Hej Erik

Even if your bus shakes, rattle and rolls, it gues that a relay could be used. Try Pickering - they used to be the ones making "the" small signal relays.

Combat aircrafts do include relays - dont they?

Another way of "autoterminating" could be forcing the service guys to plug in the terminator. If your device has to identical connectors, with the PSU line - or a control line - wired thrugh them both in series, nothing would work without either a terminating plug or a wire for the next unit on the bus.(!) You could even mount a red led for flashing the error condition.

God arbejslyst

Per Guldmann