News and Views

I’m on the plane returning from Gary, IN and a PROFIBUS one-day training class.  One of the attendees remarked that the class was very different from the one he took three years ago.  He was very right; the class has evolved significantly over the years as we change and add material to reflect advances in the technology and feedback from attendees.  So whether you are new to PROFIBUS and PROFINET or just need to get updated, attend a class in your area – they’re free.  You will find a schedule here.

Our third webinar is tomorrow (Thursday) and I’m still getting ready for that one.  Thankfully Hunter does all the “heavy lifting” for this one.  Not so with the one after. We’ve added a PROFINET Overview webinar that I’ll take the lead on.  For future webinars, details and registration are here… and for archived webinars here.

News in the trade press and my views follow…

I was amused by the lead sentence in an article at Control Engineering: “Networking: Safety instrumented systems for processes via fieldbus?  “The idea of using fieldbus architecture for safety devices in discrete manufacturing is well established, but so far, process plants have not had this option available.”  This is only true for process plants using FF; plants using PROFIBUS PA have had safety over a fieldbus available for many years!  And that safety technology covers both the process functions of the facility and the discrete functions of the facility.  Indeed, PROFIBUS and PROFINET provide the only safety fieldbus system that allows users to create safety logic that embraces discrete IO, process instruments, and drives.  Users have a clear choice to make: a system in the experimental stage that only applies to process instruments OR a proven system that applies to process instruments, discrete IO, and drives.

For further amusement read the great article in the Industrial Ethernet Book: “Technical Article: Performance metrics for Industrial Ethernet”.  Well, perhaps it’s not so amusing if you have chosen an Industrial Ethernet technology besides PROFINET!  It clearly shows the better performance of PROFINET over Ethernet/IP.

I do have an opinion about the concluding summary though.  (I’m sure you are surprised to see that I have an opinion.)  Part of that summary says: “Our evaluation of two common Industrial Ethernet protocols reveals that they are indeed better suited to industrial use than traditional Ethernet and perform satisfactorily in a typical manufacturing control scenario. However, performance improvements are needed, especially in the area of component time synchronisation and speed/jitter.”

The graphs show that PROFINET real-time IO has a jitter of about 100 microseconds while Ethernet/IP has a greater jitter around the target time AND frequent responses clustered at twice the target time.  Maybe responses at twice the target can be labeled as “perform satisfactorily” for some applications.  Which protocol needs the performance improvements?