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9421 input impedance

Does anybody know what the input impedance of an NI 9421 is?
Thanks,
Bryan
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Hi Bryan,

We do not spec an input impedance for this module because the inputs use a current-limiting architecture, so the input impedence is dynamic based on the voltage.  You could use the <7mA max input current spec in conjunction with your expected source voltage to calculate a pseudo minimum input impedence.  Keep in mind that this is dynamic and the 7mA value is more of a guideline since it is dependent on the circuit you have attached to the input of the NI 9421.

Regards,
Andrew W
National Instruments
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