As far as I can tell:
The DataPower power supply does have a "Power OK" signal on pin 21 (Labeled "/Power Fail" on the schematic.)
You measure +5 on the pin when the Widget is attached because it is pulled up to +5 by R1 on the Widget.
You measure 0V on the pin when the Widget is not attached because it is not driven by the power supply (it is an open collector output that can only sink current).
This signal doesn't go to the motherboard.
I suppose the simplest approach is to leave the pin unconnected and the Widget will pull it high.
HTH, James
-- --
This archive was generated by hypermail 2.4.0 : 2020-01-13 12:15:17 EST