Digital I/O

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How to output a digital signal with the PXI 6233

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Hi all,


I have to control some relays with a digital output.

For the first test I wrote this VI and it works well with the PXI 6602. These card works with TTL level.

But it doesn’t works with the PXI 6233. This card works with 24V level.


Does anyone know this issue?




Message 1 of 2
Accepted by topic author Micha_IO

Hi Michael,


I guess that your setup is not working anymore because the PXI-6602 has sourcing outputs and the PXI-6233 has sinking outputs. As shown in Figure 2 of the NI 6232/6233 specifications, the outputs of the PXI-6233 direct a load's current to ground when active:


Digital I/O Circuitry of the PXI-6233 


Therefore, you must either connect the relay's A1 input to stationary 24V and A2 to P1.x (do not forget to route P1.GND back to the power supply), or purchase the PXI-6232 card which features sourcing outputs (which provide 24V when switched on) similar to the digital I/Os of the PXI-6602.


Best regards,




Message Edited by SFK on 11-24-2008 11:22 AM
Message 2 of 2