USB-6251 AO AI

[pacino21]

各位好，

我用USB 6251做一个模拟信号生成和采集实验，过程如下：将AO0（PIN15）与AI0（PIN1）相连，AIGND与AOGND相连，在Labview中编程输出偏移为零正弦波（过零点）电压信号，从AI0采集

问题是，为什么我采集到的正弦波信号有偏移，且偏移大小不定，从-0.75V到-2.23V都有？难道AO通道与AI通道存在电势差？

另：将AIGND与AOGND断开也是一样的情况，采集信号的偏移不是零。

[pacino21]

Hi everyone,

I did a simulation in USB-6251: connect AO0(PIN15)to AI0(PIN1), and AOGND to AIGND, and then I make a programme in Labview to output sine waveform vlotage (offset voltage=0) to AO0 and acquire it in AI0. the problem is the waveform I acquired from AI0, its offset is not 0, is -1.75V, -2.0V, -2.23V........ I cann't understand that. the waveform I acquired should be the same as I generate, is that right?

thanks