Question
The MBP (Manchester Bus Powered) physical layer of PROFIBUS PA uses Manchester coding at 31.25 kbps on an intrinsically safe twisted pair, supporting up to 32 devices per segment and a maximum length of 1 900 m.
PROFIBUSMock examPROFIBUS PAHard
Answer
True
Key MBP specifications (IEC 61158-2) are: Manchester coding, 31.25 kbps (slow but sufficient for process transmitters), 9-32 V DC carried on the bus, up to 32 devices per segment (in practice 8-16 in Ex ia zones), up to 1 900 m of cable, Ex ia / ib classification for intrinsic safety in gas or dust zones, and a typical current draw of around 10 mA per transmitter. A DP/PA Coupler bridges the segment to the higher-speed PROFIBUS DP RS-485 backbone.
Preparation tip
Always derate device count and length for Ex ia segments: the standard headline figures (32 devices, 1 900 m) assume a non-Ex installation.
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