By PURPLELEC | 08 June 2023 | 0 Comments
What are the functions of USB data acquisition card
The functions of a typical data acquisition card (USB data acquisition card) include analog input, analog output, digital I/O, counter/timer, etc., and these functions are respectively realized by corresponding circuits.
Analog input is the most basic function of acquisition. It is generally realized by a multi-way switch (MUX), an amplifier, a sample-and-hold circuit, and A/D. Through these parts, an analog signal can be converted into a digital signal. The performance and parameters of the A/D directly affect the quality of the analog input, and the appropriate A/D should be selected according to the actual required accuracy.
The analog output is usually used to provide excitation for the acquisition system. The output signal is affected by factors such as the settling time, conversion rate, and resolution of the digital-to-analog converter (D/A). Settling time and slew rate determine how quickly the output signal amplitude changes. A D/A with a short settling time and a high conversion rate can provide a higher frequency signal. If the output signal of the D/A is used to drive a heater, there is no need to use a fast D/A, because the heater itself cannot track voltage changes very quickly. Therefore, the parameter index of D/A should be selected according to actual needs.
Digital I/O is usually used to control the process, generate test signals, communicate with peripherals, etc. (USB data acquisition card) Its important parameters include: number of digital ports (line), receiving (sending) rate, driving capability, etc. If the output is to drive electrical appliances such as motors, lamps, and switching heaters, a high data conversion rate is not required.
The number of channels must be compatible with the control object, and the current required is less than the drive current that the acquisition card can provide. However, with the addition of suitable digital signal conditioning equipment, the low-current TTL level signal output by the acquisition card can still be used to monitor high-voltage, high-current industrial equipment.
A common application of digital I/O is to transfer data between a computer and peripherals such as printers, data loggers, etc. In addition, some digital ports also have "handshake" lines for synchronous communication. The number of channels, data conversion rate, and "handshake" capability are all important parameters, and digital I/O with appropriate parameters should be selected according to specific applications.
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