Precise industrial data acquisition: The heart of the matter


The primary function of nearly every industrial application of electronics is to perform some sort of operation or function (usually with an embedded processor) based on the value of a physical “real world” analog signal. For the embedded processor to do its job, the analog signal must first be converted from analog to digital. Acquiring and converting the analog signal so that its digital representation is as close as possible to the original analog value fundamentally drives the accuracy of the measurement you can achieve and ultimately the performance of your industrial system. This is why data acquisition, or DAQ, is one of the most important subsystems of industrial electronic systems, and the analog-to-digital converter (ADC) is at the heart of the DAQ subsystem. 

Although to us most are hidden in plain sight, industrial systems play an integral role in nearly everyone’s day-to-day activities. For example, take a ride on an elevator. When the doors open, is the elevator perfectly aligned with the building floor? It’s all about the fine-grained accuracy of the motor position, measured by a high-resolution ADC in a DAQ subsystem from an optical analog motor encoder. In modern parts of today’s world, reliable electricity is so ubiquitous that we can easily take it for granted. However, there are industrial electronic systems monitoring the quality of delivered power by constantly measuring voltage and current being delivered to ensure safety and optimal power delivery. The heart of this again is an ADC. Consider an automated production line and all of the sensing complexities such as position, level, temperature and pressure. All of these measurements need to be obtained from various sources, with different electrical requirements, and done so efficiently. This can be easily done with a multi-channel ADC.

If the ADC is the heart of the data acquisition subsystem, the drive signal conditioning that interfaces to the ADC is the coronary artery. It is important to take great care in the design of the input and voltage reference drive signal, to ensure that the ADC’s performance is in top shape and uncompromised by inferior driving circuitry design. See this TI video for a thorough example of how to select an op amp to drive your SAR ADC. It walks you through the steps to design an ADC DAQ signal chain, including theory, calculation, simulation and verification using the ADCpro software.

Thoughtful selection of ADC, op amp and reference drive circuitry will promote a healthy heart in your design and precise data acquisition in your industrial system.

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