Select the suitable data acquisition system for general test and measurement – Part 1

18-09-2018

 

What is a Data Acquisition System?

A data acquisition system (DAQ) is a process of measuring physical process parameters through computers and electronics hardware. The complete process requires sensors and transducers to convert the measured data into machine-readable signals, such as the popular analog voltage and current signals. Then, signal conditioning device is typically used to convert the electrical signals into data that are compatible with computer. The data acquisition hardware gathers and stores these data for analysis and controls.

Choosing a data acquisition system that can be flexible for many applications may save the company tens of thousands of dollars in the future. This type of DAQ system is typically higher-priced than their cheaper counterpart and is often overlooked by the end-users. However, low-priced data acquisition systems are generally designed to accept only one type of signal from specific transducers. More than likely, the company will be required to purchase another DAQ hardware should a requirement to process a different type of signal arises in the future. Alternatively, the company has the option to purchase a signal conditioner to convert these signals to be compatible with their current DAQ system.

Factors to consider when choosing a data acquisition system

With so many options of data acquisition system to choose from, it can be challenging to select a suitable data acquisition hardware for a specific measurement application. The users need to understand the difference between each types of signals from transducers and how their business requirements may expand in the future. In general, the users need to consider the following points to narrow the vast choices of data acquisition system to the one suitable for their need.

Required measurement channels

A DAQ hardware may contain up to 64 measurement channels in one device. It may also be daisy-chained with multiple DAQ hardware to increase total channel counts for a comprehensive measurement application. The users may choose to utilize some or all of the available measurement channels depending on their application. However, they must be aware of the fact that increasing the total active channel is compensated by the total sampling speed and resolutions of the device. As the general rule of thumb, the sampling speed needs to be at least five times of the required bandwidth to accurately construct the signals received from the sensors.

Type of signals to be processed

Sensors, transducers and signals conditioners provide a wide range of electrical signals. These input signals can be voltage, current, temperature, strain gauge, frequency, digital counter or IEPE. One may choose to select a specific DAQ system that are able to measure analog signals, voltage and current, and digital counter for their current application. However, the users will be required to purchase a new system when they need to measure other type of signals. In this case, it will be a better option to select a modular data acquisition system such as CRONOScompact from IMC (now available at Bestech Australia). It gives the users flexibility to configure their data acquisition system for their needs. This DAQ system can also be daisy-chained to up to 512 channels with other CRONOScompact devices for future scalability.

In the part 2 of this article, we will discuss the type of interfaces, connectivity, reporting requirement, sampling speed and the required resolutions.

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