(1) Number of channels: that is, the board can collect several channels of signals, which are divided into single-ended and double-ended (differential). Commonly used are single-ended 32-way/differential 16-way, single-ended 16-way/differential 8-way.
(2) Sampling frequency of data acquisition card: The number of data points collected per unit time is related to the time required to convert one point of the AD chip. For example: T=10us is required for AD conversion of one point, then its sampling frequency f=1/T is 100K (ie 100kHz), that is, the AD chip can convert 100K data points per second. There are often 100K, 250K, 500K, 800K, 1M, 40M, etc.
(3) Cache: mainly used to store the data converted by the AD chip. The sampling frequency can be set for the board with cache, otherwise it cannot be changed. There are two types of cache, RAM and FIFO. FIFO is mainly used for data buffering, with small storage capacity and fast speed; RAM is generally used for high-speed acquisition cards, with large storage capacity and slow speed.
(4) Resolution: The value of the quantity represented by the lowest bit of the sampling data, usually 12 bits, 14 bits, 16 bits, etc. Such as 12-bit resolution, when the voltage range is 5000mV, the unit increment is (5000mV)/4096=1.22mV (Note: 2 to the 12th power is 4096).
(5) Accuracy: The error between the measured value and the true value, that is, the measurement accuracy. It is generally expressed as a percentage of full scale FSR (Full Scale Range), such as 0.05%FSR, 0.1%FSR, etc. If the full-scale range is 0~10V, the accuracy is 0.1%FSR, and the error is within 10mV.
(6) Range: The amplitude of the input signal, commonly used are ±5V, ±10V, 0~5V, 0~10V.
(7) Gain: the amplification factor of the input signal, divided into program-controlled gain and hardware gain. The AD converted data is amplified by a fixed multiple through the voltage amplifier chip of the data acquisition card. There are two types of gain chips: PGA202 (1, 10, 100, 1000) and PGA203 (1, 2, 4, 8).
(8) Data acquisition card trigger: It can be divided into two types: internal trigger and external trigger, specifying the way to start AD conversion.