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That does seem like a lot of ripple (nearly 2V)
that should not directly cause an issue but its
odd.

Probably the card should be returned for evaluation/repair/replacement

 One other clue might be to look at the analog input hal pins.
They should be very close to 0V with nothing connected.

The way the 7I76U digital inputs work is that they are read as
analog voltages and the threshold/hysteresis is set by the
field voltage. That's why I suspected a field voltage sensing issue.
 

I'm using a dedicated 24v switching power supply which is holding a constant 24.1 output. Setting the sserial_port_0=20xxxxxx and reading the fieldvoltage I'm seeing a constantly fluctuating value from 22.01 - 23.9 v