USB-6009 - Some DIO channels go high at start-up?

[Jclev19]

We're using twin USB-6009 multi-function DAQ boards to collect data and control some basic instruments (relays & solenoids, etc..), and I've found that on one board, a few of the DIO channels go to 5V at start-up and stay there until I reset in either Labview or using the NIMax s/w.  As this can overheat my solenoids and relays, I was wondering if my USB-6009 has failed, or if there is a way to avoid this from happening.

Thanks,

Jason

[Wayne.C]

DIO lines on USB-6009 are by default open collector with an internal pullup resistor.  The best solution is to rewire your circuit so that the the DIO lines are sinking current and not sourcing.  In the case of a solenoid valve, you would hardwire +V to one side of the solenoid and use the DIO line to switch common to other side of coil.  When output is high, no difference in potential across coil and no current to energize.  When output is low, potential across the coil and current to energize.

[Jclev19]

Thanks - we originally had the line running through a follower, to the solenoid-controlling relay.  I reversed the line polarity and switched the wiring so the it acts as the current sink, and all is well.