Persistent digital output for PXI-6528

[BrianCEmbed]

Our team has a station computer that is connected via a remote control card to a PXI chassis (from Teradyne) which contains two PXI-6528 digital I/O cards. On one of those cards, we have two of its outputs (for simplicity I will call them A and B) connected to a power-control unit (PCU) which controls the power state of sensitive equipment. When A is logic low, and B is high, the output of the PCU is user-selectable via buttons on its front panel. When A and B are both set high or low, then the PCU output is forced into the on or off state (I am not sure which is which).

The problem is that when the PCU is in the on state and the station computer is then shut down or restarted, the PCU switches off, risking damage to the equipment. We have configured the DIO card in NI MAX so that power-up configuration of A and B is to the user-selectable state, so I would expect the PCU to hold its power state when the station computer turns off. My assumption has been that NI MAX queries the EEPROM of each card for its current power-up configuration when the configuration panel opens, giving me confidence that at least this element would be correctly set up. So far, we have not been able to figure out when PCU shuts off.

Is the something I am missing with regard to NI MAX or these NI DIO cards that could be linked to my issue?

I would appreciate any help. Thank you.

[santo_13]

Do you even realize when the PC switches off, there is no power supply to the DAQ for it to maintain the digital output state?

The configurable power-up state is only for power-up not when there is no power to the card.

Edit - realized late that you have a PXI chassis not plugged into the PC, anyway, it looks like the PC restart is also restarting the PXI

[santo_13 · Accepted solution]

Do you know if the PXI also power cycles when you shut down or restart the PC?

If it does, then it is clear that you need to configure the PXI chassis not to power cycle when the PC restarts. Please share the model of PXI, remote control module on both PXI and PC side, and related manuals.

[BrianCEmbed]

Our initial feedback from the PXI chassis manufacturer is that is how the chassis functions and it's not something we will be able to address directly, but only mitigate through user training and user interface guards.

Thank you, santo_13 for your help.