Are you using the comm port on the processor itself or a separate 1756-EN* card?
I'm not sure this is correct.
My understanding is that the main issue with AOI tag types being read is the EnableIn/EnableOut tags are locked to "Hidden" from external access and can not be changed from that.
Edit: This was not correct, but the link is still pertinent to the conversation.
I believe these two things are contradictory unless you're going to pull some big plugs for @pturmel