At a 3500's slot configuration, both semi-slots has two channels. Now I can't remember well, but there are two items in Options: princ. and backup, for both semi-slots. And I should choose either channel 1 or channel 2 for each one. I mean, first semi-slot: princ. = ch 01 or ch 02 - backup ch 01 or ch 02, 2nd semi-slot: princ. = ch 01 or ch 02 - backup ch 01 or ch 02
What happens if I choose ch 02 for prin. AND backup in a semi-slot?
The alarm of ch 01 and the alarm of ch 02 are in a AND alarm logic.

Thanks and sorry about anything.

 

I think you are talking about Keyphasors.
The main principle behind the primary and backup (secondary) is that if primary keyphasor channel fails then the backup keyphasor channel takes over and you can make any keyphasor channel primary and any other keyphasor channel as secondary.

If anything is not clear please tell me.