Profinet vs Profibus

Hello automation experts,

I know that Profibus was preferred communication much before Industrial Ethernet (Profinet), at least with Siemens.
I wonder why is that, since ethernet based networks existed for long time.It seems that only in last 10 years Profinet started to dominate the market.

Old OP panels (20 years old or so) had only Profibus port. What were disadvantages of Profinet comparing to Profibus that enabled PB to dominate such number of years?

Thank you.

Adenitz said:

Hello automation experts,

I know that Profibus was preferred communication much before Industrial Ethernet (Profinet), at least with Siemens.
I wonder why is that, since ethernet based networks existed for long time.It seems that only in last 10 years Profinet started to dominate the market.

Old OP panels (20 years old or so) had only Profibus port. What were disadvantages of Profinet comparing to Profibus that enabled PB to dominate such number of years?

Thank you.

Click to expand...

Profinet is relatively new.

Main default of Ethernet was that it is not deterministic because of packets collisions.

Large Siemens PCS7 systems, often have redundant Profibus networks. Profinet has only been redundant capable for a short time.

The rest of the answers are pretty good, but you also have distance. Profibus can be used with large distances whilst Profinet requires fiber optics after 80 to 100 meters.



Fiber is expensive and not everyone was willing to put the money to use it.



Profinet is also not used in hazardous areas, where Profibus can be used... so there's that as well, although it is a very reduced area of application.

Adenitz said:

What were disadvantages of Profinet comparing to Profibus that enabled PB to dominate such number of years?

Click to expand...

The main answer here is that Profinet wasn't released until something like 2004. Profibus had (still has) a huge install base, and it took a while for the advantages of the new standard to outweigh the problems involved with switching.



Also, keep in mind that there were a lot of roadbumps in early Ethernet, things like needing separate patch vs crossover cables for connecting devices of different types, using hubs instead of (expensive) switches, etc. Ethernet is so much friendlier now than it was back then.

cardosocea said:

The rest of the answers are pretty good, but you also have distance. Profibus can be used with large distances whilst Profinet requires fiber optics after 80 to 100 meters.

Fiber is expensive and not everyone was willing to put the money to use it.

Profinet is also not used in hazardous areas, where Profibus can be used... so there's that as well, although it is a very reduced area of application.

Click to expand...

These are the main situations still seen where DP still has some advantages.


Also, I haven't seen any CPUs that support FULL redundancy (dual networks, running from dual CPUs to each IO rack have dual network connections). The only PN redundancy I've seen uses a network ring; it's pretty good, but doesn't cover all use cases. That said, it's a niche within a niche.