Solution
With Revision C of the 651x series of DIO boards, an over-current protection circuit has been added to protect the board from over-current situations. This circuit contains a self-reseting fuse to prevent catastrophic over-current situations that could result in device damage or fire.
This fuse’s performance is related to temperature. A higher ambient temperature around the fuse will reduce the current necessary to trip the fuse. As such, a revised set of maximum current specifications have been released for the PCI- and PXI-651x series of DIO devices.
These worst-case specifications were determined by testing with all input channels turned on and the output channels at max voltage with a 100% duty cycle.