As Amibroker base time interval confined to 5-sec, 15-sec only, does it mean that no other sec periodicity could be backtested?
If you enquire about custom periodicity, you should start from searching the forum for custom periodicity.
A similar question has already been answered:
Amibroker base time interval is not confined to 5-sec or 15-sec only! You should choose 1 Second as Base time interval if you want to select 42 sec periodicity in Backtester's settings.