C135 PCS 7 (PCS7)
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Resolving SIMATIC Shell RT Station Not Obtainable Errors During PCS 7 OS Server Downloads

Resolving SIMATIC Shell RT Station Not Obtainable Errors During PCS 7 OS Server Downloads

In SIMATIC PCS 7, when downloading an OS Server project from the Engineering Station (ES) fails with 'RT Station not obtainable' and the target server is missing from the SIMATIC Shell network browser, the failure is caused by SIMATIC Shell binding to the wrong network adapter (e.g., Plant Bus instead of Terminal Bus), mismatched communication encryption settings, or blocked RPC broadcast ports. To resolve this, open 'SIMATIC Shell' under 'This PC' in Windows Explorer on both the ES and OS, select 'Settings', bind SIMATIC Shell to the dedicated Terminal Bus network adapter, ensure encrypted communication settings match identically across all stations, and verify both stations share the same IP subnet.

Table of Contents

Executive Summary

In SIMATIC PCS 7 distributed control systems, engineering workflows require regular project downloads from the central Engineering Station (ES) to target Operator Stations (OS Servers, OS Clients, Batch Servers, and Route Control Servers). During commissioning or following a server reboot, engineers frequently encounter a download roadblock: in SIMATIC Manager, the target OS station displays greyed-out download options, and clicking download halts with the error dialog: RT Station not obtainable.

Opening Windows File Explorer reveals that the target OS Server is missing entirely from the SIMATIC Shell network neighborhood folder. Because standard Windows network sharing (\ServerName) may still function, engineers often struggle to understand why PCS 7 cannot find the runtime station. SIMATIC Shell relies on specialized Remote Procedure Call (RPC) broadcasting, multicast discovery, and security encryption over the Terminal Bus. When a multi-homed server restarts, SIMATIC Shell can bind to the wrong physical network interface, or encrypted communication handshakes can fail. This guide provides the complete diagnostic and resolution procedure to restore SIMATIC Shell connectivity and enable OS downloads.

Architecture and Fundamental Mechanics

The SIMATIC Shell communication subsystem coordinates station discovery and project deployment across the Terminal Bus:

  1. Purpose and Mechanics of SIMATIC Shell:
    - SIMATIC Shell (SimaticShell) is an integrated Windows Explorer namespace extension and background network service (CCRemoteService.exe).
    - It handles plant station enumeration, project file deployment, redundancy status monitoring, and online project activation.
    - Station discovery operates via UDP multicast/broadcast (port 5226 and 5227) and Microsoft DCOM/RPC on port 135 over the designated Terminal Bus adapter.

  2. The Multi-Homed Adapter Binding Problem:
    - PCS 7 OS Servers and Engineering Stations are multi-homed computers featuring at least two physical network adapters:

    • Terminal Bus: Connects ES, OS Servers, and OS Clients.
    • Plant Bus: Connects OS Servers and ES to S7-400 controllers.
    • When an OS Server reboots or network adapters reset, Windows may reorder adapter initialization.
    • If SIMATIC Shell binds to the Plant Bus network interface (or a virtual VM adapter), it sends discovery broadcasts onto the controller network where the ES Terminal Bus interface cannot hear them. Consequently, the ES reports 'RT Station not obtainable'.

  3. Communication Encryption in PCS 7 V9.0 / V9.1:
    - Beginning in PCS 7 V9.0, Siemens introduced 'Encrypted Communication' within SIMATIC Shell to secure project data transfer against eavesdropping.
    - If encryption is enabled on the Engineering Station but disabled on the OS Server (or if the shared migration encryption key mismatches), the stations will fail mutual authentication and will refuse to display each other in the SIMATIC Shell browser.

Step-by-Step Implementation Procedure

Follow these steps to configure SIMATIC Shell and resolve 'RT Station not obtainable' errors:

  1. Configure Network Adapter in SIMATIC Shell on ES and OS:
    - On both the Engineering Station and the target OS Server, open Windows File Explorer (Win + E).
    - In the left navigation pane, expand 'This PC' and locate the folder named 'SIMATIC Shell'.
    - Right-click 'SIMATIC Shell' and select 'Settings...'.
    - In the SIMATIC Shell Configuration dialog, review the list of available network connections.
    - Select the network adapter physically connected to the Terminal Bus (ensure neither the Plant Bus adapter nor virtual loopback adapters are selected).

  2. Align Communication Encryption Settings:
    - In the same SIMATIC Shell Settings dialog, inspect the 'Encrypted Communication' section.
    - If encryption is used: ensure the checkbox 'Encrypted communication' is checked on BOTH the ES and the OS Server, and verify that the identical migration key / password is entered.
    - If encryption is not utilized: UNCHECK 'Encrypted communication' on both the ES and the OS Server.
    - Click 'OK'. Windows will prompt to restart the communication service; click 'Yes'.

  3. Verify IP Subnet and Network Profile:
    - Open Command Prompt and run ipconfig /all on both computers.
    - Verify that the Terminal Bus adapters of the ES and OS reside within the same IP subnet (e.g., ES: 172.16.20.10/24, OS: 172.16.20.11/24).
    - Open Windows Defender Firewall > ensure the network profile for the Terminal Bus adapter is set to 'Private' or 'Domain' (NOT 'Public', which blocks RPC multicast).

  4. Verify Station Visibility in SIMATIC Shell:
    - Open the 'SIMATIC Shell' folder on the Engineering Station.
    - Confirm that the target OS Server (Server1) appears in the station list.
    - Double-click the server icon: confirm that its hosted WinCC project name is visible.

  5. Execute OS Project Download:
    - Return to SIMATIC Manager on the Engineering Station.
    - In Component View, right-click the OS Server object and select 'PLC > Download...'.
    - The download scope dialog will now display the target server path active and accessible (no longer greyed out).
    - Select 'Entire project' (for initial download) or 'Changes only' and click 'OK'.

Verification

  1. In Windows Explorer on the ES, open SIMATIC Shell: confirm that all OS Servers, redundant standby servers, and clients appear with active status icons.
  2. In SIMATIC Manager, initiate the OS download: confirm that the transfer progress bar initializes and copies WinCC runtime project files across the Terminal Bus without error.
  3. On the OS Server, launch WinCC Explorer: confirm that the downloaded project opens cleanly and activates into Runtime.

Limitations and Operational Precautions

Never route Terminal Bus traffic through NAT firewalls or routers that strip broadcast/multicast packets without configuring a SIMATIC Shell Multicast Proxy. Ensure that the logged-on Windows user account on the ES exists on the OS Server with local administrative rights and identical passwords. System licensing and networking options should be verified through an authorized Siemens distributor or the Siemens Industry Mall.

Engineer FAQ

What causes the error 'RT Station not obtainable' during OS download?

SIMATIC Shell cannot locate the target OS station because it is bound to the wrong network adapter, encryption settings mismatch, or the stations are on different subnets.

Where do I access SIMATIC Shell settings?

In Windows File Explorer, under 'This PC > SIMATIC Shell', right-click and select 'Settings...'.

Which network adapter must be selected in SIMATIC Shell?

The network adapter dedicated to the Terminal Bus (connecting ES, OS servers, and clients).

Can I download an OS project if SIMATIC Shell does not show the server?

No. SIMATIC Shell provides the mandatory transport and authentication layer required by SIMATIC Manager to execute OS downloads.

What Windows firewall profile should be used for the Terminal Bus?

The network profile must be set to 'Private' or 'Domain'; the 'Public' profile blocks essential RPC and multicast discovery traffic.

Technical References

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Related Tags

  • SIMATIC Shell
  • RT Station Not Obtainable
  • OS Download
  • Terminal Bus
  • Encrypted Communication
  • PCS 7 V9.1
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