Many National Instruments devices utilize Analog-to-Digital Converters, which has many advantages, including improving preciseness and performance within a variety of applications. There are two key types of Analog-to-Digital Converters or ADCs used in National Instruments DAQ Devices: the Successive-Approximation-Register or SAR and Delta-Sigma ADC or DSA. The SAR type of ADC is utilized in NI-63xx X Series Devices and Modules, NI-60xx E Series Devices, several NI-61xx S Series Devices and Modules, and NI-62xx M Series Devices and Modules. However, the DSA type of ADC is utilized in NI-43xx SC Express Devices and Modules, NI-944xx DSA Devices and Modules, and several NI-92xx C Series Devices and Modules.
The SAR ADC takes in an ongoing analog signal into a discrete arrangement using an approximation trigger. The SAR ADC uses a binary algorithm to change ongoing analog waveforms into tinier discrete outputs. Every analog point is monitored to determine if it is bigger or smaller than a digital reference point. When the point is bigger, the digital bit is set to high, or 1 in binary, then transported to the following bit. When the point is smaller, then it is set to low, or 0 in binary, then transported to the following bit. This process transpires until the analog point conversion is finished.
The second type of ADC used in National Instruments DAQ Devices, DSA ADC, uses decimation filter, oversampling, and noise shaping to generate applications with excellent antialiasing filtering and high resolution. The DSA is free-running, so it is sampled before any trigger settings. Therefore, the DSA is ideal for strain and pressure measurement, along with audio signal and vibration assessment. The SAR A D Converter National Instruments is used in numerous high-performance DAQ devices.
In the SC Express Series, the PXIe-43xx Bridge Input Modules utilize 24-bit DSA ADCs to complete simultaneously sampled, extremely precise strain-gage and Wheatstone bridge-based measurements. These Bridge Input Modules are normally utilized for pressure, load, and strain measurements in structural assessment applications.
The C Series Devices and Modules with ADCs utilize DSA ADCs to perform extremely exact measurements for applications, such as high voltage and current, DSA, universal, thermocouple, and bridge-based measurements.
ADC quality effects measurement preciseness regarding digitizing a real-world signal into its binary depiction. For example, ADCs with a higher resolution can measure tinier signals. In addition, quicker sampling rates can acquire more of the base analog signal in the digital depiction. Certain ADCs from the M Series and S Series of DAQ Devices even have more than one ADCs. One example of a NI device with multiple ADCs is the PXI-5105 Digitizer, which has eight 12-bit ADCs. As technology increases, this lowers ADC module prices and improves performance. NI is continuously working on enhancing analog measurement features with more affordable, high-performing devices.