Why does PXI 6224 give a channel voltage and all channels have the same value？

[OTGZzz]

The voltage of PXI 6224 in the real-time system is collected through veristad. I give a channel 3V voltage, and the 32 channels collected are 3V. Measured with a multimeter, only the first channel has voltage。Such as the attached picture。I don't know how to deal with him, ask for help。。。。。。。

[santo_13 · Accepted solution]

A most common reason for such thing happening would the because the additional channels are not connected to any signal and the signal on one channel is inducing a charge on the rest of the channels. Instrument with high input impedance is not recommended to be left floating.

Please connect any unused Channel to GND to avoid this behaviour. This is similar to OPAMP where the inputs should never be left floating and inputs of any unused OPAMP in a package should be grounded.