[ISS Support Case] MDAS stopped updating
Last updated: October 17th, 2025Description
MDAS stopped updating on April 2: Historian Client displays Null values for certain tags, despite confirmed SuiteLink connectivity through WWClient. Data does not appear to be logged or visible in trends. Troubleshooting Steps Performed Verified WWClient Connectivity Confirmed successful SuiteLink connection to the IO Server (MDAS). Tested tags via WWClient connection succeeded. However, observed that values were not updating as expected, or returned with poor quality. Historian Reindexing Followed the official procedure (InSource Tech Note) to reindex Historian: Shut down and disabled Historian. Deleted contents of the following directories: D:\Historian\Data\SearchIndex\files D:\Historian\Data\Logs\SearchIndex D:\ProgramData\ArchestrA\HistorianSearch\Logs Re-ran Historian Configurator with Reindex selected. Restarted Historian service. Ran Change Network Account and OS Configuration Utility Executed tool to ensure proper DCOM permissions and service account configuration. Validated results and confirmed account consistency across services. Verified Time Sync Configuration Time Sync parameter on IO Server is set to 1, meaning timestamps are sourced from the PLC/device. Identified potential for timestamp mismatch if PLC time is unsynchronized. Recommended temporarily setting Time Sync = 0 to force server time for debugging. Historian Tag Quality Verification Since the Excel Add-In is not in use, may need to query tag values directly via SQL in SSMS: query: SELECT TOP 100 DateTime, Value, QualityDetail FROM Runtime.dbo.History WHERE TagName = 'SampleTag' ORDER BY DateTime DESC; Analysis of QualityDetail column ongoing to determine whether Historian is rejecting values due to poor quality (e.g., 0x00, 0x40). IO Server and Data Flow Checks Confirmed IO Server service is running. Verified that data is configured to collect from the appropriate source. Reviewed tag configuration in Historian Admin (scan rate, deadband, collection status).
- Author: Kevin Modlin
- Published: October 17th, 2025
Details:
| Product: Historian |
| Version: 2020 R2 |
| Solution: [Solution is visible below when you're logged in and have a current subscription] |
| Date Created: | 04/29/2025 |
| Case: | 97693 |
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