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[Digital Output Problem] PCI-DIO-96

I am using a NI I/0 card (PCI-DIO-96) with DAQmx libraries under Linux.


I compiled and run the example WriteDigChan.c.


After i run this example, i used a multimeter to measure the voltage at each line and check if the card is working properly.


The problem is that when a line is set to logic low (0) the voltage i measure is ~4,916 Volts and when a line is set logic high (1) the voltage i measure is 0 Volts.


Shouldn't be viseversa? Or am I missing something?


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Message 1 of 3

Hi Insomnia,


This card is probably active low output by default - meaning that a low (0) will result in an active voltage. In this case since your Vcc seems to be 5V, a 0 output will result in roughly 5V being output. This also means that a logical 1 will be ouput as around 0V.


You can invert the lines using the DAQmx property function call DAQmxSetDOInvertLines.

Mathew H.
Applications Engineer
National Instruments
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Message 2 of 3



I used this board years ago and the outputs are not inverted or active low.

The output should be as expected a '0' is 0V and a '1' is 5V.


Are you not measuring between a output and the +5V ??



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