I would like to know the difference between Profisafe and Profibus. I have researched many web sites but most of them are in German. I cannot read them. In one of them I saw a picture of the many layers of a protocol stack and Profisafe was on top of Profibus. So, may I say Profisafe is one layer in Profibus protocol ? What is the main purpose of the Profisafe ?

 

As far as I can tell, Profisafe is a safer version of Profibus, intended to run on the same bus, using the same hardware, for Safety devices/applications. As far as I know, so far, SP 84.01 and similar standards say you should not use any busses for interconnecting either sensors or final elements to your "logic box". This may be revised soon, but that is what is written now. For other applications then "wet process" and similar (where SP-84 is intended to be used) , such as in mechanical machinery, discrete parts manufacturing, etc, there are already "safe busses" for field devices and special safety relays and other devices in use for many years. This is everyday common technology for them. There are even manufacturers specialized in those applications. I guess Safety in Manufacture usually means to avoid crushing a press operator's arm, while in the Chemical Industry it might mean to avoid accidents such as in Bhopal, where many thousands of local inhabitants have lost their life, while so many are still suffering for the rest of their lives the consequences of the event. Different risks ask for different criteria for designing the Safety Instrumented System, IMHO, Vitor Finkel P.S. I think I saw an article written by someone from Siemens (in English) about profisafe. Why don't you try to contact a Siemens representative ?

 

Isn't Profisafe the vault that the Profibus spec is kept in? Sorry, I couldn't resist.

 

>I would like to know the difference between Profisafe and Profibus. >I have researched many web sites but most of them are in German. I cannot >read them. In one of them I saw a picture of the many layers of a protocol >stack and Profisafe was on top of Profibus. So, may I say Profisafe is one >layer in Profibus protocol ? Technically: yes. It uses standard DP, but part of the datafield of a message is used for Profisafe bookkeeping, so as to comply with the strict German rules regarding all sorts of unusual events that can take place on a network and prevent the correct behaviour of Profisafe in the case it is needed. For example, the Profisafe datafield has an own CRC, because you can't rely on the simple DP checksum for detecting transmission errors. >What is the main purpose of the Profisafe ? Safety applications. A book (in German) about this and how industrial networks can be used for it is due soon. Rob

 

PROFIsafe is a Profibus profile specific to safety instrumented system applications (other profiles include PROFIdrive, for drive control). A profile is an additional set of communication protocols defining the contents of messages. PROFIsafe was developed to allow communication between a safety PLC and field instruments. The protocol was developed to detect the dangerous and nuisance faults that can negatively impact performance of a SIS. I believe that the PROFIsafe protocol has been TUV certified for SIL 3 applications against IEC 61508, but a quick check of the TUV Product Service web site was not fruitful. If you wish to get more information on PROFIsafe, you should contact Tim Parmer, who is responsible for Marketing of Siemens safety critical equipment in the US. [email protected] Best Regards, Edward M. Marszal, PE, CFSE Principal Engineer, Exida Ph: 614-226-4263 Fax: 614-459-9764 e-mail: [email protected] http://www.exida.com Vitor Finkel wrote: > As far as I can tell, Profisafe is a safer version of Profibus, intended to run on the same bus, using the same hardware, for Safety devices/applications. .... <