Telemark University College Department of Electrical Engineering, Information Technology and Cybernetics NI USB-6008 DAQ Device
HANS-­‐PETTER H ALVORSEN, 2 013.08.16 Faculty of Technology,
Postboks 203, Kjølnes ring 56, N-3901 Porsgrunn, Norway.
Tel: +47 35 57 50 00
Fax: +47 35 57 54 01
Table of Contents
Table of Contents .................................................................................................................................... ii 1 Introduction ...................................................................................................................................... 1 2 System Description ........................................................................................................................... 2 2.1 Documentation ......................................................................................................................... 3 3 Configuration .................................................................................................................................... 4 3.1.1 Testing the USB-­‐6008 in MAX ............................................................................................ 4 3.2 Creating Tasks ........................................................................................................................... 9 4 Using NI USB-­‐6008 in LabVIEW ....................................................................................................... 10 4.1 DAQ Assistant .......................................................................................................................... 11 4.1.1 Analog Input ..................................................................................................................... 11 4.1.2 Analog Output .................................................................................................................. 18 ii 1 Introduction
NI USB-­‐6008 is a simple and low-­‐cost multifunction I/O device from National Instruments that will be used in Lab Work at Telemark University College (TUC). The NI USB-­‐6008 is a USB based data acquisition (DAQ) and control device with analog input and output and digital input and output. 1 2 System Description
NI USB-­‐6008 is a simple and low-­‐cost multifunction I/O device from National Instruments. The device has the following specifications: •
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8 analog inputs (12-­‐bit, 10 kS/s) 2 analog outputs (12-­‐bit, 150 S/s) 12 digital I/O USB connection, No extra power-­‐supply neeeded Compatible with LabVIEW, LabWindows/CVI, and Measurement Studio for Visual Studio .NET NI-­‐DAQmx driver software The main features of NI USB-­‐6008 are as follows: •
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Analog input (AI): 8 inputs with referenced single ended signal coupling or 4 inputs with differential signal coupling. Software-­‐configurable voltage ranges: ±20V, ±10V, ±5V, ±4V, ±2.5V, ±2V, ±1.25V, ±1V. Max sampling rate is 48kS/s (48000 samples per second). 12 bits AD converter. Analog output (AO): 2 outputs. Voltage range is 0 -­‐ 5V (fixed). Output rate is 150Hz (samples/second). 12 bits DA converter. Digital input (DI) and digital output (DO): 12 channels which can be used as either DI or DO (configured individually). These 12 channels are organized in ports, with Port 0 having lines 0, .., 7, and Port 1 having lines 0, .., 3. Input low is between -­‐0.3V and +0.8V. Input high is between 2.0V and +5.8V. Output low is below 0.8V. Output high is above 2V. 2 3 •
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System Description Counter: 32 bits. Counting on falling edge. On-­‐board voltage sources (available at individual terminals): 2.5V and 5.0V Power: USB-­‐6008 is powered via the USB cable. You may use different Development Software when working with the NI USB-­‐6008 device, e.g., LabVIEW, C, or Visual Studio. You may also use the device on different Platforms, such as Windows, Mac and Linux. This document will focus on using LabVIEW for Windows. 2.1
Documentation
The documentation for the NI USB-­‐6008 DAQ device is as follows: •
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NI USB-­‐6008 Data Sheet NI USB-­‐6008 User Guide NI-­‐DAQ mx for USB Devices These documents are available from www.ni.com or from my Blog: http://home.hit.no/~hansha/ Lab Equipment: NI USB-6008 DAQ Device
3 Configuration
Configuring and testing: USB-­‐6008 can be configured and tested using MAX (Measurement and Automation Explorer), which is installed with the NI-­‐DAQmx Driver Software. The first time you connect the USB-­‐6008 to the PC, the Windows Hardware Installer Wizard will open. The wizard searches the PC for the necessary driver software for the USB-­‐6008. This driver software was installed along with the installation of the NI-­‐DAQ software. When the wizard has finished the installation of the driver software, the USB-­‐6008 is ready for use. 3.1.1 Testing the USB-6008 in MAX
Before you start to use the USB-­‐6008 in an application, you should test the device in the Measurement and Automation Explorer (MAX). In the MAX window, expand the “Devices and Interfaces” node and then “NI DAQmx Devices”. Right-­‐click on the NI USB-­‐6008 device and select “Self-­‐Test”. 4 5 Configuration Hopefully the self-­‐test passes without errors. Then, you should test the individual channels of the USB-­‐6008 to check that the input signals are detected correctly by the USB-­‐6008, and that the output signals generated by the USB-­‐6009 have correct values. This I/O can be tested in several ways, depending on which channels you actually want to test. We will perform a simple loopback test: Here, let us test analog output channel 0 (AO0) and the analog input channel 0 (AI0) to see if they work correctly. We will perform a very simple test, which is sufficient if we are to check that both AO0 and AI0 work correctly. The test procedure, which is denoted loopback, is to connect the AI0 channel to the AO0 channel. Then we generate some legal voltage at AO0. If AI0 detects the same voltage, we know that both AO0 and AI0 work. (We may then repeat this procedure for other channels.) If for some reason AI0 detects some other voltage than the value we set for AO0, then there is an error in either the AI0 channel or in the the AO0 channel, and further investigations are necessary. To prepare for the loopback test, we wire together AI0 and AO0. To see the terminals of the USB-­‐6000, select “Device Pinouts” from the right-­‐click menu. Lab Equipment: NI USB-6008 DAQ Device
6 The Figure shows the AI0 and AO0 channels wired together. Lab Equipment: NI USB-6008 DAQ Device
Configuration 7 Configuration To actually perform the loopback test, right-­‐click on the NI USB-­‐6008 device in MAX, and then select “Test Panels..” in order to open the Test Panels. In the Test Panels window, select the Analog Output tab. Figure 11: The Voltage Output dialog window in the Test Panels window
In the Analog Output tab, select any voltage between 0V and 5V. Next, click the Analog Input tab in the Test Panels window. Lab Equipment: NI USB-6008 DAQ Device
8 Configuration The Analog Input tab should indicate the same (or almost the same) voltage as is set out on AO0. There may be a small difference between the values due to the limited resolution in the DA-­‐converter (digital-­‐to-­‐analog) and in the AD-­‐converter (analog-­‐to-­‐digital). Lab Equipment: NI USB-6008 DAQ Device
9 3.2
Configuration Creating Tasks
In general, a task represents the configuration of the signal input or signal output operation to be executed by the I/O device. Creating tasks is a general feature of the MAX utility, i.e., tasks are used also for configure other I/O devices than the USB-­‐6008. In general, a task can contain one or more global or local virtual channels, and one such virtual channel is based on one physical channel (having e.g. a screw terminal on the I/O device). A local virtual channel exists only within its parent task, while a global virtual channel may be used in several tasks. If a global channel is reconfigured, all tasks which involve that global channel are updated accordingly. In the following it described how to create tasks for the analog input and the analog output operations. These tasks may be referred to in the application program, e.g. LabVIEW. Lab Equipment: NI USB-6008 DAQ Device
4 Using NI USB-6008 in
LabVIEW
In order to use the NI USB-­‐6008 in LabVIEW you need to use the DAQmx functions, see Figure below. DAQmx – Data Acquisition palette: 10 11 4.1
Using NI USB-­‐6008 in LabVIEW DAQ Assistant
The easiest ways is to use the DAQ Assistant. 4.1.1 Analog Input
When you drag the DAQ Assistant icon on your Block Diagram, the following window appears: In this window you need to select either “Acquire Signals” (i.e., Input Signals) or “Generate Signals” (i.e., Output Signals). Lab Equipment: NI USB-6008 DAQ Device
12 Using NI USB-­‐6008 in LabVIEW Select Acquire Signals → Analog Input → Voltage. In the next window you select which Analog Input you want to use. Select ai0 (Analog Input channel 0) and click Finish. The following window appears: Lab Equipment: NI USB-6008 DAQ Device
13 Using NI USB-­‐6008 in LabVIEW In the Timing Settings Select “1 Sample (On Demand)”. Lab Equipment: NI USB-6008 DAQ Device
14 Using NI USB-­‐6008 in LabVIEW The next step is to select the Signal Input Range. A common signal is 0-­‐5V. You may also rename the name of the channel (right-­‐click on the name): Lab Equipment: NI USB-6008 DAQ Device
15 Using NI USB-­‐6008 in LabVIEW You are now finished with the configuration. Click OK in the DAQ Assistant window The DAQ Assistant icon appears on the Block Diagram: Lab Equipment: NI USB-6008 DAQ Device
16 Using NI USB-­‐6008 in LabVIEW Example: Wire the data output to a numeric indicator like this (and hit the Run button): Then numeric indicator will show, e.g., the following value: Example: If you want a continuous acquisition, put a While loop around the DAQ Assistant like this: However you should not use the DAQ Assistant inside a loop because of the lack of performance. The following is therefore better: Lab Equipment: NI USB-6008 DAQ Device
17 Using NI USB-­‐6008 in LabVIEW In this example we have used some of the other Vis in the DAQmx paletter as well. The Front Panel may loook like this. In this example we assume that we connect wires for Analog Out and Analog In together like this (a socalled loopback test): Lab Equipment: NI USB-6008 DAQ Device
18 Using NI USB-­‐6008 in LabVIEW An alternative method without using the DAQ Assistant is follows: For more advanced applications this is the recommended approach. [End of Example] 4.1.2 Analog Output
Analog Output is similar. Lab Equipment: NI USB-6008 DAQ Device
19 Using NI USB-­‐6008 in LabVIEW Lab Equipment: NI USB-6008 DAQ Device
20 Using NI USB-­‐6008 in LabVIEW Example: Or inside a loop: Lab Equipment: NI USB-6008 DAQ Device
21 Using NI USB-­‐6008 in LabVIEW An alternative method without using the DAQ Assistant is follows: For more advanced applications this is the recommended approach. [End of Example] Lab Equipment: NI USB-6008 DAQ Device
Telemark University College Faculty of Technology Kjølnes Ring 56 N-­‐3918 Porsgrunn, Norway www.hit.no Hans-­‐Petter Halvorsen, M.Sc. Telemark University College Faculty of Technology Department of Electrical Engineering, Information Technology and Cybernetics E-­‐mail: hans.p.halvorsen@hit.no Blog: http://home.hit.no/~hansha/ Room: B-­‐237a