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Transmission technology

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PROFIBUS is used for a variety of application areas and therefore makes use of different transmission technologies. PROFIBUS DP and PROFIBUS FMS both use RS 485 transmission. In addition, optical transmission via glass or synthetic fibre optical cable (FOC) can be used. PROFIBUS PA uses a special transmission technology known as MBP (= Manchester bus powered) that also allows field devices to be supplied via the bus. RS 485-IS and MBP-IS are two versions with intrinsically safe transmission.


A type is defined for the transmission technology. In IEC 61784 the following types have been defined for PROFIBUS:


Type designation

Transmission technology


copper cable with RS 485


synchronous MBP


synthetic FOC


glass FOC




In the electronic data sheet, the GSD file, the transmission technology is defined under the key word Physical_Interface. If this key word is not used in the GSD, only one RS485 port is offered. Other interfaces can be indicated with the values set out in the above table. In addition, driver delay times can be specified:


Physical-Interface = 1                     ; synchronous MBP

Transmission_Delay_31.25 = 0

Reaction_Delay_31.25     = 0



Couplers, links and FO converters are available for making the transition between different transmission technologies. Whereas couplers and converters implement the protocol transparently taking account of physical conditions, links have their own intelligence and therefore offer extended possibilities for the configuration of PROFIBUS networks.


As an aid to getting started, there is also web-based training (WBT) for PROFIBUS installation technology.