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I am sharing an appliance which contains LEDs that either of two PCI DIO 96 cards can sink the LED to turn it on - a 'wired-or' condition. This works great as long as both of the PCI DIO cards stay active.
When one system containing the DIO card is powered off, the LED at the appliance illuminates overriding the chance of the other system using it.
is there a way to command (or strap) the PCI DIO 96 card to go to a 'high impedance' or HIGH state when powered off?
Digital outputs on NI cards aren't able to go to a specified state when the card is not powered. The PCI-DIO-96 has internal bias resistors to pull the lines high to +5V when powered on, but when the card isn't powered, the +5V Vcc line is not powered, so the lines will not stay high.
You might be able to use an external bias resistor to keep the line pulled high when the card is powered off, but it isn't really a case that the card was designed for.
