Hi
I have a request from client that he want to log some analog signals at 20ms interval. The data come from Modbus TCP driver with scan class to 20ms with history enable with periodic mode set to 20ms for both MaxTime between samples and sample Rate. But with a i7 CPU @ 2.4 GHz it seems ignition left many samples.
So I wonder what is the min time interval ignition history can log into history?
Is there any trick for this kind of application?
The only way you would ever be able to achieve that rate is if you are logging at the source and pushing it up to the historian, such as with dnp3 or kingfisher protocols. However dnp3 event backfilling isn’t supported yet I don’t believe
Edit: unless you’re @pturmel, then anything is possible 
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I’ve done recordings that fast from Ignition, but not in the Tag Historian. Only with wide tables, multi-row scripted inserts, and careful use of java nonblocking queue datatypes. I’d also be suspicious of the capability of any TCP-based driver protocol.
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We’ve done testing previously with logging data every 100ms and found that the historian would not reliably log all samples. We found it was possible to do this however using the system.tag.storeTagHistory API call from a Python script.
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