How to Select the Ideal Portable DAQ System

Measure Temperature, Current/Voltage and more
CHESTERLAND, OH—February 29, 2016

Portable data acquisition systems are convenient solutions used to log data and monitor temperature and other values in industrial and laboratory applications. These compact devices perform Quality Control and Process Overview, and can often monitor multiple parameters in different tasks. However, selecting the most appropriate DAQ system for a project requires careful consideration. In this latest CAS DataLoggers White Paper, we examine the key factors to consider when deciding on a measurement system for your specific application.

Asking the Right Questions:

When selecting a portable data acquisition system for their needs, users face a bewildering choice of available manufacturers, models and specifications. Each system has its own configurations that make some units more suitable than others for certain applications. Anticipating your future project’s needs now will save time and money on installation later.
Data acquisition system designs range from the simple to the complex, with a related variety in performance, options, and cost. Fortunately for purchasers, this search can quickly be narrowed down by considering several important factors:

Accuracy and Speed:

Of course, the main function of data acquisition systems is their ability to accurately collect data, i.e. their accuracy specification. While there is a wide range of models in the market, field measurement accuracy is heavily based upon the particular sensors you plan to use. For most sensors calibrated in a laboratory and installed in the field, accuracies in the range of 0.01 % to 1% of full scale are typical, with many other sensors having less accuracy.

The particular system’s input types must match your project requirements. While you ensure that the data logger supports the specific sensors you’ll use to collect data, also check that the device has adequate memory and storage to support any and all of your specific projects. Likewise, the sampling speed of DAQ systems must also be taken into account when determining accuracy. Sampling rates are available in a wide variety from as low as once per day to higher than a million measurements per second! Regardless of its accuracy, the device must also acquire signals quickly enough to avoid any data loss. The necessary data acquisition speed is calculated by using Nyquist’s Sampling Theorem, which states that a signal must be sampled at twice the frequency of the spectral signal components of interest in order to accurately reconstruct the waveform.

Signal Conditioning and Standalone Operation:

Choosing a portable data acquisition system featuring internal signal conditioning capabilities can greatly improve system quality and performance. Different types of signal conditioning include amplification, attenuation, and filtering. As always, your specific application and sensor types will decide the type of signal conditioning required.

For example to measure temperature, a device will probably need to use either thermocouples or thermistors. Thermocouples produce a voltage varying with the temperature, but connecting a thermocouple to a data acquisition system creates a cold junction point at the terminals that acts as a thermocouple itself. Signal conditioning is required to compensate for this, or else the recorded temperature which is taken from the total voltage will be altered by the additional voltage of the cold junction point.
Signal conditioning can also be used for signal amplification to mitigate any noise distortion, and is also useful when a DAQ device is connected to other transducers such as strain gauges, accelerometers, etc.

Next determine if you need a standalone solution (a system operating independent of a PC). These devices are powered by either a self-contained battery or a single DC power source, requiring no other connection to function other than the sensors being monitored. If instead you require PC connection, many data acquisition systems utilize a local co-processor to take the load off of the PC operating system and to help prevent OS crashes.

For remote applications where access to a standard 120V AC power outlet isn’t available, electric power to the system can be provided either through an internal battery pack, or the user can connect an external wire to a DC power supply. Additionally, in order to conserve power and avoid unnecessary processor loadup, users with minimal processing requirements can select a lower performance CPU and rely on a capable storage system.

Surviving in the Field:

DAQ systems represent a considerable investment of time and cost, so their protection should be paramount. Do you need a highly durable, ruggedized system? This depends on how often you plan on transporting the device. The ideal portable measurement system for most users is a lightweight, compact unit for easy installation in a test stand or within an industrial enclosure.

Do you plan to install your system in a potentially hazardous environment such as a factory floor? If so, carefully consider any potentially damaging extremes including high temperature/humidity, shock and vibration. For example if liquids/dust are a concern, you should consider systems with a high IP (Ingress Protection) rating and/or use an enclosure.

Portable data acquisition units also need to be able to survive in high shock and vibration environments such as the trunk of a car or onboard an airplane, including the occasional accident such as someone dropping it! Other sealing and packaging precautions such as watertight housing should also be considered for water and wastewater applications.

Choose How You Communicate:

For many users, Ethernet or USB are easy options for retrieving data, but if your system needs to log measurements in remote locations, it will need a wireless means of communication with your PC or wireless network.
When designed to monitor remote unattended systems, suitable DAQ devices have communications capabilities utilizing telephone connections or wireless systems to download data to remote PCs. They also require ample built-in storage and user interfaces to enable setup and control. Advanced solutions use their own built-in test capabilities, allowing users to sit back as the system acquires the data.

Software:

While some systems include software in their price, many others require one or more software as an add-on cost. Be direct with your distributor regarding software costs and any applicable licensing fees. This same advice goes for a system featuring cloud data storage, which may require a subscription or monthly fees.

When analyzing recorded data and exporting it to other formats for analysis, many users rate software primarily by how user-friendly it is. This often depends on the graphical interface style, menu navigation, and help tips. Continuing with the earlier example, the Delphin Expert Key series features ProfiSignal software for data storage, trend display, and analysis.

Summary:

Taking into account these important factors when choosing the right portable DAQ device is certainly an involved process, but one made much easier by keeping the needs of your present and future applications foremost in mind. With this initial consideration done, you’ll be in a strong position to search for the right system to match your needs.

View several models of data acquisition systems for your application-specific needs on our DAQ System page, contact a CAS Data Logger Applications Specialist at (800) 956-4437, or visit our website at www.DataLoggerInc.com.

Contact Information:
CAS DataLoggers, Inc.
8437 Mayfield Rd.
Chesterland, Ohio 44026
(440) 729-2570
(800) 956-4437
sales@dataloggerinc.com
www.dataloggerinc.com

This release was published on openPR.