Emerson Exchange 365

Profibus Signal

Hi, we are connecting a new profibus DP network to an S-series card, running DeltaV 14.3.1.

We've had a number of issues with the DeltaV cards going into ERROR (RED LED flashing) and DeltaV Diagnostics saying the profibus cards are missing. The errors all seem to be caused by the field profibus cables. Could someone with profibus experience have a look at the below images of the profibus signal and give me any advice? is it within normal tolerances?

Using our PBQone Profibus diagnostic kit, its the Master (DeltaV card) which is introducing all the high spikes and noise but only since added certain slaves.

 

• Profibus
• DeltaV

Stuart Jolley

• 28 Sep 2021 4:46 PM
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5 Replies

• MICHAEL BRANNON

  

  • 28 Sep 2021 6:31 PM

  In just looking at the Topology depicted I'm not sure that this will work. Typically you have an OLM that will manage the break point for redundancy. Only Two resistors should be turned on, one at each end. Any time a Profibus card cannot communicate with one of it's slaves it will show red light on the card.

  Mike Brannon // Project Manager
  Revere Control Systems
  
  

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• mirkotc

  

  • 28 Sep 2021 6:50 PM

  In reply to MICHAEL BRANNON:

  Profibus DP does not support ring topologies using the RS485 physical layer. The diagnostic tool is showing a signal typical from a missing terminator.
  If you require a ring topology, you will have to use optical link modules (OLM) to create a ring using fiber optic cable.

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• MICHAEL BRANNON

  

  • 28 Sep 2021 7:10 PM

  In reply to mirkotc:

  mirkotc I agree. He is not going to be able to achieve redundancy with the topology and devices that he currently has.

  Mike Brannon // Project Manager
  Revere Control Systems
  
  

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• mirkotc

  

  • 29 Sep 2021 1:02 AM

  In reply to MICHAEL BRANNON:

  Nope, he won't. Profibus DP redundant masters work in combination with:
  1.- Redundant Profibus DP slaves, like in an RIO system with redundant head stations, each head station connected to a different master.
  2.- Non-redundant Profibus DP, connected via a Y-Link (available either from Siemens or ABB), a device that allows the connection of a non-redundant DP slave to dual Profibus DP lines.
  
  To implement a ring topology, it is necessary to connect the masters to a redundant OLM via copper (RS-485) and then connect the required slaves to a copper drop via another OLM.
  An additional benefit of a FO ring is that, since it provides a galvanically isolated connection between the master and the slave, it is no longer necessary to have a common ground connection for the master and the slaves connected to the copper drop of the FO ring.

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• Stuart Jolley

  

  • 29 Sep 2021 4:46 PM

  Thanks All, we are going to re-wire the network to give us the required daisy chain segment.

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