PROFIBUS Manual

The bus connection for MBP segments has the same function as described for RS 485: the prevention of reflections. With MBP, however, bus termination has a completely different structure compared with RS 485 bus termination. An MBP bus termination consists of resistance and capacitance switched in series between the two conductors:  

MBP bus termination

This termination is passive and has no special need for a power supply. Bus termination must only be applied to the main line and not the individual stub lines.  Most segment couplers have built-in bus terminations, which should therefore be on the last or furthest distant field device, or in the last junction box or branch socket.

Combination of line and stubs to build a tree structure