardware uses PIC18F4550 mirco controller with compiler CCS 4.057. They do the following works:
- Convert analog signal to digital using ADC integrated in micro controller.
- Send signals including 9 channels using USB communication.
USB communicating Module is integrated in PIC18F4550. All programmer has to is to set this communication and transform the signals. When signals are sent to computer by USB communication, the next work is create a software with ability to receive and decoder these signals. NI Labview 8.5 and NI visa 4.4 are suitable for this mission. Figure 1 is interface design on NI labview 8.5:
Figure 1: Front Panel of DAQ.
Figure 2: LabVIEW Block Diagram.
The signals which was sent to computer will be decodered and divided to 9 channels. When many signals was sent, system will draw graph including measured time and value. Beasides, keep an eye on storing with SAVE modul, warming user when something goes wrong and printing any graph.
Beside collecting signals, system also create standard voltage such create sin, pulse, triangle signal with changeable frequency; sets output with 0-1 value to control other devices from the screen.
Figure 3: Types of signal can be created from system.
Future Development
In the future, this system can use internet or wifi communication and integrate some common sensors such as measuring temperature with signal amplifies to be able to receive signal from environment and receive larger voltage range. Another development is system will be embedded by Labview runs separate with computer. System will measure signals and store into its hardware. Treating these signals can be done directly in hardware via LCD or computer.
Conclusion
DAQ system collects signals and sends them to computer by USB communication. It really useful for supervising, measuring,warning system.
For more information, please contact:
Nguyen Van Binh, hanoi-vietnam
Tel: +84-0957539488/ +84-04-38845745
Email: binh_bk_2008@yahoo.com
Nguyen minh duc, haiduong-vietnam
Tel: +84-0946337742
Email: minhduchutedu@gmail.com
