I currently try to understand a new technology: Profibus, until now I worked with HART, with which I also had some struggle in the begging but now it's clear. I try to understand why in a factory is used both PA and DP. I understand that to convert a PA Profibus to DP a coupler is needed "...The connection of PROFIBUS PA subsegments to the RS-485 PROFIBUS DP segment is carried out using segment couplers or links. Segment couplers are transparent from the standpoint of the bus protocol...", but what I don't understand is why the PA is used? and not directly DP? (only for safety reasons? "... PROFIBUS PA can be deployed in hazardous environments since its physical layer: MBP, is intrinsically safe..." in this case what does it mean intrinsically safe?)

And what is the difference between these terms:

  1. PA (process automation)
  2. DP (decentralized periferics)
  3. MBP and RS485

I understand that MBP and RS485 are the communication protocols, but in this case what are PA and DP? Only a standard (e.g ISO)?

  • \$\begingroup\$ I am having the same understanding problem. is it a complete bus system or just I/O peripherie? \$\endgroup\$
    – alfonso
    Aug 9, 2022 at 10:30


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