Foundation Fieldbus device communication establishment process explained for the layperson

Hello. I am trying to interpret some data from an FF-H1 installation in which some FF-H1 devices experience very irregular behaviour in that the host issues communication alarms due to lack of communication from the devices in question, but without any pattern, completely randomly.

A similar environment (similar power conditioner, junction box, FF-H1 devices but different host) has been setup (at a laboratory, different from the actual refinery) in which there is FF Bus Monitor available, but since I do not have the FF Bus Monitor software I am relying in a text file that has some four million lines, not so easy to analyze.

I have verified that the power conditioners, junction boxes, cable and termination are all standard product from recognized manufacturer, and the total of devices per segment is well below (less than half) the maximum current provided by the power conditioner. Cable lengths are a few tenths of meters, so poor noise is something that at this moment I am not giving a high probability (nut have not completely ruled out).

It seems from the traces that the device in question is for some reason restarting.
I am reading through the FF specification of which I am not so familiar and I wonder if anyone is literate enough in FF specification so as to guide me to the correct spot in the specification which explains that an FF-H1 basic device is supposed to do after powering on and receiving from the link master the PT (pass token) request, so that I may be able to confirm or reject my hypothesis that the device is re-initializing. Or if there is any paper or article that discusses this kind of issues at some depth, that would also help. Thanks.


Hello, it is an interesting case study.

What is your end result?

Can you please share with us?