NI Data Acquisition Reduces Hidden Development Costs

According to a worldwide survey of engineers conducted by National Instruments, the total cost of developing a measurement system can be broken down into two parts:

• The price of measurement hardware and software
• Development costs

While the hardware and software price may appear obvious, development costs are often forgotten when calculating the total cost of the application. Virtual instrumentation combines software and modular hardware with off-the-shelf PC technologies to provide several solutions for minimizing those hidden costs that may appear in the development process. This white paper explains how, using the concept of virtual instrumentation, National Instruments data acquisition (DAQ) hardware and software can help reduce hidden costs in the development of an automated test or measurement application.

The Costs of a Measurement Application

A closer examination of the costs involved in measurement application development reveals that they can actually be divided into five distinct areas composed of hardware and software prices and several development time costs. To obtain the data in Figure 1, National Instruments conducted a survey of measurement experts worldwide asking about the costs of their most recent test or measurement system. On average, they cited the largest single cost as the price of the hardware and software. However, the cumulative time costs in the other areas make up the largest portion of the total application cost. (Note: Time costs are normalized to $100 per hour.)


The next five sections of this document explore each of these costs in detail and provide virtual instrumentation solutions for minimizing costs in each area.

Reducing System Specification Time Cost

Deciding which types of measurements to take and the types of analysis to perform takes time. Once you have set your measurement specifications, you must then determine exactly how to implement the measurement system. The time that it takes to perform these two steps equals the system specification time. In the NI survey, customers reported that this step consumed as much as 1/3 of the total application cost. However, the average customer spent about 12 percent of their total cost on system specification.

To further shorten this time, National Instruments has produced several resources, available online, over the phone, and in person. Product advisors, available online at ni.com/advisor, step you through the process of specifying a measurement system. They ask for information about sensor or signal types, sampling rate, number of channels, and other parameters, then recommend a hardware and software solution to match each user’s unique needs.

Additional third-party advisors, also available on ni.com, recommend complementary products to NI measurement hardware and software, such as sensors, stages for motion control applications, and rugged computers for taking measurements in harsh environments. By compiling information on all of the hardware products needed for common measurement systems into one location, these advisors help you find products you need more quickly. As a result, you can begin building your system more quickly, instead of spending time researching vendors’ websites for components.

National Instruments also employs technical representatives over the phone and in offices all over the globe to assist customers with specifying measurement systems. They have been trained to consult with customers on their unique application needs, and can help recommend the best system. By using the knowledge and experience available from these technical representatives, customers can shorten the time it takes to define a measurement system.

Lowering Hardware and Software Prices

The price of measurement hardware and software is undoubtedly the most visible cost of a DAQ system. Many people attempt to save money in this area without considering the effect on total development cost. By looking at Figure 1, you can see that the price of hardware and software, on average, makes up about 36 percent of the total application cost. However, the time and money spent on the development process make up the majority of the total application cost.

Virtual instrumentation lowers not only time costs, but it also helps to minimize hardware and software costs. M Series data acquisition devices, released in August 2004, set the standard for functionality and performance at a low price with price per I/O channel as low as $6.65. This was achieved by using 2 primary principles of virtual instrumentation:

1. Make use of off-the-shelf technologies where possible – Rather than implement a calibration routine similar to that of the E Series devices that used expensive CalDACs (calibration digital-to-analog converters), designers developed an patent-pending algorithm known as NI-MCal to achieve more accurate results with less-expensive, off-the-shelf CalPWM (calibration pulse-width modulation) parts. This is just one new feature that helped to keep prices low on M Series DAQ devices.
2. Combine software and hardware to achieve a better solution – The NI-MCal algorithm also relies heavily on software to achieve not only less expensive and more accurate, but also faster results. The calibration routine actually executes four times faster than the E Series calibration routine because much of it is implemented in software rather than hardware. Faster calibration execution can translate into significant time savings when it is executed before each run of a program, as many customers require.

As the worldwide market leader in data acquisition, National Instruments can also take advantage of economies of scale in the manufacturing process. NI has manufacturing facilities around the world and consistently strives to drive costs out of its manufacturing process. In 2002, NI released the PCI-6013 and PCI-6014 (B Series) multifunction DAQ boards that marked new low prices for 16-bit DAQ technology. In 2004 and into 2005, NI released manylow-cost USB DAQ devices and added more functionality to M Series devices without raising prices. By combining manufacturing efficiencies with industry trends, National Instruments promises to continue its industry-leading effort to keep measurement hardware costs low in future years.

See Also:
M Series Data Acquisition Devices
USB Data Acquisition Devices

Minimizing Setup and Configuration Time Costs

After you have specified and purchased measurement hardware, the real task of developing your application begins. However, you must first install the hardware and software, configure any necessary settings, and ensure that all pieces of the system function properly. This setup and configuration stage also includes any necessary fixturing, such as sensor connection, wiring, and any preparation of the unit under test. Figure 1 shows that this step typically consumes about 14 percent of the overall application cost, although several customers reported that this step consumed as much as 60 percent of their total cost. Therefore, saving time in setup and configuration can result in a large reduction in total application cost. Virtual instrumentation again delivers this cost reduction with a combination of off-the-shelf technology and intelligently designed software.

For example, many National Instruments DAQ devices make use of the latest computer bus technologies such as USB, FireWire, and PCMCIA to eliminate the need to open or even shut down the computer to install them. Like a plug and-play USB keyboard or mouse, plugging in one of these DAQ devices automatically prompts the operating system to automatically detect and install the device. In addition, high-performance NI-DAQmx driver software automatically detects PCI, PXI, USB, PCMCIA, and FireWire DAQ devices upon installation. As a result, it saves installation time. Large companies and university departments often share hardware among several departments. Fast setup time benefits these applications in particular, since the hardware frequently moves from one department to another.

NI-DAQmx includes configuration software that can also contribute time savings in setup and configuration. NI Measurement & Automation Explorer (MAX) automatically detects DAQ, GPIB, FieldPoint, PXI, and VXI devices so you can interactively configure them in one place. Integrated diagnostic tests ensure that devices function properly, and test panels provide a quick way check the signals on each channel of your DAQ device before you begin programming.

To further simplify installation and connectivity, NI was involved with the development of the IEEE 1451.4 standard for transducer electronic data sheets (TEDS). Essentially, TEDS is a small memory chip integrated into a sensor. It provides sensor information digitally to the computer to tell it how to convert (or scale) the sensor voltage or current data into the proper engineering units, such as °C or kilograms. This technology, known as Sensors Plug&Play, promises a major time saving in configuration, particularly for high-channel-count sensor applications. For legacy sensors that do not contain TEDS data, NI provides a database of Virtual TEDS, which contains downloadable TEDS files. As a result, you can reap productivity benefits of TEDS even without sensors equipped with the capability.

See Also:
NI-DAQmx Driver Software
Learn About New USB Data Acquisition Products
Sensors Plug&Play Resources

Decreasing Application Development Time Costs

Developing the measurement application code typically consumes about 25 percent, but can sometimes be as high as 50 percent, of the overall measurement application cost. Time-saving application development tools can often greatly reduce costs in this stage. To help you begin taking measurements faster, National Instruments now offers several ready-to-run measurement programs available to download from ni.com. These programs require only that the LabVIEW Run-Time Engine be installed, and you can start taking basic measurements immediately with your new DAQ hardware. If you do not have hardware yet, they also provide a simulation interface. In addition, some USB DAQ devices now include a ready-to-run data logger in their accompanying software.

Over the past several years, National Instruments DAQ software and its tight integration with the NI LabVIEW development environment have delivered results for numerous customers in applications ranging from simple to sophisticated. One of those customers, Marcel Auboiroux from MVI Technologies, describes the benefits, "Programming with LabVIEW has resulted in shorter development times, directly impacting our ability to offer final products at a more competitive price."

NI-DAQmx driver software is one tool that saves significant time in the software development stage. It includes DAQ Assistant, which you use to interactively configure and run your data acquisition task, including timing, triggering, and sensor scaling, in any NI development environment. It takes only four steps with the DAQ Assistant menu-driven interface:

1. Choose the appropriate DAQ task/sensor type (for example, thermocouple input or digital output).
2. Associate one or more physical channels of the DAQ system with the task and enter voltage or sensor scaling information so the data will display in the proper units.
3. Select timing, triggering, and sampling information (that is, continuous input, 1 kS/s sampling rate, operation started by a digital trigger).
4. Run the task.

Developing a basic measurement application takes minutes using DAQ Assistant (Figure 5), which eliminates the need to program most DAQ functions. In addition, you can quickly modify the parameters in DAQ Assistant if necessary, without having to program at all. DAQ Assistant also integrates seamlessly with LabVIEW analysis functions such as spectral measurements and histograms. Data acquired by DAQ Assistant can be input directly into these analysis functions without any manipulation or additional programming.


For more complex DAQ applications, you can use DAQ Assistant to automatically generate modifiable NI-DAQmx code for LabVIEW, C, or Measurement Studio for Visual Studio. NET with a few mouse clicks. By using this code as a starting point, you begin with code that works. Automatic code generation can save an enormous amount of time that you might normally spend consulting manuals and the trial-and-error steps of learning the proper method for programming the DAQ device. As a result, you can focus on coding only the unique parts of your application.

NI-DAQmx also includes a technology known as virtual channels. A virtual channel associates a physical channel on a DAQ system with voltage, sensor, or custom scaling information. An interactive menu provides the interface for inputting all of the information. Because virtual channels can be used in any LabVIEW or any other NI development environment, they eliminate the need to perform any scaling programmatically. Compare the two LabVIEW diagrams in Figure 7 below. Without virtual channels, you spend a large amount of development time just converting thermocouple voltages into °C. Conversely, virtual channels give you the freedom to focus on other areas of the measurement application.

It is common for application development to begin without possession of the measurement or control hardware. However, this can be problematic since most driver software and the associated API will not execute properly or return device-specific errors without the hardware installed in the development system. To get around this, software developers create simulation subroutines that temporarily replace the measurement and control code within the application. This method makes it difficult to get a start on the measurement or control portion of the application development and it makes it virtually impossible to debug the code. NI-DAQmx driver software offers simulated devices for all supported measurement and control hardware. This feature enables you to begin code development on your schedule and debug the code before any hardware arrives or is installed.

Another way to achieve faster development time is to start with an example program, rather than a blank screen. NI installs numerous example programs with the NI-DAQmx driver software and provides more than 3000 example programs free of charge in a database searchable from ni.com/examples or from the LabVIEW or LabWindows/CVI development environment. Some of these examples have a general focus, such as a program that illustrates how to acquire analog data with a digital trigger. Others highlight a specific application, such as a program showing the acquisition and analysis of dynamometer data. With such a large database of examples that address every aspect of application development, you may find an example that very closely fits your application requirements. According to Timothy R. Brooks of B&B Technologies, Inc, "The complete package of drivers and examples shipped with the NI products saved weeks of development and testing time."

See Also:
NI-DAQmx Simulated Devices
Download Ready-to-Run Measurements

Lowering System Validation and Hardware Calibration Time Costs

Virtual instrumentation relies heavily on software to provide productivity gains and flexibility. In the validation and calibration stage of measurement application development, you can find examples where this proves especially useful. For one, National Instruments DAQ devices can be self-calibrated entirely in software. You do not need to manually adjust potentiometers or remove hardware from the computer to calibrate a device. Instead, call a single function either programmatically or interactively from MAX (see Figure 7), and the software handles the calibration routine. The new NI-MCal routine executes in seconds and provides up to a 5X improvement in accuracy.

In the past, National Instruments E Series devices recommended that external calibration be performed annually. With the new calibration improvements made possible by NI-MCal, the external calibration interval has now been extended to two years. This not only saves you money, but also decreases the amount of downtime you experience due to external calibration.

Another accuracy advantage that NI-DAQmx driver software offers is integrated end-to-end signal/sensor calibration. If you have a precision source that spans the range of your sensor/signal, the channel calibration wizard enables you to do a multi-point DC calibration which is applied to all subsequent readings on that input. The channel calibration wizard also stores the name of the calibrator, expiration date, and any notes that the operator has at the time of calibration (see Figure 8). For thermocouples and other sensitive sensors, accuracy improvements of over 20% are easily achieved. This capability can be implemented interactively with the DAQ Assistant or can be implemented programatically using the NI-DAQmx application programming interface.

Thoroughly debugging and testing a measurement application can also consume a large amount of time without proper error reporting. NI-DAQmx software takes a new approach to error reporting that suggests causes of the problem and a possible solution, rather than reporting a cryptic error code that references a print manual. Compare the NI-DAQmx error reports below with an error report from another vendor. The NI-DAQmx error notification explains the property that the user requested, and then lists the valid properties. The "Other" error notification simply returns a number with no explanation of the problem or suggestions for resolving it.

Summary

Data gathered from a user survey revealed that the total measurement application cost includes not only the price of hardware and software but also hidden time costs. However, DAQ software designed to improve productivity, online tools to help you make decisions and get started quickly, and accurate, reliable hardware at an affordable price help minimize these costs. As Marcus Anderson of Roush Industries explains, "We realized significant development time savings by choosing to create the system based on National Instruments hardware and software in a PC platform." In turn, cost savings such as these help you get products to market faster and at a more competitive price. To better quantify this, examine the chart below. It shows a sample application in which the hardware and software costs $50,000 and time costs in the other areas adhere to the ratios from Figure 1. Assuming that virtual instrumentation can save you at least 10 percent and as much as 40 percent of the cost in each stage of the application, you can see the total saving in dollars that will result.

 

Related Links:
Products & Services: Data Acquisition (DAQ) Hardware
Products & Services: Data Acquisition (DAQ) Software

Reader Comments | Submit a comment »

No CVI sample ?
It would make sense to add one or two CVI sample code. This would show the programming model is really the same whatever is the ADE. In addition, for what I know DAQmx solves many issues CVI users had doing DAQ with LabWindows and so help to reduce cost of C based applications as well (start coding faster, use boards with more efficiency etc.) Finally, it could be pointed out that since programming model is the same whatever is the kind of board or operation, DAQmx helps CVI programmers to cut cost(this was not the case with previous version of NIDAQ since specific functions needed to be used depending on the board or operation (acquire, generate etc.) My two cents, regards.
- Feb 24, 2004