Difference between revisions of "DAQ"

Latest revision as of 14:55, 15 February 2013

Data Acquisition using Scilab

Data acquisition systems (DAQ or DAS) typically convert analog waveforms into digital values for processing.The components of data acquisition systems include: Sensors, Signal conditioning circuitry, Analog-to-digital converters, Digital to Analog Converters etc. A DAQ hardware interfaces between the analog signal and a PC. The hardware could be in the form of modules that can be connected to the computer's ports (parallel, serial, USB, etc.) or cards connected to slots (PCI, PCI-Express, etc.) in the mother board.

Most of these DAQ hardware work only on Microsoft Windows environment and they require the use of proprietary software and drivers. Here, using a set of Spoken tutorials, we teach you to access these DAQ hardware in Linux using a FOSS tool called Scilab. We have used Ubuntu Linux 10.04, kernel version 2.6.32-24. The version of Scilab required is 5.3.0 or higher. This is done with the help of HART toolbox Scilab. The DAQ hardware used in these tutorials are one among : Advantech PCI 1711, Measurement Computing PCI DAS-1002, Measurement Computing PCI-DDA8/16 and USBDUX FAST.

This tutorial will benefit students, teachers, professionals, entrepreneurs and enthusiasts who use DAQ hardware. At present, these tutorials are useful for over 100 DAQ cards listed in the COMEDI Hardware list. However, this list is growing in number.

The prerequisite for learning these tutorials is the knowledge of Scilab and knowledge of Linux - shell commands etc.

The Spoken Tutorial effort for Data Acquisition using Scilab has been contributed by Rakhi R and Abhishek Pawar from IIT Bombay.

DAQ Template

Glossary

Basic Level

1. Configuration of PC/Laptop to use DAQ with Scilab (Scripts)
   • Check the version of your kernel
   • If the kernel version is older than 2.6.30:
   • Watch tutorial on Manual Installation of COMEDI suite
   • If the kernel version is 2.6.30 or newer:
   • Install 3 packages
   • Download and install HART Toolbox in Scilab
   • Load the modules for the DAQ hardware
   • Check and verify the installation.

OR

Use this installer to install all the required software in one go! (installer files)

1. Manual Installation of COMEDI suite
   • Download Kernel source
   • Configure Kernel source
   • Download and install COMEDI packages
2. Analog input and output using PCI 1711 and Scilab in Linux (Scripts)
   • Connect the DAQ hardware
   • Load the modules for the hardware
   • Check if the hardware is recognized by the PC
   • Connect the signal you want to measure to the hardware
   • Open Scilab and HART toolbox
   • Make an Xcos diagram for analog input
   • Execute it and check the results
   • Make an Xcos diagram for analog output
   • Execute it and measure the output

Intermediate Level

1. Temperature Measurement using RTD through Scilab and PCI 1711 Data Acquisition card (Scripts)
   • Connect the DAQ hardware
   • Load the modules for the hardware
   • Check if the hardware is recognized by the PC/Laptop
   • Make the simple PCB as per the board files or:
   • Get the components to make the circuit and make it on a breadboard
   • Connect the circuit as per the Schematic diagram
   • Calibrate
   • Open Scilab and HART toolbox
   • Load the required files and execute.
   • Check the results

(circuit schematic for RTD setup) (printed circuit board for RTD setup)

1. Digital I/O using PCI-DDA 8/16 and Scilab in Linux (Scripts)
   • Connect the DAQ hardware
   • Load the modules for the hardware
   • Check if the hardware is recognized by the PC
   • Get the components to make the circuit
   • Connect the simple circuit as per the Schematic diagram
   • Open Scilab and HART toolbox
   • Load the required files and execute.
   • Check the results - LED blinking

Advanced Level

1. Writing Comedi drivers for a DAQ card (Scripts)

1. • Download the template for a basic PCI DAQ Linux driver (here)