How does short input noise level pertain to the NI 6225?

[Seth_B.]

Generally, you use a cable connected to a terminal block such as the SCB-68, BNC-2110 or the CB-68LP.  Dismantling a cable isn't really ideal, as the internal wiring will be difficult to sort out easily.  If you are testing the noise present when reading with the DAQ card, you should use the function generator, not the Oscope.  You'll want to connect it to AI0+ and AI0-.  You can find the pin mappings for these in the NI-6225 specifications and you can use Measurement and Automation Explorer to do the testing.'

Regards,

[etechstan]

Seth, I got the SCB-68 and have a good idea on how to start this but what signal will I input?  (I'm sort of a novice)

[Seth_B.]

A DC signal would be easiest to determine the noise you are seeing.  If you want to really simplify things, just connect a wire between the AI0+ channel and AI0- and test that.  That will show you the noise on a grounded signal.  If you want a more detailed test, connect a 9V DC signal from your function generator and measure that using the MAX test panels as well.  As you get closer to the boundries of your input range, your noise will be greater.

Regards,

[etechstan]

You mean jump these together, there's no risk of damaging anything?

[Seth_B.]

As long as it is just the AI channel and ground, it's fine.  That just puts both channels at ground potential, which doesn't risk damage to the card.

[etechstan]

Once I can break away from this paperwork, I'll give it a try.  Thanks