Figure 1. The NI cDAQ-918x Gigabit Ethernet chassis expand the NI CompactDAQ platform to remote or distributed measurement applications.
1. Ethernet Data Acquisition
Ethernet data acquisition is an extension of PC-based data acquisition to measurement applications distributed over a large area or network. NI Ethernet DAQ devices combine industry-standard Ethernet communication, industry environmental certifications, NI C Series modular I/O, and the flexibility of NI-DAQmx software for remote monitoring and control of electrical, physical, mechanical, and acoustic signals.
Ethernet offers three advantages over other common PC peripheral buses: long cabling lengths, network infrastructure, and ruggedness. Ethernet is ideal for taking measurements at distances beyond the 5 m limit of a USB cable. A single CAT 5E cable can reach 100 m before needing a switch or router to carry the signal farther. Furthermore, many IT departments have standardized on Gigabit Ethernet (IEEE 802.3ab) as the foundation of their corporate networks.
With NI CompactDAQ, you can take advantage of that existing infrastructure and additional network bandwidth for your remote or distributed measurement applications. One host computer can manage multiple test stations within the same facility or across multiple sites. In fact, as long as an IP network connection exists, you can access an NI CompactDAQ system from anywhere in the world.
Figure 2. You can access an NI CompactDAQ Ethernet chassis from anywhere with an IP network connection.
NI CompactDAQ is a modular data acquisition system that provides sensor and electrical measurements on the benchtop, in the field, and on the production line. With more than 50 different C Series I/O modules to choose from, you can build remote or distributed, high-speed measurement systems using standard Gigabit Ethernet infrastructure and create an optimized system exactly for your application without paying for unneeded functionality. NI CompactDAQ simplifies initial setup with Zero Configuration Networking (Zeroconf) technology and a built-in, web-based configuration and monitoring utility.
Figure 3. NI CompactDAQ Ethernet DAQ Systems
2. NI Signal Streaming Over TCP/IP
To take advantage of the 1,000 Mbit/s of bandwidth on a Gigabit Ethernet network, NI CompactDAQ chassis implement a TCP/IP version of the same patented NI Signal Streaming technology found in high-performance NI USB DAQ products. With this technology, new high-speed C Series modules, such as the NI 9223, can continuously acquire up to 1 MS/s of simultaneous 16-bit data on each of four channels. Using sophisticated software architecture, NI-DAQmx driver software maintains a double-buffered transfer mechanism between the chassis and host computer capable of sustaining several bidirectional continuous waveforms. At the same time, the driver monitors the state of the network to adjust for unexpected delays or temporary interruptions due to network traffic. All of this is abstracted from the user, so you can focus on the measurement application and not the network.
Figure 4. Patented NI Signal Streaming technology enables parallel streaming of high-speed, bidirectional data from multiple measurement tasks over TCP/IP.
3. Zero Configuration Networking
Traditionally, the process of network configuration and administration has not been for the timid. To make networking technology more accessible to the non-IT professional, NI CompactDAQ Ethernet chassis use the Zeroconf standard. Zeroconf is a collection of three technologies:
- Link-local addressing provides automatic IP addressing without a DHCP server.
- Multicast DNS (mDNS) automatically resolves and distributes host names without a DNS server.
- DNS Service Discovery (DNS-SD) automatically finds network services such as printing or data acquisition.
With Zeroconf technology, you can plug an NI CompactDAQ system directly into your computer or local subnet, and it appears automatically in the NI Measurement & Automation Explorer (MAX) configuration utility without any network setup or configuration.
In addition, a new web configuration interface built into the firmware of the NI cDAQ-918x helps you manage your system through a web browser without installing any software on your host machine. You see the same configuration screen whether you use a web browser or MAX.
Figure 5. With the embedded web server on the cDAQ-918x chassis, you can remotely configure your NI CompactDAQ system from a web browser or from MAX.
Watch a video demonstration of the web-based configuration for NI CompactDAQ
4. Mixed Measurements With Multiple Timing Engines
NI CompactDAQ Ethernet systems provide the flexibility of measuring low-speed DC data and high-speed dynamic signals in the same instrument. The chassis backplane includes the NI-STC3 timing and synchronization controller, which can manage up to seven hardware-timed data streams for multiple analog I/O, digital I/O, and counter I/O measurement tasks. Combined with your choice of more than 50 different C Series I/O for measurements such as temperature, pressure, voltage, acceleration, current, resistance, and strain, this technology enables the NI CompactDAQ platform to provide a broad spectrum of I/O capabilities for mixed-measurement systems. You can install a thermocouple module next to an accelerometer module and acquire from both modules simultaneously at different rates because each can synchronize to a separate timing engine. This alleviates the need to decimate or parse lower speed data from the higher speed data.
Figure 6. More than 50 different sensor-specific C Series I/O modules are available for creating custom, mixed-measurement systems.
For more information on C Series hardware or a list of compatible modules, see the compatibility table.
5. Reliable Measurements in Rugged Applications
You can create an optimized system exactly for your rugged application without paying for unneeded functionality but with the flexibility to adapt to changing requirements over time. NI CompactDAQ and all C Series modules are constructed from A380 cast aluminum for a rugged system that can withstand operating temperatures from -20 °C to 55 °C, and up to 30 g of shock. A more rugged version of the NI CompactDAQ Ethernet chassis, the NI cDAQ-9188XT, can withstand operating temperatures from -40 °C to 70 °C and up to 50 g of shock. The shock and vibration specifications are all tested on an NI CompactDAQ system with modules installed, so modules do not fall out or come undocked under the specified conditions. The Ethernet NI CompactDAQ chassis systems also have already gone through the rigorous testing and come with the UL‘s Hazardous Locations (Class 1 Division 2) and Ex certifications. The rugged features of NI CompactDAQ Ethernet chassis help you quickly begin testing because less time is needed to prepare the instrumentation for the rigors of field testing.
Figure 7. The NI cDAQ-9188XT brings a temperature range of -40 °C to 70 °C, 50 g shock, and 5 g vibration to the NI CompactDAQ family so you can take any measurement, anywhere.
6. Detect, Configure, and Acquire Within Minutes
NI Ethernet DAQ devices are shipped with the NI Measurement & Automation Explorer (MAX) test and configuration application. This is the same utility (Figure 8) that all other NI hardware uses, so all of your devices, regardless of the peripheral bus you use, show up in the same place. Ethernet DAQ devices are configured the same way as any other networked device such as laptops or gaming systems. An Ethernet DAQ device can operate with either a static IP address or one dynamically assigned from a DHCP server. Once your system detects the device, you can remotely change the configuration settings, test the connected sensors, or begin programming your system with the NI-DAQmx driver.
Figure 8. MAX Configuration Utility With NI cDAQ-9188 Chassis
7. NI-DAQmx and NI LabVIEW—The National Instruments Data Acquisition Difference
You can develop measurement and test applications in multiple programming environments, including ANSI C/C++, C#, LabVIEW, and Microsoft Visual Basic .NET. With NI-DAQmx and the ubiquity of the Ethernet networking infrastructure, NI Ethernet DAQ makes it easy to incorporate remote connectivity into new or existing PC-based measurement or control systems.
Tight hardware/software integration makes the LabVIEW graphical development environment a smart choice for getting the most performance out of your Ethernet DAQ system with the least programming effort. Development time and flexibility are the two main advantages to developing a system with LabVIEW and NI-DAQmx. NI-DAQmx is the API that is shipped with all NI DAQ devices. When programming with LabVIEW, NI LabWindows™/CVI, or NI Measurement Studio, you have access to the DAQ Assistant (Figure 9), a graphical wizard-style programming interface that guides you through acquiring data with your NI device. The DAQ Assistant significantly reduces the development of your DAQ code by turning your configuration settings into running code.
Figure 9. NI DAQ Assistant Configuration Screen
In addition to the DAQ Assistant, LabVIEW has hundreds of built-in functions for analysis, alarming, reporting, and file I/O that further reduce your application development time. Because you are developing with LabVIEW programming, the functionality of your system is not limited. As your project grows or changes, you can modify your code to meet the new requirements. LabVIEW also helps you eliminate the need for multiple software programs for a single process. There are thousands of third-party devices on the market that have drivers written for LabVIEW. You can easily integrate these devices into any LabVIEW program. For those devices that do not have a full driver, you can use a development API to integrate the new hardware device with your system based on LabVIEW.
8. Additional Information
The mark LabWindows is used under a license from Microsoft Corporation. Windows is a registered trademark of Microsoft Corporation in the United States and other countries.