Data Acquisition Boards and USB-DAQ

Transcription

1 Data Acquisition Boards and USB-DAQ CHRISTIAN ANTFOLK Announcement Choose a project Project description deadline (you can start working on the project before that) Lab 2 will be Wednesday den kl 8-12 and

2 Structure of a measurement system Physical quantity pressure temperature speed angular velocity luminosity force Measurement system Signal conditioning DAQ-cards Bus control of instruments GPIB (parallel) RS232 (serial) Bus systems with integrated and standardized instruments VXI/PXI Real time controllers Field buses Presentation (and control) Graphical programming LabVIEW Agilent VEE DASYlab Textual programming LabWindows CVI Measurement Studio Visual Basic Visual C/C++ Matlab What is a DAQ-card 2

3 What is a DAQ (Data Acquisition Card)? Signal in A/D converter Channel (bus) Computer Bus (USB, PCI, FireWire, RS-232 etc) Speed (A/D converter & bus) Resolution Number of channels etc Example of a PCI DAQ card 4 input channels 12-bit A/D resolution One A/D per channel Analog and digital triggering 20 MHz sample rate Software selectable input ranges Dual 12-bit D/As 24-bits digital I/O 3

4 More examples of DAQ cards DAQ cards cont d 4

5 Price? Our USB DAQ-pad 14-Bit, 48 ks/s Low-Cost Multifunction DAQ 8 analog inputs (14-bit, 48 ks/s) 2 analog outputs (12-bit, 150 S/s) 12 digital I/O; 32-bit counter Bus-powered for high mobility Built-in signal connectivity OEM version available Compatible with LabVIEW, LabWindows /CVI, and Measurement Studio for Visual Studio.NET 5

6 USB-6009 inner workings USB-6009 inner workings 6

7 USB-6009 specs USB-6009 specs 7

8 USB-6009 specs USB-6009 specs 8

9 USB-6009 specs USB-6009 specs When to Use Differential Connections with Floating Signal Sources Your application requires input ranges other than ±10 V. The input signal is low level and requires greater accuracy. The leads connecting the signal to the device are greater than 3 m (10 ft). The input signal requires a separate ground-reference point or return signal. The signal leads travel through noisy environments. Two analog input channels, AI+ and AI, are available for the signal. 9

10 USB-6009 specs When to Use Differential Connections with Ground-Reference Signal Sources Your application requires input ranges other than ±10 V. The input signal is low level and requires greater accuracy. The leads connecting the signal to the device are greater than 3 m (10 ft). The input signal requires a separate ground-reference point or return signal. The signal leads travel through noisy environments. Two analog input channels, AI+ and AI, are available for the signal. USB-6009 specs When to Use Referenced Single- Ended (RSE) Connections with Floating Signal Sources The input signal can share a common reference point, GND, with other signals that use RSE. Your application permits the use of the ±10 V input range. The leads connecting the signal to the device are less than 3 m (10 ft). 10

11 USB 6009 measurements NI-6014 PCI cards also installed on computers in the lab 11

12 Dynamic range & resolution No amplification ADC 10 mvpp signal Resolution: 16-bit Dynamic range: ± 10 V 32 levels Dynamic range & resolution With amplification 10 mv signal AMP X100 ADC Resolution: 16-bit Dynamic range: ± 10 V 3200 levels 12

13 AD-converter transfer characteristics DNL Differential Non Linearity Missing code 13

14 DNL Differential Non Linearity Non monotonic INL Integreal Non Linearity 14

15 AD converter errors Noise 15

16 Noise measures SNR (Signal to noise ratio) SINAD (Signal in noise and distortion, [db]) SFDR (Spurious-free dynamic range [dbc]) ENOB (effective number of bits =(SINAD-1.76)/6.02 THD (total harmonic distortion) THD+N (total harmonic distortion + noise) SFDR 16

17 Analog Discovery 2 2 channel oscilloscope 100 MS/s 2 channel function generator 16 channel logic analyzer Single channel voltmeter Network analyzer etc Price ~ 2000 SEK Virtual Bench 2 analog channel 100 MHz BW 34 Digital Digital Multimeter Programmable DC power supply 8 Digital I/O Price ~ SEK 17