Archived:Archive-Power-on After Clearing CMOS on a PXI Express Controller

Updated Jan 9, 2018

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Issue Details

My PXI Express controller automatically powers on if I remove it from my chassis, clear the CMOS and re-insert it. What is happening?

 

Solution

The PXI Express controllers maintain information about the last power state and whether power was lost.  Removing a PXI Express controller such as the PXIe-8103 from a PXI Express chassis causes a power fail event to be registered.  The response of your controller to a power failure is dependent on the controller's BIOS setting "After Power Failure" under the "Advanced" tab.  When the CMOS is cleared, this BIOS setting is also cleared.  Thus, when you reinsert the controller into your chassis, it will automatically power on the first time.  

To prevent this behavior (the controller remains off when reinserted into the chassis), you can unplug your power cord before reinserting your controller into the chassis after resetting your CMOS.
 

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