C135 PCS 7 (PCS7)
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Resolving Information Server Web Configuration and Process Historian Linkage Failures

Resolving Information Server Web Configuration and Process Historian Linkage Failures

When SIMATIC Information Server encounters web connectivity or data extraction failures when linking to Process Historian (PH) or WinCC, the root causes are typically: misconfigured IIS application pool identity credentials, expired digital certificates, or blocked firewall communication over the Terminal Bus. To resolve this, reconfigure the Information Server application pool in IIS to run under a dedicated domain or local service account with database read privileges, verify that the Process Historian Ready component is synchronized, and ensure TCP ports 80, 443, and 1433 are accessible.

Table of Contents

Executive Summary

Following successful setup, SIMATIC Information Server administrators frequently experience operational failures when attempting to configure data sources or render scheduled web reports. Symptoms include 'Database connection failed', HTTP 500 internal server errors, or report templates failing to fetch Process Historian tags. This article examines the communication pipeline between the Information Server web application, the IIS application pool, and the underlying SQL database instances, detailing the resolution workflow for data source linkage.

Architecture and Fundamental Mechanics

Information Server Web Connectivity and Database Communication Mechanics:

  • Communication Pipeline:
  • Client Web Browser -> IIS Web Application (InformationServer) -> IIS Worker Process (w3wp.exe) -> SQL Server Reporting Services -> Process Historian SQL Instance.
  • Application Pool Identity:
  • In IIS, the InformationServerAppPool executes queries against SQL Server.
  • If configured with default ApplicationPoolIdentity, SQL Server may reject the connection due to missing Windows authentication rights.
  • Configuring a dedicated service account (e.g., Domain\IS_Service) with database read rights in SQL Server is best practice.
  • Communication Ports:
  • TCP 80 / 443: HTTP / HTTPS traffic between clients and Information Server web portal.
  • TCP 1433: Microsoft SQL Server relational database queries connecting to Process Historian.
  • TCP 135 / DCOM: Remote management and Process Historian Ready status handshaking.

Step-by-Step Implementation Procedure

Procedure to Re-Establish Information Server and Process Historian Linkage:

  1. Configure IIS Application Pool Identity:
    - Open Internet Information Services (IIS) Manager.
    - Under Connections, click Application Pools.
    - Locate InformationServerAppPool -> right-click -> Advanced Settings....
    - Under 'Process Model', click Identity -> select Custom account.
    - Enter the credentials of a dedicated administrative Windows account (member of Administrators and SIMATIC HMI).
    - Recycle the application pool.
  2. Configure SQL Database Access Rights:
    - Open SQL Server Management Studio (SSMS) on the Process Historian / Information Server machine.
    - Under Security -> Logins, ensure the service account is added.
    - Under User Mapping, map the user to the HISTORIAN database with role db_datareader.
  3. Verify Process Historian Communication in Simatic Shell:
    - On the Information Server machine, open Simatic Shell; verify that the Process Historian node shows active, green status on the Terminal Bus.
  4. Test Data Source in Information Server Web Portal:
    - Navigate to http://localhost/InformationServer -> log in as Administrator.
    - Click Administration -> Project / Data Sources.
    - Select the Process Historian project; click Test Connection; verify status reports 'Connected'.
  5. Re-Run Report Execution:
    - Navigate to Reports; generate a sample process value trend report to verify data rendering.

Verification

To verify data linkage:
1. In the Information Server web portal, navigate to 'Diagnostic Dashboard'; confirm that the connection status to Process Historian indicates 'Online / OK'.
2. Execute a scheduled shift report; confirm that historical values populate without database timeout errors.
3. Check the Windows Event Viewer -> Application log for any lingering Report Server or ASP.NET error entries.

Limitations and Operational Precautions

Operational precautions:
- If the service account password changes, the IIS Application Pool identity must be updated immediately, otherwise all web reporting will stall.
- Avoid running ad-hoc massive data queries across millions of uncompressed points during active production hours to prevent SQL lockups.
- Ensure that digital certificates used for HTTPS bindings are signed by a trusted internal CA to prevent browser security warnings.

Engineer FAQ

Why does Information Server report 'Database connection failed'?

The IIS Application Pool identity lacks Windows authentication rights in Microsoft SQL Server, or TCP port 1433 is blocked by a firewall.

What account should run the Information Server application pool?

A dedicated Windows service account that is a member of the local Administrators and SIMATIC HMI groups with database read access.

What tool manages Information Server data source links?

The Information Server web portal under the 'Administration -> Data Sources' menu.

Can Information Server query both Process Historian and WinCC OS Servers?

Yes. Information Server can connect simultaneously to Process Historian archives and live WinCC OS Servers.

What TCP port does SQL Server use for Process Historian queries?

Standard Microsoft SQL Server uses TCP port 1433.

Technical References

Related Articles

Related Tags

  • Information Server
  • Process Historian Link
  • IIS Application Pool
  • SQL Connection
  • Web Reporting
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