What is the input impedance on a DIO port on a 6071e? The manual just says "High Impedance".

[powerwizard]

I have the DIO line connected through a 1kOhm resistor to a sensitive analog signal and it appears to be affecting the level even though it is programmed to be an input. At certain points in my test, I change it to be an output so I can pull this line high or low as needed. I would think that the input impedance would be high enough to effectively be an open circuit.

[RIO-Todd]

The DIO lines on the E Series devices have a 50 kohm pull-up resistor between the digital lines and +5 V. Therefore, you might have to take the size of this resistor into consideration when connecting to circuitry and when you are not actively driving the digital line. If you would like the digital lines to be pulled-low instead of being pulled-high (when the lines aren't being driven) you can add a resistor between the digital lines and digital ground. The document linked below describes how to accomplish this. I hope this helps.

Setting the Default State of Digital Lines on E Series DAQ Boards
http://digital.ni.com/public.nsf/websearch/B4FED0C879BD155F862569ED00142DC7?OpenDocument

Regards,

Todd D.
NI Applications Engineer