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NI-DAQmx and Traditional NI-DAQ Frequently Asked Questions

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Answered in this document on the NI-DAQmx and Traditional NI-DAQ to some frequently asked questions. In accordance with the logic of all the problems are divided into the following four categories:


NI-DAQmx Description

NI-DAQmx to introduce the concept of


From the traditional NI-DAQ to NI-DAQmx upgrade

NI-DAQmx Description

Q: Why are software applications for data collection so important?

A: The function of flexible and powerful software is the core of virtual instrument system.

Let us carefully look at the composition of virtual instrument software. First of all, most people think of is the application layer, is the main development environment. It includes, such as LabVIEW, LabWindows / CVI (ANSIC) and MeasurementStudio (VisualStudio programming language) such as software. Test the implementation of the application layer combines the functions of the development layer. The next layer is usually very easy to be ignored, but it is for the efficiency of software development is essential. Measurement and control services layer includes communication with the hardware drivers. Measurement and control services must be able to access and play the hardware functionality and performance, they must also be driven with all other solutions and has become part of the many modular I / O work.

Figure 1. Virtual Instrument Software

NI-DAQmx and Traditional NI-DAQ Frequently Asked Questions

Q: What is the measurement services software?

A: The measurement services software can be viewed as I / O driver software layer, however, it is not just a driver.

Measurement service is rapid application development in one of the most important part. The software provides a virtual instrument software and hardware connectivity between the measurement and control for. Intuitive Application Programming interface (API), instrument drivers, configuration tools, rapid I / O assistants, and other included in the purchase of hardware in the NI software is that it features. NI measurement and control services software with NI hardware and NI application development environment (ADE) to optimize the combination.

Table 1.NI-DAQmx driver contains a high-performance add-on software and systems development to improve the efficiency of

NI-DAQmx and Traditional NI-DAQ Frequently Asked Questions

NI Measurement & Automation Explorer (MAX) and DAQAssistant (DAQ Assistant) is the NI-DAQmx measurement services software (most of NI data acquisition devices are attached to the software) embody the infinite value of its two examples. In addition, NI also M series and many other USBDAQ equipment and equipment on the attached data recording software free of charge.

Such as the MAX configuration tool such as the characteristics contained in the configuration and can be used to test I / O, and storage calibration, calibration and channel alias information. These tools for a shorter time to complete the first measurement, the maintenance of test systems and solutions to test system failure is very important.

I / OAssistant (I / O assistant) is an interactive tool to quickly create measurement applications. DAQ Assistant is one such I / O assistants, as shown in Figure 2. It provides a panel, you can easily configure commonly used in the above parameters of the DAQ, and without any programming. You can use any NIADE generated by its DAQ task. Helper easy-to-use and powerful combination of programming environment provides a rapid development and wide application to meet the needs.

Figure 2.NI-DAQmx offers the DAQ Assistant simplifies the task of creating DAQ

NI-DAQmx and Traditional NI-DAQ Frequently Asked Questions

Q: Why NI introduced NI-DAQmx? Why not continue to develop the traditional NI-DAQ?

A: NI in the 20th century, 90's the first time the traditional NI-DAQ driver. Traditional NI-DAQ devices by providing an extension of the various functions of the DAQ library has many improvements including double buffering acquisition of specific types of sensors to provide built-in scale, such as thermocouples and strain gauges, signal conditioning, as well as a single and with a variety of devices and operating system (OS) of the library work.

In the late 90's, NI-DAQ team aware API to maintain compatibility with previous versions of this requirement has increased the traditional NI-DAQ to add new features and equipment more difficult. In addition, the development of long-term process, the traditional NI-DAQ generated a lot of the API need to be addressed. NI-DAQ developers intuitively difficult to extend the API and are difficult to optimize the growing range of customer applications. NI therefore that a new API design and architecture of NI-DAQ can help developers more easily add new features and new equipment, solve many of the existing drive, and can optimize performance at the same time.

NI-DAQmx some grand goal of the project include:

1. DAQAPI to more easily add new features. Traditional NI-DAQAPI many functions have a large number of parameters and there is no effective way to add new parameters. In contrast, NI-DAQmxAPI through a rich level of the attribute attribute-based approach. Easy to extend this approach. Typically, to add a new features and add a new attribute as easily.

2. More easily add new equipment. If we do not change the existing functions, NI will be difficult to Traditional NI-DAQ to add more equipment, and changes often lead to a number of loopholes. Find and solve the loopholes in the accident to spend too much time to release a version of each. In contrast, NI-DAQmx to use as a component of the plug-in design, making it easier to add new equipment.

3. More effective multi-threaded data collection. Traditional NI-DAQ is the first multi-threaded functions do not have older versions of the operating system designed. In order to secure multi-threaded operating system to run, the traditional NI-DAQ will limit access to the operation of each thread. For those who need to complete the tasks of two or more DAQ application are concerned, this raises the question of restrictions on the two tasks can not access the drive at the same time. NI-DAQmx using multi-threaded design to solve the problem, so many threads can access the drive at the same time.

4. To enhance the performance of data acquisition, in particular the performance of a single point. Some use the traditional NI-DAQ application software have experienced poor performance of a single point from time to time, as they continue to implement the main loop costly operation, such as the authentication scheme (test), to retain resources (retained) and the programming of the hardware ( Operation). Traditional NI-DAQ is not the time for implementation of the inspection, retention and implementation of applications to operate to give adequate control, so users can not rewrite these applications to run faster. NI-DAQmx using a state model based on the definition of the design to improve performance. NI-DAQmx to provide users with a high-level API functions, such as inspection, retention and implementation. Therefore, when users in the implementation of these costly operations have more control.

5. To improve driver performance and reliability. NI-DAQmx designed into a world-class data collection performance and stability. NI-DAQmx development since the beginning of each user to add a new characteristic or a change of driver, a strict and complete functionality and performance automated test package will test whether this change was introduced loopholes. This test applies to all kinds of package of equipment, sensors and operating system configuration in the common and uncommon drive to be tested. Unusual or exception-driven applications is very important for the overall reliability. NI-DAQmx designed to deal with unusual situations, such as the DAQ task suspension, termination and accidents watchdog timer device to delete (for example, pull out the USB from your computer equipment).

6. More easily carry out data collection. However, this approach has caused some problems, because once the user applications need to add more advanced features, they had to use more advanced API to rewrite applications. NI-DAQmx makes the following ways to develop applications more easily:

Such as the DAQ Assistant configuration tool. Using DAQ Assistant, the user can choose the graphics they want to measure the type of configuration in order to preserve for later use, and generate code to include in the application.

NI-DAQmx advanced routing features. These features simplify the DAQ trigger and synchronization equipment.

In NI-DAQmx and describe errors in the report. This feature helps users to pinpoint the causes of errors and recommend solutions. NI-DAQmx users that in the error reporting feature allows high-level DAQ application debugging easier.

LabVIEW7 started from the easy-to-use features. LabVIEW7 the introduction of the new features, especially the application of the NI-DAQmx of new features, including the creation of ExpressVI and the ability of polymorphic VI. The use of ExpressVI, the user can use a simple dialog box to configure a complex to replace the vast majority of DAQ. The use of polymorphic VI, users can more easily find properties. Due to the characteristics of these two aspects, the user can use less time to develop applications.

Figure 3. Polymorphic VI to simplify the NI-DAQmxAPI

NI-DAQmx and Traditional NI-DAQ Frequently Asked Questions

Q: NI-DAQmx hardware support for what? What hardware do not support?

A: As the latest NI measurement services software, NI-DAQmx supports the latest hardware NIDAQ, including the M Series Plug-in DAQ devices, USBDAQ some of the latest equipment, as well as hundreds of the traditional NI-DAQ supported DAQ devices.

Although a number of NI-DAQmx support NIDAQ the latest hardware, NI-DAQmx does not support all of the equipment NIDAQ. For example, the traditional DAQ devices, such as the use of ISA Bus (for desktop computer) equipment, they are only by the traditional NI-DAQ support.

For would like to know the current NI-DAQmx supported devices list, please visit ni.com / dataacquisition / software and click DeviceSupport (supported by the device), or see included in the NI-DAQmx in NI-DAQmxReadme document.

Q: Why do some DAQ device only by NI-DAQmx support?

A: such as the M Series DAQ devices, such as up-to-date, the best DAQ hardware. M Series devices are the market's first 18 plug-in DAQ devices, the first has a maximum data throughput of up to six DMA channels DAQ plug-in equipment, with innovative equipment and calibration. These devices only by NI-DAQmx support from the traditional NI-DAQ support.

NIDAQ new equipment in future will also be limited only by NI-DAQmx support, while those who are in support of the traditional NI-DAQ. NI engineers NI-DAQmx is committed to efficiency and performance, rather than the traditional use of resources to the development of driver software.

Q: Can I NI-DAQmx programming language with which to share?

A: You can use NI-DAQmx will be a variety of programming languages, including:



MicrosoftVisualC + + Class Library (NIMeasurementStudio7 or later)

MicrosoftVisualC + +

MicrosoftC #. NET


MicrosoftVisualBasic (Beta version)

For more information about using NI-DAQmx programming languages and text-based information, please visit the NI-DAQ programming language for Text language and NI-DAQReadme document.

Q: I can be with the NI-DAQmx application development environment which combination?

A: NI-DAQmx with many of the most popular work ADE. Once installed the NI-DAQmx, you can choose to install on a variety of ADE support, including:

NILabVIEW7 or higher

NILabVIEWReal-Time7.1 or higher

NILabWindows/CVI7 or higher

. NET languages

NIMeasurementStudio, support for VisualC + +. NET (need MeasurementStudio7 or higher)

MicrosoftVisualC support

In order to install the support for these ADE, please install the NI-DAQmx in the selection of appropriate support. When you first install the NI-DAQmx, the characteristics of the trees in the NI-DAQmx options will be carried out, and then, select the API you want to use to install the appropriate support.

Figure 4.NI-DAQmx provides API for a variety of different ADE

NI-DAQmx and Traditional NI-DAQ Frequently Asked Questions

If you have already installed NI-DAQmx and want to change your choice, run the Add / Remove Programs. NI software to choose the entrance and then click Change. Then, the machine has been installed on your NI software list, select NI-DAQmx. Click Modify to start the NI-DAQmx installer, where you can specify the API support options.

Q: NI-DAQmx is applicable to Linux? MacOSX operating system?

A: NI-DAQmx only applies to those who MicrosoftWindows developing applications and user applications. NI currently has no plans to expand the NI-DAQmx to Linux and MACOSX. However, recently these platforms in the field of scientific and engineering computing applications increase, in order to meet these needs, NI has developed a NI-DAQmxBASE.

NI-DAQmxBASE to NI-DAQmx functionality to a subset of Windows, Linux, MacOSX and PocketPC operating system, and supports most of the most popular NIDAQ equipment, including new low-cost products USBDAQ.

Please visit ni.com / linux and ni.com / mac for Linux and MacOSX is the latest NI products.

Q: NI will continue the traditional NI-DAQ development of it?

A: NI has no plan to continue to develop the traditional NI-DAQ. However, in order to maintain the existing applications, NI will continue to provide the traditional NI-DAQ and to continue to provide its technical support.

Q: NI-DAQmx and NI-DAQmxBase What's the difference?

A: The comparison of these software tools is the best way to ni.com / dataacquisition / software driver to use comparison chart. Mentioned here are some differences.

Although the NI-DAQmx and NI-DAQmxBASE with a similar API, but these two have a completely different API architecture. NI-DAQmxBase using NI tools - NI Measurement Hardware Driver Development Kit (DDK) written in the register-level programming tools to customize the way of the development drive. One of the advantages of this approach is the NI-DAQmxBase is an open source code. This allows you to open a sub-VI (subVI), and observed in LabVIEW / Edit register access, and add or modify functionality.

NI-DAQmxBASE not in the NI-DAQmx software contains a number of characteristics. NI-DAQmx only have a number of features include:

DAQ Assistant

Task for the properties of high-level DAQ nodes

Multi-threaded I / O performance

Q: Under what circumstances should not choose to use NI-DAQmx to develop it?

A: Although the NI encourage you to NI-DAQmx will make full use of the advantages to your application, but in some cases the use of NI-DAQmx is not ideal.

If one of the following circumstances exist, please install and use the traditional NI-DAQ:

Do you have a NI-DAQmx does not support the equipment, such as an AT (for the ISA interface) E Series multifunction DAQ card.

You are using LabVIEW, LabWindows / CVI or MeasurementStudio before version 7.0.

You are using VisualBasic6.

NI-DAQ6.9.x you want to upgrade and there you do not want to and connected to NI-DAQmx applications.

If one of the following circumstances exist, please install and use NI-DAQmxBase:

You are used in the development of Linux, MacOSX or PocketPC based applications.


You have an NI-DAQmxBase only by USBDAQ support equipment.

If one of the following circumstances exist, please use the installation and use MeasurementHardwareDDK:

You are using a register-level programming to develop a custom driver.

For want more help to decide what kind of driver software for you, use ni.com / dataacquisition / software on the device driver software to support the table and compare plans, as well as documents NI-DAQReadme.

Q: How do I get NI-DAQmx?

A: NI to buy from the NI-DAQmx support for hardware products supported by the case, which will be accompanied by a NI-DAQ CD-ROM, which contains the latest version of NI-DAQmx.

You can access through the browser ni.com / china / daq free download the latest version of NI-DAQmx software.

NI-DAQmx to introduce the concept of

Q: What is the DAQ Assistant?

Answer: DAQ Assistant is a wizard-based steps, which can be programmed so that you do not need to configure the data acquisition tasks, virtual channels, as well as the realization of zoom. You can launch NI application software DAQ assistant, such as LabVIEW, LabWindows / CVI, MeasurementStudio, VILogger or MAX.

Figure 5.DAQ assistant ADE support all NI

NI-DAQmx and Traditional NI-DAQ Frequently Asked Questions

Note: You must use LabVIEW, LabWindows / CVI and the MeasurementStudio version 7.X or later, and 2.X versions VILogger to use the DAQ Assistant.

You can also use the DAQ Assistant to generate the NI-DAQmx code to run your tasks and the overall virtual channel, or transfer them to other systems.

Using DAQ Assistant, you can:

Create and edit tasks and virtual channels

Add a virtual channel to the task

To create and edit range

Test your configuration

Save your configuration

NI in your application code to generate your application in the use of

Observation of your sensor connection diagram

Q: Why should I use instead of using the DAQ Assistant NI-DAQmxAPI?

Answer: DAQ assistant built on NI-DAQmxAPI above, and can be used as a configuration tool and learning tool to speed up you in the new NI-DAQmxAPI on the learning speed.

After the configuration, LabVIEW's DAQ assistant ExpressVI contains all the necessary code to run the API to configure your task, but it is hidden in the block diagram of the procedure. If you would like to observe in your configuration or modify the API functions instead of using DAQ Assistant dialog box, DAQ Assistant also provides a code generation function, can be used in LabVIEW, LabWindows / CVI and MeasurementStudio applications.

Q: What is NI-DAQmx task?

A: NI-DAQmx task is to have the timing, trigger and other characteristics of one or more of a collection of virtual channels. Conceptually, a task represents a measurement you want to complete the task or signal generator. You can create and preserve the mission of the configuration information and the use of the application task.

Q: NI-DAQmx virtual channels in the local and global virtual channel What is the difference?

A: NI-DAQmx, you can configure virtual channels as part of the mandate and tasks, or separation. Founded in tasks within the virtual channel is the local virtual channel. Outside the definition of the mission is a global virtual channel virtual channel.

MAX you can or your application software to create a global virtual channel and then save them in the MAX. You can also arbitrary applications in the use of global virtual channel or add them to many different tasks. If you modify a global virtual channel, this change will affect all virtual channel quoted the overall task.

Q: When should I use a task rather than a global virtual channel?

A: When a task is with timing, triggering and other characteristics of one or more virtual channel when a collection.

A global virtual channel has been invoked only a physical channel, but does not include timing or trigger function. However, the overall virtual channel can be included and cited a number of tasks, while a task is an independent entity, it can not be contained or referenced in other tasks.

Q: Can I use a programmable NI-DAQmx virtual channel to preserve it?

A: The use of NI-DAQ7.4 or later, you can create and save programmable tasks, virtual channels and the overall range. This program will save the object appears in the MAX, you can in the DAQ Assistant and applications to use them.

Preserved programmable tasks, access and scale to simplify the system configuration and the application of a variety of occasions, and reduced the possibility of error and debug needs.

For more information about how to use this feature, as well as watch the routine, please visit http://ni.com/dataacquisition/nidaqmx..

Q: How do I import / export of equipment, tasks, channels and scaling configuration?

A: The use of MAN, you can export the configuration of your system or application as a backup to other machines.

Export Wizard can be used to copy configuration data from the system to a file. To start the Export Wizard, on the MAX Select File »Export

Q: What is the attribute node?

A: The attribute node is that you can use the LabVIEW structure, it can be used in applying to visit the properties of the object. NI-DAQmx to use these structures to deal with all of the NI-DAQmxAPI attribute support to provide complete programming control, and the formation of these attributes nodes of the basic functions of the API.

In addition to properties outside the nodes, NI-DAQmx also offers a set of NI-DAQmxVI, so you can use to write programs. These VI in the functional properties of the node with the use of equivalence, but is usually easier and more user-friendly. For example, the following two examples are functionally equivalent, however, the first example of using the NI-DAQmx, and another example of the use of NI-DAQmx property node.

NI-DAQmx and Traditional NI-DAQ Frequently Asked Questions

Figure 6. The use of NI-DAQmx property nodes to achieve high-level custom task

For most applications, NI-DAQmxVI provides the necessary functions. However, for more advanced applications, you may need to attribute node to get less use of the properties and characteristics of the driver.

Q: How should I filter the list of attribute nodes?

A: When you first open and view an attribute node, the attribute list of the shows may seem very hard. In order to more easily browse these lists, as shown by the following dialog window to use some filtering properties.

NI-DAQmx and Traditional NI-DAQ Frequently Asked Questions

To access the dialog box, right-click the node and click Properties to SelectFilter. ShowAllAttributes shows the NI-DAQmxAPI all supported attributes. ShowAttributesForConfiguredDevices shows all currently installed and configured on your system attributes support equipment. ShowAttributesForSelectedDevices choose to use it you need to show the attributes of the installed equipment.

In addition to filtering options, you can also see through the LabVIEW help a complete list of device properties. To find the list, click the menu bar of Help, and from the help window as shown in the choice of table VI, Function & How-ToHelp. And then navigate to the VIandFunctionReference »NIMeasurementsVIsandFunctions» DAQmx-DataAcquisitionVisandFunctions »AdditionalInformation» DeviceConsiderations »SupportedPropertiesbyDevice.

Q: What is NI-DAQmx simulation devices?

A: The use of NI-DAQmx7.4 version and an updated version, you can create NI-DAQmx simulation devices. You can choose any NI-DAQmx supported as a simulation equipment and equipment MAX add to your hardware configuration. This allows equipment to use through the application software.

NI-DAQmx and Traditional NI-DAQ Frequently Asked Questions

NI-DAQmx simulation devices are very useful, can be used to create and run the NI-DAQmx procedures, but without the existence of any physical hardware to test, such as DAQ Assistant or SignalExpress tools. NI-DAQmx simulation devices in the absence of real time to explore the physical hardware device performance is also very useful.

Test the use of NI-DAQmx task of simulation equipment, as they run on in the real equipment. If a property has been home to an invalid value, returning an error to the simulation equipment and equipment back to the real error is the same. All the tasks the resources needed for the NI-DAQmx simulation devices and save. RTSI lines, PXI trigger lines, DMA channels, counters, etc., as they like in the real device was counted and preserved.


Q: NI-DAQmx which provides improved performance?

A: applications in the user properties of the DAQ is that many factors, including sampling rate, bus speeds, drive performance, analysis, and other operations. In many applications, NI-DAQmx can improve application performance on traditional DAQ, as driven architecture improvements include the following:

1. Multi-threaded operation. Use NI-DAQmx, due to different in the implementation of NI-DAQmx tasks, the multiple threads can access the NI-DAQmx driver, so if you are using LabVIEW or c multi-threaded process, performance can be improved. Multiple threads to access the drive's ability to DAQ applications in addition to bottlenecks, and in some cases can greatly improve performance. Multi-threaded operation allows the implementation of multi-task and those who read or write more than one sample to improve the application performance is particularly evident.

2. For a lot of tedious tasks of data collection operations and better control. Use NI-DAQmx, you can better control the operation of the various drivers, such as configuration checking (inspection), preservation of resources (preservation) and on the hardware programming (the implementation), and past some of these operations will become a bottleneck in application development. Use NI-DAQmx, you can develop an outside circle of the main DAQ inspection, preservation, or the implementation of the application tasks, so drivers no longer need to repeatedly perform these operations.

3. Built-in hardware to operate a single point from time to time. Version of NI-DAQmx7.2 introduced from time to time on the need to implement a single point of hardware data acquisition applications built-in support. With traditional NI-DAQ, this new model has many built-in advantages, including better single-point tasks (the use of multi-channel) performance.

NI-DAQmx team has been working to improve the performance of NI-DAQmx.

Q: Why is NI-DAQmxCPU usage 100%?

A: Some users have noted that they deal with the DAQ so that CPU utilization reached 100%. Use NI-DAQmx7.3 version or earlier versions of the implementation of the application of a read or write call in, this could happen. Typically, excessive use of CPU to run other applications is not a problem, but for notebooks, NI-DAQmx will be caused by consumption of battery power and CPU fan start.

Since the NI-DAQmx7.3 version or earlier versions in a read or write operation will wait for the arrival of new data, so 100% of CPU utilization occurs. Waiting for the arrival of new data, if in a data read operation is still not available, NI-DAQmx7.3 version will turn to other treatment. If a deal with the need to use CPU, NI-DAQmx will be shared with the processing CPU. However, if no other tasks to deal with or need to use the CPU, NI-DAQmx to wait for the arrival of new data. If your computer is only the implementation of data collection, this solution provides a very good performance, in sharing with other applications when the CPU provides better performance. However, in the absence of side effects is to run other applications when the NI-DAQmx occupy 100% of CPU usage.

The best solution is to use the recently released NI-DAQmx, such as the NI-DAQmx7.4. NI-DAQmx7.4 changed the type to read and write the buffer to wait for the default mode of operation. When the time polling, NI-DAQmx in to read or write operations will be dormant until a short time (1ms). With the previous version of NI-DAQmx, this change in the majority of applications for virtually no impact on performance. However, other versions of NI-DAQmx7.4 read and write not only to improve and optimize performance to make up for possible losses. Applications to upgrade to NI-DAQmx7.4 performance can be improved not only can reduce the CPU utilization rate.

If you need to wait for data NI-DAQmx7.4 way more control, you can choose a different time or sleep mode time to wait for change or sell polling. Transfer mode to use with the NI-DAQmx7.3 cause similar behavior. Means the use of polling will cause the greatest throughput but at the same time to run other applications is not appropriate under the circumstances.

Q: single-point I / O performance has not improved?

Answer: Compared with traditional NI-DAQ (Legacy) compared, NI-DAQmx in almost all cases provide a better single-point I / O performance. However, in some cases, the traditional NI-DAQ (Legacy) provides a better performance.

It is worth mentioning that, NI-DAQmx for the following applications with better performance of a single point:

1. For the simulation and count the software from time to time to read and write access

2. That contains multi-channel software or hardware from time to time read or write

Traditional NI-DAQ has provided the following applications for better performance:

1. The use of digital channel read or write

2. For only one input and output hardware access applications from time to time a single point

Note: Traditional NI-DAQ hardware user may not be familiar with a single point from time to time. In particular, these applications use the hardware from time to time, the cache size to zero and each time a sample read or write.

Sometimes, the traditional NI-DAQ will be faster, because the NI-DAQmx than the traditional NI-DAQ provides more functionality. For example, you can port the line and NI-DAQmx digital channels to connect. Support multi-threaded and handle unusual circumstances, such as the accidental deletion of such equipment, which will add some additional expenditure.

Many DAQ applications need the absolute best performance, NI-DAQmx also been committed to the development team can improve the performance of the new features drive.

Q: state machine is how to help improve the performance of NI-DAQmx for?

A: NI-DAQmx task of tracking the status of the function stored in the data acquisition or generated before you can start the configuration of the operation needs to be done. Configuration operations, including inspection configuration (test), preservation of resources (preservation), as well as hardware programming (the implementation).

NI-DAQmx using the state machine to ensure the operation of costly tasks such as testing, resource conservation and hardware programming only if necessary. When in the main collection or signal generated outside the circle show the configuration operation, a DAQ application can benefit from improved performance. NI-DAQmx provides the display command, may cause a test to be performed, or the implementation of preservation. When a task showed that in the acquisition or generated outside the test cycle, preservation, or the beginning of the implementation, NI-DAQmx does not repeat them in each cycle of operation. On the whole, therefore, applications run faster.

For more information about the status of each NI-DAQmx information, please see the NI-DAQmx Help.

Q: What is to restrict the flow of the main factors disk performance?


A: The disk I / O bandwidth, CPU bandwidth and bus bandwidth.

Disk I / O bandwidth

IDE drives typically use the system was limited by the throughput of the disk.

Potential for improvements include adding a dedicated stream drive or controller. A dedicated drive to avoid the result of debris and operating system or other applications to access the disk and caused performance problems. High-speed drives and high-speed RAID controller to increase the disk I / O bandwidth.

Note: in the installation of drives and controllers before you check CPU bandwidth and bus bandwidth in order to prevent the increase in disk I / O beyond the fact that you can use the scope.

CPU bandwidth

For raw data, the processor bandwidth is usually only in high-speed RAID controller installed in the system performance. In these systems, CPU can affect how quickly you get the data and put it into the disk drive. Even use a dedicated RAID controller, CPU bandwidth is also part of the data was written into the disk consumption. For by scaling the data, the processor bandwidth constraints often.

Increase in the number of system and CPU speed of the CPU bandwidth of the system.

Even when the CPU utilization rate of less than 100%, the smallest of tasks and operations in parallel. Competition for scarce resources will be reduced flow disk performance.

Finally, the system of regulation for a particular flow code. For multi-CPU system, the implementation of a number of parallel code may increase the throughput of the system. (Note: a disk with a parallel disk I / O operation is usually reduced performance) to optimize the code to avoid memory copies and other waste of CPU bandwidth operation.

Bus bandwidth

With a typical single PCI / PXI bus will be desktop systems limit bus bandwidth. Standard PCI / PXI theoretical bandwidth of about 130MB / s. Real bus bandwidth according to the degree of competition and lower. Typically, in the same bus to run more devices at the same time reduce the bus bandwidth.

Note: a single NI6115DAQ can be 80MB / s data

Increase in the number of system bus is the only way to increase the bandwidth. For example, some high-end motherboards include two or more independent PCI bus. This will help you create a system, the system bus at an independent, there is a RAID controller and DAQ equipment. For these motherboards, the bridge-chip may limit the total of all connected bus throughput.

Q: NI-DAQmx to implement high-speed streaming to disk performance?

A: NI-DAQmx affect the flow properties of the main disk is that it uses the CPU at the same time mobile bandwidth and the scaling of the data acquisition equipment. Therefore, for those CPU bandwidth is a limiting factor of the system, NI-DAQmx efficient use of CPU it is very important.

Since the first time in order to reduce CPU usage when reading and writing began, NI-DAQmx experienced a number of optimization. For example, in the NI-DAQmx7.3 and version of NI-DAQmx7.4 between the analog input scaling performance benchmark from 8% to 60% growth. Not scale the performance of the analog input from the 12 percent benchmark increase to 40%. For those nervous system CPU bandwidth, the performance improvement directly into higher throughput of the flow plate.

NI-DAQmx to use a very simple form of compression. The end of the digital sampling was simple and will be discarded from the sample package into memory. NI-DAQmx does not use the other without loss or loss of compression algorithms such as LZE or JPEG.

In some cases, have been included due to sampling could not be used and hence there is no data loss. For example, a 12-bit resolution and sample size of 16-channel contains four non-use of spaces. You can be discarded without loss to 4 at the same time that disk space needed to decrease by 25%.

In addition, you can configure the NI-DAQmx discarded sampling in one or more bits does not matter. For example, you can configure a 24-bit resolution and sample size of 32 channels but only to return to the top 20. A total of 12 discarded, including non-use of the 8-bit, so that disk space required for the rate of decrease of the 37.5%.

From the traditional NI-DAQ upgrade

Q: Why should I upgrade the traditional NI-DAQ to NI-DAQmx?

A: There are many reasons to explain why the upgrade to NI-DAQmx. An important reason is that NI engineers committed to improving the NI-DAQmx rather than the traditional NI-DAQ (Legacy) the efficiency and performance. If you are using the latest measurement services software version, NI-DAQmx users will be able to enjoy the benefits of this innovation.

Independent of the current efforts of engineers, as compared with the traditional NI-DAQ (Legacy) features the advantages of the software, users can simply upgrade to the NI-DAQmx. Some of these advantages include:

Better state of model

Multi-threaded drivers

The reliability of abnormal circumstances

Simplifies the synchronization of


Procedure reduces the complexity of LabVIEW

From the simple to the smooth transition of high-level programming

Note: For more information about these benefits, and other information, please refer to ni.com on DeveloperZone available AdvantagesofNI-DAQmx Guide.

Another upgrade to the NI-DAQmx The reason is that use of the latest NI's DAQ hardware.DAQ。NIDAQNI-DAQmx。














1.  VB.NETNI-DAQmx。MicrosoftNI。

2.  VisualBasic6.0NI-DAQmx:NI-DAQmx7.4VisualBasic6.0()。C++,VisualBasic。NI,。

3.  NI-DAQVisualBasic6.0:,MicrosoftNI。





:SCXI? “ob0!sc1!md1!0”NI-DAQmx。


1.  xSCXIID。

2.  y。,1。

3.  I/channel:

·  :/ai#。 #。,SC1/MOD1/ai1ID1SCXI11。SCXI,SC1/MOD1/ai1.2.4,SCXI1、2、4。

·  :/ao#。 #。/ao22。

·  I/O:port#/line#。,。,port0/line202。

·  I/O:/ctr#。 #。,/ctr00。




CounterGroupConfigVI  DAQmxCreateChannelVI

CounterSetAttributeVI  DAQmxChannelPropertyNodeVI

CounterSource(TIO)VI  DAQmxTriggerPropertyNodeVI

CounterSource(STC)VI  DAQmxPropertyNodeVI

CounterControlVI  DAQmxStartVI

CounterGetAttributeVI  DAQmxReadVI

CounterControlVI  DAQmxStopVI



















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