C135 PCS 7 (PCS7)
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Resolving WinCC Error Cannot Open User Archive During CEMAT Online Trend Saving on OS Clients

Resolving WinCC Error Cannot Open User Archive During CEMAT Online Trend Saving on OS Clients

In SIMATIC PCS 7 systems running CEMAT, the error 'cannot open user archive' when saving online trend groups on OS Clients occurs because the OS Client is attempting to access the User Archive database locally rather than routing the request to the central OS Server. To resolve this: 1) In WinCC Explorer on the OS Client, open Server Data and assign the active OS Server as the 'Standard Server' for User Archives and Split Screen Manager; 2) Ensure the User Archive server package (*.pck) has been generated on the OS Server and loaded on the client; and 3) Verify that the logged-in Windows user and WinCC operator account possess explicit User Archive read/write permissions (Authorization Level 1000 or custom privilege) across the network.

Table of Contents

Executive Summary

In cement and mineral processing facilities automated with SIMATIC PCS 7 and CEMAT, operator workstations rely heavily on CEMAT Online Trends to monitor real-time kiln temperatures, ball mill vibration, and feeder throughput. While engineers and operators can create, modify, and save trend curve archives seamlessly on the OS Servers and Engineering Station, attempts to save new trend archives from OS Clients frequently fail with the diagnostic message 'cannot open user archive'. This issue stems from the distributed architecture of WinCC User Archives in a multi-client environment, where clients lack local database storage and must be explicitly configured to direct User Archive transactions to the central redundant OS Server pair. This technical guide outlines the client-server database architecture and provides the exact procedure to restore online trend saving.

Architecture and Fundamental Mechanics

CEMAT User Archive and Multi-Client Architecture

CEMAT utilizes the WinCC User Archive option to persist runtime trend configurations (pen colors, tag assignments, time scales, and group layouts) into SQL Server database tables (C_TREND or UA_C_TREND).

+-------------------------------------------------------------------------+
|                         OS Client Workstation                           |
|                                                                         |
|   [Operator edits CEMAT Trend Page -> Clicks 'Save Archive']            |
|                                   |                                     |
|                                   v                                     |
|   +-----------------------------------------------------------------+   |
|   | WinCC Client Runtime: Where to save User Archive?                |   |
|   |                                                                 |   |
|   | IF Standard Server for User Archives is NOT CONFIGURED:         |   |
|   | -> Tries local SQL database -> FAILS: 'Cannot open user archive'|   |
|   |                                                                 |   |
|   | IF Standard Server IS CONFIGURED:                               |   |
|   | -> Routes SQL insert via Named Network Connection to OS Server  |   |
|   +-----------------------------------------------------------------+   |
+-----------------------------------|-------------------------------------+
                                    | Routed SQL Transaction
                                    v
+-------------------------------------------------------------------------+
|                    WinCC OS Server (Central Database)                   |
|                                                                         |
|   - WinCC Project SQL Instance                                          |
|   - User Archive Table: 'C_TREND' / 'UA_C_TREND'                        |
|   - Windows Share Access: SIMATIC HMI Group / DCOM Security             |
+-------------------------------------------------------------------------+

Root Causes for Client Access Rejection

  1. Missing Standard Server Assignment: Unlike process pictures that load via server packages, User Archive read/write operations from a multi-client require an explicit pointer to designate which OS server hosts the central archive table.
  2. Outdated Server Data Packages: If server data (<ProjectName>.pck) was not regenerated after creating or modifying User Archive tables, the client lacks schema metadata.
  3. Network and Security Restrictions: When clients run on Windows 7 and servers on Windows Server 2016, SMB protocol negotiation (SMBv2/v3 signing) or missing membership in the server's SIMATIC HMI Windows group blocks remote SQL DCOM calls.

Step-by-Step Implementation Procedure

Step 1: Assign Standard Server for User Archives on OS Client

  1. On the Engineering Station, open the OS Client project in WinCC Explorer (or open WinCC Explorer directly on the OS Client in standalone mode).
  2. In the WinCC navigation tree, right-click Server Data and select Standard Server....
  3. In the Standard Server dialog, locate the component list:
    - Locate User Archive (or Benutzerarchive).
    - Click the dropdown in the Server column and select your primary OS Server (e.g., OS_SRV_PRJ::Server1).
    - Also verify that Split Screen Manager is assigned to the primary OS Server.
  4. Click OK to commit the standard server assignment.

Step 2: Regenerate and Update Server Data Packages

  1. On the Engineering Station, select the master OS Server project.
  2. In SIMATIC Manager or WinCC Explorer, right-click Server Data and select Generate....
  3. After generation completes, open the OS Client project.
  4. In WinCC Explorer, right-click Server Data > Update... or select Load... and re-import the updated .pck package from the OS Server.

Step 3: Verify User Authorization in WinCC User Administrator

  1. In WinCC Explorer on the OS Server, open User Administrator.
  2. Select the operator user group assigned to client users.
  3. Verify that the group has authorization enabled for User Archives (typically Authorization Level 1000 or custom level designated for CEMAT trend configuration).
  4. Save User Administrator settings and deploy to runtime.

Step 4: Verify Windows Security and Group Membership

  1. On the OS Server machine (Windows Server 2016), open Computer Management > Local Users and Groups > Groups.
  2. Open properties for the group SIMATIC HMI.
  3. Ensure that the OS Client machine accounts and client domain users are explicit members of SIMATIC HMI.
  4. Verify that the Windows share permissions on the WinCC project directory grant Full Control to SIMATIC HMI.

Verification

  1. Client Trend Save Test: On the OS Client, launch WinCC Runtime and open a CEMAT process picture. Open the CEMAT Online Trend window, add three process analog tags, and click Save Archive under a new name (e.g., TEST_TREND_01). Confirm that the archive saves without error dialogs.
  2. Multi-Station Recall: Open the CEMAT Online Trend window on a second OS Client or the OS Server. Load TEST_TREND_01 from the archive list and verify that the saved trend curves and pens display immediately.
  3. Diagnostic Log Check: Open WinCC_Sys_01.log on the client. Verify that no SQL connection timeouts or DCOM error codes (e.g., 0x80070005 Access Denied) are recorded.

Limitations and Operational Precautions

  1. Redundant Server Synchronization: User Archive changes made from OS Clients are written to the master OS Server; verify that WinCC Redundancy synchronization is active so archive tables mirror to the standby partner.
  2. License Prerequisite: The OS Server must have a valid WinCC / User Archives license installed in Automation License Manager. Validate license keys and part numbers with an authorized Siemens distributor or the Siemens Industry Mall.

Engineer FAQ

Why does 'cannot open user archive' appear only on clients?

Because clients do not hold local database tables; they require an assigned Standard Server to route User Archive transactions over the network.

Where is the Standard Server setting located?

In WinCC Explorer on the client, right-click 'Server Data' in the left project tree and choose 'Standard Server...'.

What authorization level is needed for CEMAT User Archives?

Standard CEMAT trend archiving requires Authorization Level 1000 or the custom user level configured under CEMAT OS Engineering.

Does assigning a standard server require restarting Runtime?

Yes, the OS Client project should be deactivated and reactivated to apply new standard server communication paths.

What file stores the server metadata on the client?

The server data package file with extension .pck generated on the OS Server.

Can Windows 7 clients communicate with Windows Server 2016 for User Archives?

Yes, provided network credentials match, the client is in the SIMATIC HMI group, and SMBv2/v3 communication is permitted.

What happens if the primary OS server fails in a redundant pair?

If properly configured with WinCC Redundancy, the standard server automatically switches over to the redundant partner.

How do I verify if User Archives option is licensed?

Check Automation License Manager (ALM) on the OS Server for a valid 'WinCC User Archives' license key.

Where are CEMAT online trend tables stored?

Inside the project database SQL Server instance on the OS Server, within tables prefixed with UA_ or C_TREND.

Can trend groups be imported and exported to CSV?

Yes, the WinCC User Archive editor allows exporting and importing archive tables via text/CSV files for backup.

Technical References

Related Articles

Related Tags

  • CEMAT
  • User Archives
  • Online Trends
  • OS Client
  • Standard Server
  • WinCC V7.5
  • SQL Server
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