why is there an erroneous signal on AI0 out of the NI-6216 when it's _not_ connected to USB?

[sim_dlr]

I'm using the NI-6216 for digital and analog I/O. If the device is turned off (no USB connection) and there are digital and analog signals on inputs, one of the analog signals on the input is erroneous: there's always a voltage offset between +0,2V and +0,8V. This effect disappears if the device is powered up and active or if the signal is disconnected from the NI-6216.

All signals are single-ended and share the same GND.

Why does that happen? What happens to the analog inputs if the device is off?

[fendrix]

Hello,

I'm not sure if I understand you right. You have the device switched on but no USB cable inserted. Than you connect some signals to the inputs and you notice that an analog signal on the input provides wrong values. But how do you measure that signal when the device isn't connected to a PC.

Please tell me, if I get you right or try to define your problem more precisely.

Best regards and a nice weekend,

Frank