NI CompactDAQ FAQs

This document contains a growing list of frequently asked questions about NI CompactDAQ and their answers.

Q: I have other USB devices, like my mouse and keyboard, that sometimes don't respond to the PC or wake up with my laptop. Is USB really a reliable bus for data acquisition?

Absolutely. Though reliability is not a key concern for some peripherals such as joysticks or keyboards, NI CompactDAQ was designed for high-performance data acquisition and operates properly if connected to a compliant USB port and powered within the specified range. There are several NI technologies at work to make NI CompactDAQ the high-quality data acquisition platform it is. Read Three Technologies that Drive USB Performance to learn more about this topic.

Q: Where can I get technical specifications for the NI CompactDAQ carrier and modules?

You can find NI CompactDAQ carrier and module technical information in the products’ user manuals, which are linked from the model page of each product. In addition to the model pages, you can find all National Instruments manuals online at ni.com/manuals.

Q: How do I configure and order an NI CompactDAQ system?

With the NI CompactDAQ Advisor, NI CompactDAQ is as easy to configure as it is to use. The advisor takes you step by step through your module selection, making sure your choices do not exceed the limits of the chassis. The NI CompactDAQ chassis includes an AC power supply and USB cable so your system is complete out of the box.

Q: Which applications can NI CompactDAQ handle?

NI CompactDAQ is a general-purpose data acquisition and control system that you can implement in a wide range of applications. It uses open software to run built-in data-logging programs for simple applications or to develop custom acquisition, analysis, control, and display programs for more demanding applications. NI CompactDAQ hardware and software are simple to use for quick benchtop measurements, small enough to take in the field with a laptop, and powerful enough to handle production line testing and light ATE. Customers are using NI CompactDAQ for applications ranging from in-vehicle test to environmental data logging to portable vibration monitoring.

Q: How do I use NI CompactDAQ for data logging?

NI CompactDAQ provides the acquisition and storage capabilities of traditional PC-based data loggers as well as a way to customize your data logger with modular I/O and powerful software options.

To use NI CompactDAQ for data logging, first customize your NI CompactDAQ system with I/O modules to meet your channel count and measurement type requirements. You may find it helpful to use the online NI CompactDAQ Advisor when configuring your system.

Next, select the software package that best meets your needs from the three levels of data-logging software offered with NI CompactDAQ.

• LabVIEW SignalExpress LE – FREE, interactive data-logging software that is shipped with each NI CompactDAQ system
• LabVIEW SignalExpress – full-featured, interactive data-logging software
• LabVIEW – complete, graphical development environment for creating custom data-logging applications

Q: Does the CAN module for CompactRIO work in NI CompactDAQ?

No. NI CompactDAQ does not support the CAN module, but National Instruments does have a solution to synchronize NI CompactDAQ with one of several NI CAN interfaces, including the PCMCIA CAN card. See the application note below for more information on this system setup.

Synchronizing NI CompactDAQ and CAN Measurements for In-Vehicle Data Logging


Q: What are the capabilities and limitations of Hi-Speed USB?

Hi-Speed USB provides a plug-and-play interface for connecting NI CompactDAQ to either a desktop or a laptop computer. With a 480 Mb/s data rate, Hi-Speed USB offers sufficient bandwidth for an entire NI CompactDAQ chassis full of dynamic acquisition modules.

One of the primary advantages of USB for PC-based data acquisition is the ability to extend the system away from the PC itself. However, the USB specification limits the distance between port and device to 5 m. You can use up to five USB hubs to extend the device beyond the 5 m cable limit. Several third-party vendors offer commercially available USB bus extenders to increase this distance to up to 2 km through various forms of connectivity such as fiber, copper wire, and even wireless.

Q: Which software is required to use NI CompactDAQ?

The only software you need is NI-DAQmx driver software for Windows, which is shipped with each NI CompactDAQ system. NI-DAQmx offers application programming interfaces (APIs) for development with LabVIEW, C/C++, Visual Basic 6.0, and Visual Studio .NET programming languages.

In addition to NI-DAQmx, National Instruments ships free measurement services software for configuring your system, testing your system, and completing basic data-logging tasks.

• Measurement & Automation Explorer (MAX) – software to save time configuring, testing, and calibrating your NI CompactDAQ system
• LabVIEW SignalExpress LE – FREE data-logging software for acquiring, viewing, and logging data from any NI-DAQmx device

National Instruments also offers the following software options, each of which is designed for optimized integration with NI-DAQmx and NI CompactDAQ.

• LabVIEW SignalExpress – full-featured, interactive data-logging software
• LabVIEW – graphical development environment for data acquisition, analysis, and presentation
• LabWindows™/CVI – ANSI C application development environment for data acquisition
• Measurement Studio – add-on development tools for Visual Studio .NET, Visual Basic, and Visual C++

Q: Does NI CompactDAQ come with a warranty?

The quality of NI CompactDAQ is ensured by a one-year warranty. Should the device fail due to a manufacturing defect within one year of purchase, you can return it to National Instruments for repair/replacement at no charge.


Q: How do I get technical support for NI CompactDAQ?

Visit ni.com/compactdaq for resources to aid in assembly and startup. For assistance and troubleshooting, visit ni.com/support. NI applications engineers can assist you through Web forums and e-mail or by phone.

Q: Am I guaranteed to achieve the acquisition rates that are specified?

All rates specified are for National Instruments C Series modules and the NI CompactDAQ chassis. These rates do not take into account program architecture or PC processing speed. Using computers with older processors or a non-Hi-Speed USB port limits your ability to use NI CompactDAQ to its design specifications. Buffer overflow errors are a common indication that the data acquisition hardware is supplying data at a rate faster than the PC can process it. The NI CompactDAQ Advisor features a tool that calculates the exact hardware operation rates when you use different modules and channels. Calculate your system performance at http://ohm.ni.com/advisors/compactdaq.

Q: What are the benefits of NI CompactDAQ for academic settings?

Specially configured NI CompactDAQ bundles offer a portable platform that helps users acquire accurate data quickly from a variety of sensors, whether in a hands-on teaching environment or research lab. Packaged with NI LabVIEW software, the academic NI CompactDAQ bundles are low-cost, flexible, ready-to-use measurement solutions. Visit ni.com/academic/measurements for more details on NI CompactDAQ and other academic product bundles.

Q: Some of the “new” modules have the same model number as modules that have been shipping for the National Instruments CompactRIO platform for some time now. Are these the same?

Yes. Some of these modules that have sold for the NI CompactRIO platform are now compatible with the NI CompactDAQ platform. If you already have one of these CompactRIO modules, you can use it in an NI cDAQ-9172 chassis even though it may have a “cRIO-9xxx” model number on it. Just make sure you download the latest version of NI-DAQmx driver software, Version 8.5, which is compatible with these new modules. The DAQmx readme.txt file lists supported NI CompactDAQ modules.

Q: Do all C Series modules work in both the NI CompactDAQ and CompactRIO platforms?

No. There are still some modules that work with CompactRIO but not NI CompactDAQ. Please see the NI CompactDAQ Advisor or home page (ni.com/compactdaq) to check for compatibility.

Q: Some of the C Series modules have their own single module carrier (NI USB-9162). Where can I see a complete list of the modules that work with the USB single module carrier?

NI is constantly updating C Series module support in the USB-9162 single module carrier. To learn which modules work with the single module carrier, see the readme.txt file for the NI-DAQmx driver. Search for the latest NI-DAQmx driver at http://joule.ni.com/nidu/cds/fn/p/lang/en.

Q: Can NI CompactDAQ read counter/timer signals or measure a quad encoder?

Yes. The NI CompactDAQ chassis contains two 32-bit counter/timer chips that perform both input and output operations. Access the source, gate, and count lines by installing a correlated digital I/O module (hardware-timed like the NI 9401) into slot 5 or 6 of the chassis. Once you have inserted the module, you can configure counter/timer tasks through the driver.

Q: Can I run more than one NI CompactDAQ chassis off of a hub with no decrease in performance?

In most cases, yes. USB is a shared-bandwidth bus meaning the 60 MB/s throughput is used by all devices that are connected to the same root hub. The number of modules and the rate of acquisition dictate how much bandwidth NI CompactDAQ uses, but internal NI benchmarks show that two chassis can acquire analog input data at maximum rate on many newer model computers. If you have questions about these systems, please contact us so we can help you spec out your system and share some of our internal test data.

Q: What is NI CompactDAQ made of? It looks like plastic in the images.

NI CompactDAQ, which is made of metal (A380), is more than rugged enough to survive the rigors of field, track, or even some industrial test use. See the NI CompactDAQ Video Demonstrations page for a drop test of the NI CompactDAQ system. http://www.ni.com/dataacquisition/compactdaq/videos.htm

Q: How do I synchronize two chassis together for higher-channel systems?

Each chassis has an internal timing engine, the NI-STC 2 chip. You can access the pins to this chip by placing a correlated digital I/O module (hardware-timed like the NI 9401) into slots 5 or 6 of the chassis. Using the digital module and the NI-STC 2 of each chassis to be synchronized, you can route the sample clock from one chassis into the connected chassis. This requires two chassis and two of the digital modules installed in slot 5 or 6 of each chassis. See the tutorial at http://zone.ni.com/devzone/cda/tut/p/id/5376 for more information.

Q: How long can a USB cable be?

USB specifications dictate 5 m, but there are some companies that make USB extenders and some off-the-shelf passive USB repeaters that can extend the 5 m limit. The 5 m is a single-cable limit, and you can use up to five hubs to extend the reach of the USB signal.

Q: What about wireless USB hubs?

USB wireless hubs are beginning to emerge in the marketplace and, just as with wired hubs, quality of design and construction can dramatically affect performance when it comes to high-quality data acquisition. National Instruments is currently testing wireless hubs for use with NI USB products. If you have an application that needs wireless transmission of a USB signal, please contact us so we can discuss your system requirements and make recommendations.

Q: Is there a GPIB interface for NI CompactDAQ?

No, GPIB throughput is far too slow. The data rates needed by some of the higher-speed applications are far too great for older bus technology. Hi-Speed USB provides the ease of use, bandwidth, and availability required for today’s data acquisition systems. However, with flexible software, such as LabVIEW, and the included NI-DAQmx driver, you can integrate NI CompactDAQ with GPIB instruments as well as other buses to form hybrid test systems based on PC technology.

Q: Where can I get more NI CompactDAQ information?

The main NI CompactDAQ home page at  ni.com/compactdaq features technical white papers such as the following:

NI CompactDAQ Under the Hood - Three Technologies that Drive USB Performance

NI Signal Streaming Makes USB More Powerful

 

 

The mark LabWindows is used under a license from Microsoft Corporation.

 

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