I’m having trouble with the history of a tag that I cannot work out.
I setup history on a tag, and when it’s displayed in a sparkline or chart, it displays data from 6 hours ago. If I look at the database, the timestamp on the data is 6 hours in the future.
Database table:
t_stamp conversion:
The Gateway server is set to UTC+10:
Ignition shows the correct time:
The database shows the correct time:
I’ve tried restarting Ignition, restarting the gateway server, turning history off, then back on, deleting the tag entries from the history database tables. All without success.
Any Ideas what’s going on?
Thanks.
With the help of @Kurt.Larson we’ve figured this one out.
It turns out that the tags causing the problem are being read from a remote OPC UA server with an incorrect time (in the future). When the History Sample Mode is set to ‘On Change’, the timestamp is taken from the source, in this case the remote server. If I change the History Sample Mode to Periodic, or Tag Group, then it uses the Ignition Gateway timestamp and the problem is fixed.
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Why is this a "solution" when you can't use your original "On Change" mode? It's a workaround, the Ignition gateway needs to have the option to allow use of Gateway timestamp.
Actually, the fix is correcting the time and making sure it's synced to a good time source on the remote OPC server.
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