Why You Should Consider CompactDAQ for Your Next DAQ Application

Publish Date: Feb 16, 2017 | 0 Ratings | 0.00 out of 5 | Print


A typical DAQ system consists of sensors, DAQ measurement hardware, and a computer with application software. Zooming in a little closer gives you additional items including signal conditioning circuitry, cables, sensor connectivity, and driver software that you must consider with nearly every DAQ application.

Figure 1. Parts of a Traditional DAQ System


As your application needs change, some system items might need to be added, removed, or modified. For instance, if your measurement requirements change, you may need to add new signals, sensor types, and/or features. However, you want your DAQ system to meet all of your current and future needs without having to worry about additional items. To meet the demands of your current and future applications, consider upgrading to a CompactDAQ system.


Migrating to CompactDAQ

With CompactDAQ (cDAQ), keep your current I/O configuration and gain the flexibility of adding I/O based on your need. For example, with a PCIe-6341, you are restricted to the I/O provided by the card. You need additional accessories, such as cabling and a connector block, to complete your DAQ system. With a CompactDAQ system, you can keep the I/O needed for your current application and have the ability to add I/O to the system without the additional cables or connector blocks seen in traditional systems.

Figure 2. CompactDAQ meets your needs in a portable, rugged platform unlike traditional systems.


Direct Sensor Connectivity With Integrated Signal Conditioning

Traditionally, measuring sensors with a standard DAQ device connected over PCI or USB required separate front-end signal conditioning, if measuring anything outside the normal +/- 10 V range, and in most cases an additional connector block to connect the sensors. These cables and connector blocks add costs and can contribute to noise and error in the system. New technologies and miniaturization have made the integration of sensor-specific signal conditioning and analog-to-digital conversion on the same device possible.

CompactDAQ devices combine signal connectors, integrated signal conditioning, and analog-to-digital converters (ADCs) in a single package to deliver higher accuracy measurements by eliminating error-prone cabling and connectors and reducing the number of components in a measurement system. With over 60 available C Series I/O modules supporting nearly any sensor type, you can quickly design a custom hardware setup optimized for size, cost, and performance. Each I/O module features direct sensor connectivity and built-in signal conditioning, which simplifies the hardware configuration and system design. For example, the NI 9234 dynamic signal acquisition module includes BNC connectors for quick sensor integration coupled with the signal conditioning—excitation, amplification, and filtering—required to read from IEPE sensors such as microphones or accelerometers.

Figure 3. Each C Series I/O module includes connectivity and signal conditioning for acquiring measurements from any sensor.


By including integrated connectivity and signal conditioning, C Series I/O modules move the burden of design from the engineer or scientist to the hardware manufacturer, which reduces design times and the potential for failure.



As projects grow and evolve, so do instrumentation needs. Unplanned I/O needs can arise or scaling may be a requirement from the start of the project. By starting with a modular solution from the beginning, you can add or change I/O by adding or changing modules, whereas traditional centralized systems can quickly run into limits of channel count, processing power, or sample rate just to name a few. At the other end of the spectrum, some vendor-defined solutions attempt to account for every possible application with a single solution, creating a powerful, expensive solution that adds considerable cost to any project. Ideally, instrumentation can scale from low-channel-count, simple measurements to larger, high-performance applications without adding unnecessary cost or complexity.

Figure 4. The CompactDAQ platform spans multiple buses and nearly any sensor measurement.


The CompactDAQ platform offers USB, Ethernet, 802.11 WiFi, and stand-alone controller options. By simply changing to a different chassis, you add new functionality, like WiFi connectivity or integrated computing, to existing test systems without any software changes. Additionally, with 1-, 4-, 8-, and 14-slot chassis and the ability to synchronize measurements across chassis, you can scale systems from medium to high channel counts by moving to larger chassis or synchronizing multiple chassis.


Distributable and Rugged

As applications become more complex, home-run sensor wiring approaches become more difficult and costly to implement. The cost of running sensor cable can often be the single largest line item for installing new DAQ systems once labor and capital costs are included. The alternative approach to the traditional centralized DAQ system is to distribute the DAQ devices around your application, as close to the sensor as possible, and run a single industrial network cable for data transfer back to the server or control room.

Placing the DAQ hardware as close to the sensor as possible results in a reduction in cabling that can lower costs and, more importantly, increase measurement accuracy because the shorter sensor wires to the distributed systems are less prone to noise, interference, and signal loss. Being close to the sensor can also mean the DAQ hardware can be exposed to harsh and demanding conditions where standard desktop equipment would give inaccurate data or fail entirely. Ensuring that your signal conditioning and DAQ equipment can survive your test environment can help ensure you get accurate data the first time and eliminate the need for costly retests.

Figure 5. A distributed architecture separates the system components and places the measurement devices near the physical measurement being made. 


CompactDAQ is designed to measure many channels in a small, rugged package so that you can place it close to the unit under test. CompactDAQ and all C Series I/O 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. For a more rugged option, the cDAQ-9188XT chassis and cDAQ-9134/9135 controllers can withstand operating temperatures from -40 °C to 70 °C and up to 50 g of shock. With a rugged, flexible system such as CompactDAQ, you can reconfigure and move a single test system from place to place without having to purchase different equipment for every lab or test stand.

Learn more about building distributed measurement systems



A vital piece of a DAQ system is the ADC. ADCs need clock signals to designate when samples are to be acquired. Typically, DAQ systems are based around a single timing engine, which means you select a designated sample rate for all of the acquisition channels you are sampling from. However, in some cases, you may want to go beyond this typical way of acquiring. You may want to combine sensors, requiring different sample rates, in your system without having to add additional DAQ cards and increase the cost of the system.

When it comes to timing engines, CompactDAQ systems have the advantage of flexibility. The systems provide dedicated timing engines for each function of a multifunction DAQ card and provide an additional two for the analog input channels. With three analog input timing engines, you can divide all of your analog inputs in up to three different groups with separate sampling rates. Different sample rates on the same device provide a more flexible system while lowering overall system cost.

Figure 6. Different analog input tasks can run at different rates in the same CompactDAQ chassis. 


Learn more about the NI CompactDAQ technology


One Interface, Hundreds of DAQ Devices

Most engineers and scientists can imagine the hardware implications of scaling projects to support more channels or new measurement types. Changing the number and types of measurements in a system requires new modules, connectors, wires, and enclosures, in addition to many other physical hardware changes. What may not be as evident are the required software changes. Having a common software platform that can handle 1,000 channels as easily as 10 channels, with ways to efficiently add additional analysis and signal processing, can simplify the complexities of scaling a measurement system. Both the hardware driver and the application software need to account for additional requirements.

The hardware driver for CompactDAQ and nearly all NI DAQ devices is NI-DAQmx. The driver provides a single programming interface for hundreds of DAQ devices so you have to learn the interface only once. Whether you are developing with an X Series USB device or a CompactDAQ device, the basic DAQ code is the same. With a single programming interface, you can upgrade or switch hardware without changing your code.

Figure 7. NI-DAQmx driver software abstracts DAQ bus technology and provides a consistent API across multiple programming languages.


Learn more about moving your NI-DAQmx code across NI DAQ devices


CompactDAQ—The Right Platform for Your Measurement Application

With over five billion combinations of I/O, the CompactDAQ platform can scale and adapt to any project scope or budget. Direct sensor connectivity, integrated signal conditioning, and support for the most common PC buses ensure that you are equipped with the tools you need to innovate faster.

Still not sure you can make the switch? With local NI support engineers, you have the help you need to ensure your exact measurement application requirements are met.

Not sure where to start? Use the CompactDAQ online product advisor to configure a complete system with the level of flexibility and I/O options your application demands.

Build your own CompactDAQ system

Specifications Explained: cDAQ and cRIO Chassis and Controllers

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