NI-9477 cRIO Power On State

[Worle]

I am using a NI-9477 in a cRIO chassis.

The datasheet for the NI-9477 states that the power on states of all outputs should be off.

In practice it appears quite a number of the outputs are on whilst the cRIO is booting up (When the FPGA is running I make the FPGA LED flash and as soon as it starts flashing the digital outputs go off which is the state they should be to begin with)

I don't think it is a wiring issue because all of the digital outputs operate normally once the FPGA has started.

Does anyone have any suggestions as to what might be causing this?

[RIObotics]

Hi,

Are you noticing that the outputs are persistent on, from cRIO boot up all the way until the FPGA is running?  Or could it be just a pulse?  You may want to double check with an oscilloscope.  

If you see a pulse. this footnote in the PDF might explain it.

"1 The module may experience a 3 ms to 4 ms glitch on the output during a chassis power cycle or software reset. Go to ni.com/info and enter info code 9477reset for more details."

[Worle]

It is not just a pulse. Some of the outputs are on consistently for ~10s until the FPGA starts.

I have run it with a stripped down version of the code which does nothing apart from start a FPGA bitfile which repeatedly sets the outputs to off with exactly the same symptoms.

I have also removed the connector from the card a probed the pins directly on the card and can confirm that the outputs are high until the FPGA has started.

This has removed any possibility as far as I can see that it is a electrical fault in my wiring (As it has been totally removed) or a software fault.

I have raised a support request with NI which has been escalated but am still waiting to hear back. As soon as I have I will post the resolution