Problem with Siemens Fieldbus positioners

We are facing with some serious problem using our newly purchased Fieldbus Siemens positioners SIPART PS2 FF (N1-A413-7519177; **SIPART PS2 FF**, revision name:2.0 ; DEV_REV: 0X02; DD_REV: 0X01) in our control system which is Yokogawa's CS3000 R.3.08.50.

We assign the positioners to the segment and they will be assigned and work without any problem, but after several hours (or even days) we lose the communication with the control valves and the face plates in the control system change to CNF (connection failure). We then have to disconnect and re-connect the positioners' cable to put it again into work.

The problem is happening for nearly all Siemens positioners and the positioners are all new. The segments are having 8 Fieldbus instruments, two of which are Siemens positioners. When the Siemens positioners become faulty, all other instruments continue working properly.

We have replaced the faulty positioners with another brand (ABB), it works without any problem. Does anybody know what is the problem and how we can solve it?
I asked Siemens for support but they just told me to contact Yokogawa about this problem! The problem with Siemens positioners is still here. We have Samson and ABB FF positioners working properly but Siemens has problem.

Curt Wuollet

I would strongly suspect a wiring problem. Not the obvious type. I would put a DSO (digital storage oscilloscope) on the bus. I have found several of these.

"now you see it now you don't" type problems to be due to signal integrity. Most differential systems will work even with one wire shorted, but with much reduced noise margin, etc. The last one was a new system where the VFDs would go offline. When I looked, one wire was a constant zero volts. There is a differential, it's just half of what it should be. So, stuff will work when it feels like it but a small change of some sort and it won't. Once I knew this I told the guys it was probably a short. They found where stripping the jacket had nicked a signal wire and pushed the shield foil into the nick. Reterminated and it has been working flawlessly since. The moral is: don't assume because it works part of the time, that the wiring is good. That one cost many days and dollars of vendor guessing, but only about an hour after I scoped the signals and knew what to look for. And someone with an ohmmeter could have found it while installing.

Thank you sir, but this is the problem we have on nearly all segments having more than one Siemens positioners on them. as I said before, when we replace these faulty Siemens positioners with that of ABB or Samson on the same segment, the problem will go.

I suspect that JDPS2 works for Siemens because he writes, "we'll get this resolved immediately". We = Siemens

At one time or another, all of us have run into the unfortunate situation of the blame game - finger pointing at another party, but you now have the manufacturer's attention, so it's up to you to take Siemens up on their offer of support because he can't contact you, you need to contact him through the link he and another poster provided.

Siemens is in the best position to support you - they're the ones with the widest knowledge base.
Hi David_2

I did it but they simply told me to ask Yokogawa. while I think this is their problem as ABB and Samson positioners on the same segment are working properly.
Hi David_2

depending on the country you are from, big companies like Siemens is not allowed to support you.

But they have sold many many of their products to us recently!

Moreover, this is just a technical issue about possible inconsistency of their positioners when being compared to other brands like ABB or Samson. They should be willing to know about the problem to increase their knowledge and apply it in their future releases. This problem can serve them as a valuable feedback, and we surely keep in memory their act of support these times when the embargoes are lifted to adjust our vendor list.
The Siemens positioner's problem is not solved and we have to replace all of them. I have asked my colleagues not to use it in any of their projects anymore.
DEAR MR. Hasseli,

We are faced with the same problem here with Siemens positioners as the control system is Yokohama CS3000. Thank you for explaining the issue and letting us know.

Best wishes,