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Question

Unknown values for digital tags

  • June 15, 2026
  • 1 reply
  • 25 views

Hello Community,

We are experiencing a strange issue on one of our trend charts and are hoping someone can point us in the right direction

We are trending a PLC tag for a pump/valve that strictly has two operating states: 1 (Idle)and 2 (Running). The data flows from the PLC to our historian, and we are visualizing it inside TrendMiner.

The Issue:
Instead of seeing a clean block or step chart alternating between 1 and 2, the trend line is occasionally jumping or spiking to values like 5 or 6. None of these values exist in the PLC logic for this device

1 reply

Jef Vanlaer
Community Manager
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  • Community Manager
  • June 16, 2026

Hi ​@TIM 

To investigate this in detail, please create a technical support details by sending an email to support@trendminer.com using your company email address. Please include screenshots, ideally from TrendMiner and the direct data source.

In the past, we’ve seen similar situations where the historian does have alternate values during start-up / shut-down or to indicate a data issue. If these get corrected recursively, TrendMiner might have picked up these values already.  In this case, a refresh of the index would solve this.

Kind regards,
Jef