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Digital Trends and Trend Storage on Data Change

Chris

Hello,

We trend a lot of Digital tags, set to 2-byte storage method, but it would be so much better to storage them at a single bit. Also, we use the Wonderware Historian with the connector utility, all of our tags are configured as Analog with the 8-byte Trends stored as doubles and the 2-byte Trends stored as Integers. We have to set the engineering units to T/F and the range 0,1 to help sort them.

We run very fast trending, 100-250ms and it uses a lot of storage, we typically save about 13 months of data per site and I thought it might be possible to use the trigger in the Trend tag configuration to only store when the Variable tag data has changed. Has anybody done this? If so, what was your methods, workarounds and pitfall?

Thanks,

Chris

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  • Hi Chris,
    Apologies for the delayed reply.
    There are quite a few known issues with the V2.1 version of the Connector. I'd highly recommend you upgrade to V3.0 when you can. The upgrade is straight forward. You should uninstall existing version, install new, check configuration settings. Then run the new connector.
    With regards to Deadband, it will have some effect. It won't reduce the amount of samples stored within the Trend archive, since it is periodic. But it may have an impact on any connected Historian system. However most modern Historians have quite good compression algorithms which make this unnecessary. Most customers want high fidelity, lossless sampling anyway.
    I'd say give the Deadband setting a go, experiment with it and see if it makes much of a difference.
    Kind regards
    Olivier
Reply
  • Hi Chris,
    Apologies for the delayed reply.
    There are quite a few known issues with the V2.1 version of the Connector. I'd highly recommend you upgrade to V3.0 when you can. The upgrade is straight forward. You should uninstall existing version, install new, check configuration settings. Then run the new connector.
    With regards to Deadband, it will have some effect. It won't reduce the amount of samples stored within the Trend archive, since it is periodic. But it may have an impact on any connected Historian system. However most modern Historians have quite good compression algorithms which make this unnecessary. Most customers want high fidelity, lossless sampling anyway.
    I'd say give the Deadband setting a go, experiment with it and see if it makes much of a difference.
    Kind regards
    Olivier
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