NI C Series Embedded Measurement and Logging Systems

1. Platform Overview
2. Comparison of Stand-Alone NI CompactDAQ and CompactRIO
3. Related Links

Platform Overview

You can use NI CompactDAQ and NI CompactRIO systems within a variety of embedded measurement and logging applications. Both platforms use the same C Series I/O modules that allow connection to a variety of sensors, signals, and actuators.

The NI CompactDAQ stand-alone system represents an embedded platform that is well suited for high-performance embedded measurement and logging applications where control is not required. With NI CompactDAQ, design teams can use NI LabVIEW software along with the NI-DAQmx driver and quickly build high-performance embedded measurement and logging systems.

The CompactRIO platform contains an embedded field-programmable gate array (FPGA) programmed with the LabVIEW FPGA Module and is well suited for applications that require measurements along with closed-loop control. With CompactRIO, design teams can use LabVIEW FPGA along with the NI-RIO driver to build advanced control and monitoring applications.

Table 1. Stand-alone NI CompactDAQ and CompactRIO are best suited for different types of embedded monitoring and logging applications.

Comparison of Stand-Alone NI CompactDAQ and CompactRIO

CompactRIO provides solutions optimized for low-cost high-volume deployments, harsh environments, and high-performance processing. From a processing and mechanical standpoint, stand-alone NI CompactDAQ is most similar to the highest performance CompactRIO systems. Table 2 compares the two solutions in detail.

Table 2. Compare the details of stand-alone NI CompactDAQ and CompactRIO.

Embedded Controller

Stand-alone NI CompactDAQ has built-in controllers with options for Celeron and Core i7 processors. These same processors are embedded in the highest performing CompactRIO controllers. These high-end processors are ideal for applications that require intensive signal processing and analysis as needed for conditioning monitoring prognostics and vision processing. CompactRIO also includes a number of other processors including PowerPC real-time processors.

C Series I/O Modules

NI CompactDAQ and CompactRIO both support more than 50 C Series I/O modules including various analog and digital I/O, as well as embedded network communication like CAN and LIN. The analog modules include sensor-specific signal conditioning and connectivity for thermocouples, resistance temperature detectors (RTDs), pressure sensors, accelerometers, and microphones. CompactRIO systems support additional modules for motion, vision, and industrial communications protocols. CompactRIO also supports more than 50 third-party modules written by NI Alliance Partners. The different module support is due to the programming paradigms available for NI CompactDAQ and CompactRIO.

Measurement Timing

With NI CompactDAQ, I/O modules are automatically synchronized, and a single NI CompactDAQ system can simultaneously stream high-speed analog input, analog output, digital input, and digital output at the same time. The analog-to-digital converter (ADC) is a vital piece of any measurement system to designate when samples are to be acquired. Many systems have multiple ADCs that share the same clock to synchronize all of the channels’ measurements. NI CompactDAQ systems have the advantage of flexibility when it comes to timing engines and go beyond this standard synchronization.

NI CompactDAQ chassis have three analog input timing engines. This gives programmers the ability to divide all of their analog inputs in up to three different groups known as “tasks.” Each task can run at a separate rate. This is ideal when combining temperature measurements, which are often slow, with higher speed measurements such as sound and vibration. The three tasks operate independently but can be started simultaneously. All channels within a single task are automatically synchronized and returned at the requested rate. All modules can be combined in a single task to easily synchronize all channels to the same clock.

NI CompactDAQ was designed to perform up to seven tasks simultaneously. You can choose from several task options:

• • Analog input with up to three timing engines
  • Analog output with designated timing engine
  • Digital input with designated timing engine
  • Digital output with designated timing engine
  • Counter/timer tasks for quadrature, PWM, event, period, or frequency measurement

By having a designated resource, digital and analog output tasks can run independently without having to share a clock signal from another task. This makes the programming easier and more intuitive. The multiple timing engines and ability to route and share resources provide a level of flexibility to NI CompactDAQ unequaled by most off-the-shelf data acquisition systems.

The timing features of NI CompactDAQ cover the vast majority of measurement requirements. For applications that require further customization, you can program the FPGA on CompactRIO to meet the most advanced timing and signal processing requirements.

Software

NI CompactDAQ and CompactRIO support Windows Embedded and LabVIEW Real-Time OSs. In both use cases, LabVIEW system design software gives you the ability to build powerful applications with acquisition, analysis, and visualization software in a single environment. LabVIEW provides a software solution that is flexible enough to meet your requirements today and adapt with changing requirements and technologies over time.

The two platforms require different driver-level software to interact with the hardware. NI CompactDAQ takes advantage of NI-DAQmx driver software that is optimized for high-speed waveform acquisition tasks. With NI-DAQmx, you can automatically synchronize all of your data and scale channel counts and measurement types on the fly. NI CompactDAQ also supports the NI-XNET driver for programming the embedded networks modules (ie: CAN and LIN). NI-DAQmx and NI-XNET driver software also support text-based programming languages including Measurement Studio, CVI, Visual C++, and Visual Basic. Users interested in NI CompactDAQ have the flexibility to choose between LabVIEW and various text-based programming languages. For NI CompactDAQ applications that require long-term continuous uptime, you can use LabVIEW Real-Time to deploy applications to a headless, reliable system.

CompactRIO uses the NI-RIO driver, which gives you the ability to target FPGA-based reconfigurable I/O. The NI-RIO driver, LabVIEW, and CompactRIO make FPGA technology easily accessible, so you can define your own control circuitry while reducing the complexity and costs associated with traditional custom hardware. You also have the option of using the LabVIEW FPGA Module to directly target the FPGA to create custom measurement and control hardware using graphical programming without having expertise in low-level hardware description languages or board-level design. You can use the FPGA for unique timing and triggering routines, high-speed control, interfacing to digital protocols, digital signal processing (DSP), and many other applications requiring high-speed hardware reliability and tight determinism.

Environment

Stand-alone NI CompactDAQ and multicore CompactRIO have industrial operational specifications for temperature, vibration, and shock. For the most extreme environments, ultrarugged CompactRIO variations are also available .

Applications

Because of the NI-DAQmx driver software and high-throughput streaming rates, stand-alone NI CompactDAQ is ideal for high-speed waveform acquisition. NI designed stand-alone NI CompactDAQ to be optimized for measurement applications. The hardware architecture is not intended for closed-loop control applications due to the jitter on the order of 10-100 ms. CompactRIO is best suited for single-point closed loop control applications because of the programming API and the less than microsecond jitter required for advanced control applications.

Related Links

Learn more about stand-alone NI CompactDAQ

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Reader Comments | Submit a comment »

This article does not discuss logging. Where do the systems log data to, and how is it retrieved?
- David Levine,Ducommun Tech. dlevine@ducommun.com - Sep 04, 2012