C135 PCS 7 (PCS7)
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Configuring OS Single Station Redundancy and Verifying Archive Synchronization in PCS 7

Configuring OS Single Station Redundancy and Verifying Archive Synchronization in PCS 7

In SIMATIC PCS 7, configuring OS Single Station Redundancy requires deploying exactly two physical operator PCs that both run standalone WinCC projects linked to the same S7-400 automation controllers. In runtime, both stations acquire process data independently; if one station fails, the WinCC Redundancy software agent automatically synchronizes missing Alarm Logging messages, Tag Logging historical archives, and User Archives across the redundancy link upon recovery. Crucially, OS Clients cannot connect to an OS Single Station redundant pair. To license this topology in PCS 7 V9.0, order package 6ES7652-3AA58-2YA0 (PO 100) and SIMATIC NET S7-REDCONNECT for redundant controller communication.

Table of Contents

Executive Summary

Small to medium process installations often require high supervisory availability without the expense and space requirements of a full client-server server farm. SIMATIC PCS 7 satisfies this need through OS Single Station Redundancy, pairing two standalone operator stations that independently poll the plant controllers while maintaining synchronized historical alarm and trend archives. However, engineers frequently misunderstand the boundaries of data synchronization—mistakenly expecting offline files or uncommitted setpoints to transfer—and encounter severe architectural roadblocks when attempting to attach operator clients. This article outlines the step-by-step engineering configuration in SIMATIC Manager, explains the underlying WinCC Redundancy synchronization engine, and clarifies licensing requirements.

Architecture and Fundamental Mechanics

OS Single Station Redundancy Topology, Synchronization Scope, and Client Isolation Mechanics:

  • Architecture of OS Single Station Redundancy:
  • Consists of two independent PC stations (OS Single Station A and OS Single Station B).
  • Each station runs a complete, standalone WinCC runtime project containing graphics, scripts, tag logging, and alarm logging.
  • Both stations connect directly to the Plant Bus (Industrial Ethernet) and communicate in parallel with the S7-400 controllers.

  • An operator can execute commands and view alarms from either station at any time.

  • The Precise Scope of 'Data Synchronization':

  • In steady-state operation, both stations receive process telegrams and log events simultaneously.
  • When Station A shuts down for maintenance or experiences a network disconnection:
    • Station B continues operating and logging data independently, flagging the failure of its redundant partner.
    • When Station A reboots, the WinCC Redundancy background agent (CCRedCom.exe) detects the return of Partner A.
    • The synchronization agent compares SQL message and archive timestamps, extracts the gap from Station B's database, and copies all missing Alarm Logging records, Tag Logging Fast/Slow values, and User Archive rows into Station A.

  • What is NOT synchronized:

    • Uncommitted operator inputs on screens.
    • Local internal non-retentive tags.
    • Offline project files or graphic modifications (all project changes must originate from the central Engineering Station).

  • The Client Connectivity Constraint:

  • OS Single Stations do not generate server data packages (.pck) for standard PCS 7 OS Clients.

  • Therefore, standard OS Clients cannot connect to an OS Single Station pair. If a plant requires 3 or more operator screens, an OS Server Redundancy architecture must be selected instead.

  • Software Licensing Analysis:

  • Package 6ES7652-3AA58-2YA0 (SIMATIC PCS 7 OS Single Station Redundancy V9.0, 100 PO) licenses both Single Stations and includes WinCC Redundancy.
  • If connecting to redundant S7-400H CPUs via CP 1623 cards (6GK1162-3AA00), each PC requires SIMATIC NET S7-REDCONNECT (6GK1716-0HB14-0AC0).

Step-by-Step Implementation Procedure

  1. Configure PC Stations in SIMATIC Manager:
    * In Component View, insert two PC Stations: OS_Single_A and OS_Single_B.
    * In HW Config for each station, insert the Industrial Ethernet network card (CP 1623 or IE General) and a WinCC Application.
    * Save and compile hardware configuration for both stations.

  2. Establish the Redundant Relationship:
    * In SIMATIC Manager, select OS_Single_A.
    * Open the object properties of the OS project.
    * Select OS_Single_B as the redundant partner station.
    * SIMATIC Manager automatically synchronizes the project structure across both stations.

  3. Configure WinCC Redundancy Editor:
    * Open WinCC Explorer on the master station.
    * In the navigation tree, double-click Redundancy.
    * Check Activate Redundancy.
    * Select the redundant partner computer name.
    * Specify the dedicated network connection for redundancy synchronization (e.g. redundant LAN or terminal bus adapter).
    * Check 'Synchronization of all archives after failure' (Alarm Logging, Tag Logging, User Archives).
    * Click OK and compile OS changes.

  4. Deploy and Verify via Automation License Manager:
    * Install the Single Station Redundancy license keys on Station A and Station B.
    * Download the OS project to Station A and Station B from the Engineering Station.

Verification

  1. Start WinCC Runtime on Station A and Station B.
  2. In WinCC Explorer, verify that the internal system tag @RedundancyState reads 1 (Master) on one PC and 2 (Standby) on the other.
  3. Disconnect Station B's network connection for 15 minutes while generating process alarms in the plant.
  4. Reconnect Station B; verify that @RedundancyState changes to 3 (Synchronizing) and subsequently returns to 2.
  5. Open Alarm Logging on Station B; confirm that all alarms that occurred during the 15-minute outage have been fully restored.

Limitations and Operational Precautions

Under no circumstances should engineers attempt to connect standard WinCC OS Clients to an OS Single Station redundant pair. Data synchronization bandwidth depends on network capacity; ensure the redundancy network link has sufficient throughput to prevent CPU throttling during large archive catch-up operations. Final procurement packages should be verified with an authorized Siemens distributor.

Engineer FAQ

What does WinCC Redundancy synchronize on Single Stations?

It synchronizes Alarm Logging messages, Tag Logging historical process data, and User Archives following an interruption.

Can I connect an OS Client to a redundant Single Station pair?

No. OS Clients require an OS Server architecture. Single Stations cannot serve standard OS Clients.

Does one license package cover both single stations?

Yes, the Siemens OS Single Station Redundancy package (6ES7652-3AA...) includes software licenses for both PCs in the pair.

Why is S7-REDCONNECT needed for CP 1623?

S7-REDCONNECT is mandatory to manage fault-tolerant S7 communication over Industrial Ethernet when communicating with redundant S7-400H CPUs.

What internal tag shows redundancy synchronization status?

The @RedundancyState internal tag: 1 = Master, 2 = Standby, 3 = Synchronizing, 4 = Faulted.

Technical References

Related Articles

Related Tags

  • Single Station Redundancy
  • WinCC Redundancy
  • Data Synchronization
  • CP 1623
  • S7-REDCONNECT
  • Process Objects
  • PCS 7 V9.0
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