Emerson Exchange 365

Standalone SIS v12

Is there any information on how to connect the temporary Proplus to the Primary Modbus port IP address? We are unable to find any specific information in BOL or Guardian. It obviously connected years ago when the system was first deployed because the SZ controllers were commissioned at that time.  The temporary Proplus  IP address is set to 10.4.0.6, 255.255.2.0. The Modbus address is set to 167.151.x.x, 255.255.255.0. The system still is V12. Should it still be possible to connect the temporary Proplus to the Primary port since the Modbus address was changed. In v12 there is no way to set the primary and secondary Modbus port separately. An upgrade to 15 is being considered. Is the connection method different with v13 and up? 

Russell E Smith

• 14 Jan 2026 4:09 PM
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4 Replies

• Mark Flores

  

  • 16 Jan 2026 8:14 AM

  I haven't tried this setup. Typically, if this is not publish on BOL or KBA, this is not supported. Why do you want to connect your old Proplus to the MODBUS network if i may ask?

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• Russell E Smith

  

  • 16 Jan 2026 1:47 PM

  In reply to Mark Flores:

  I found a DeltaV SIS Standalone Whitepaper dated June 2020. The existing Standalone SIS system has been running for nearly 10 years. The issue has been that Modbus communication connected to the secondary ACN/Modbus port frequently locks up and that data goes stale. A redundancy switchover has been the recovery work around. The Proplus is a Toughbook laptop and may be temporarily connected to the Primary port for configuration, commissioning, flashing, downloading, etc. In V12 Modbus on SZ controller was simplex and must be connected to the secondary port. It is my understanding that Modbus ports are redundant since v13. We are trying to find out if the Standalone SIS with the redundant Modbus communication in v15 is a proven architecture. The white paper shows the top ports of the isolated ethernet parts are Redundant Modbus/TCP. In BOL show them as both ACN and Modbus. Hopefully this information helps to clarify my question - Can both Modbus ports be enabled for redundant Modbus while still being able to connect the Proplus? Or should only the secondary Modbus port be enabled for a Standalone SIS node, thus negating any opportunity to utilize the Modbus redundancy feature in the later versions?

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• Andre Dicaire

  

  • 16 Jan 2026 4:08 PM

  In reply to Russell E Smith:

  Yes, this is a proven architecture. Both ACN DeltaV traffic and ModbusTCP traffic co-exist on the same physical port.
  
  The ACN RJ45 ports of the SZ controller also serve as the Modbus ports by design. The SZ ethernet ports are configured with two IP addresses on different subnet masks. A switch will locate the connected ports for the Pro Plus and ModbusTCP client and communications will be passed accordingly. Depending on your cybersecurity risk tolerance and network design, you may choose to add a firewall to limit traffic flow, including keeping DeltaV ACN traffic on the DeltaV SIS side, and allow only valid ModbusTCP traffic between the SZ and the Client.
  
  As of v13, the Modbus TCP connection can be redundant, with primary defined typically to align with DeltaV ACN usage, that is primary network on the left, Secondary on the right.

  Andre Dicaire

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• Russell E Smith

  

  • 22 Jan 2026 3:54 PM

  In reply to Andre Dicaire:

  Thank you for your knowledgeable reply!
  A follow-up question came up regarding redundancy switchover. We are able to do a forced switchover but cannot switchover within diagnostics with the Proplus connected to the primary port. Diagnostics shows bad redundancy due to no primary ACN communication, but always and only the standby controller. When a forced switchover is done the bad communication is always with whichever controller is the standby. The Active controller primary connection remains healthy. Is this expected behavior for a standby SIS architecture in V12? Will v15 make it possible to switchover within diagnostics?

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