There are two connectors:  the two classics - P1 and P2 - and the DB62F. Whatever is connected there is the user wish:  either the tape drive or the pertec controller. To keep things simple, these two are not supposed to be online at the same time. If acting as a host, only the drive itself should be tunrned on. If acting as a drive, the tape drive should be switched off. You got the idea.