High Impedance Measurement

[memco]

Hello,

I am interested in measuring the high impedance value of a PXI-6533 DIO.
I need to make sure that no problems occur when connected and not
used in certain parts of the test.

Ernest

[Tom_W_[DE]]

Hi Ernest-

Can you please clarify exactly what physical attribute of the device you are trying to measure?  Do you want to measure the output state of the line when the device powers up in high impedence?  Or would you like to measure the input impedence at some input node?  The pull-up/-down resistors the control and data lines are 2.2k and 100k Ohms, respectively.  So depending on which settings you choose for these lines you may be reducing your effective input impedences to near these levels.

If you can please clarify exactly what you're trying to measure I will be glad to help out.  Thanks-

[memco]

 

Ernest

I have the output of a digital board connected to the 6533. Other parts of the board are connected

to a DMM and 6120 and other cards. In past tests I tried to set the lines on the 6533 to the high

impedance mode but the measurements on the other cards would only work when the 6533

was disconnected. I want to make sure that the impedance is indeed high and would like to

measure the value.

Ernest

[Tom_W_[DE]]

Hi Ernest-

The effective input impedance should be approximately 100kOhms due to the DPULL resistors that will be installed on all the data lines.  You should be able to characterize this value by using a DMM to measure resistance between the signal pin and any DGND pin.

Hopefully this helps-