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Long periods (8 to 12 hrs) of no trend data, despite excmax and compmax settings of 600 or 3600 seconds.

bnicho.SHL

I have a trend which often exhibits gaps of 8 to 12 hrs between archived points. I have tried changing compmax and excmax to 600, but still these gaps keep coming.

I have tried turning step on and off. No impact.

I have tried turning Compressing on and off, no impact.

The point is not going into bad quality, in fact there is a sister point where this does occur and PI is both (a) responding correctly during periods of telemetry error and (b) also experiences these big gaps during periods where the incoming data doesn't change, despite similar exception and compression settings.

I suspect our SCADA system is not sending data for long periods of time. Perhaps it applies its own exception test and doesn't communicate the value if it is not changing. Can PI be forced to write a value anyway, in the absence of incoming data and no poor signal quality is detected?

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    Without knowing the tag configuration (polled or advise), my suggestion would be to add the tag to the debug information and log any information received. You can then check the logs to see if the tag is receiving information.

    Beyond that... I think PI is only going to write values to the archive after a value is received; for the intervening period, it will either write interpolated values, or, if step is turned on, the old value.

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    Without knowing the tag configuration (polled or advise), my suggestion would be to add the tag to the debug information and log any information received. You can then check the logs to see if the tag is receiving information.

    Beyond that... I think PI is only going to write values to the archive after a value is received; for the intervening period, it will either write interpolated values, or, if step is turned on, the old value.

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