Issue:
What is INF6 Fault on Altivar 61 & 71 Drives?

Product Line:
Altivar ATV61 and ATV71

Environment:
All products

Cause:
The control terminal card may be loose or there may be 2 serial communication cards installed at once.

Resolution:
INF6 is an internal option fault.  Basically, the option card installed on the VFD is not recognized.
First, re-seat the control terminal card.  Then, check the 1.11 Identification menu for option 1 and option 2 to see if there are 2 conflicting option cards installed.