When you change a tag's Sample Mode from On Change to Tag Group, I think it's still enforcing the Min Time Between Samples from when the tag was set to On Change, rather than the value for the Tag Group.
I just tested this:
- Create a tag based on the Sine0 from the device simulator. It has a 1 s update rate. Set the tag to On Change, with a Min Time Between Samples of 60 s.
- Edit the tag and change it to Tag Group, set to Default Historical which has a MinTBS of 1 s. When the Sample Mode is changed, the MinTBS field disappears.
- Result, data is still being logged at 60 s intervals.
- Edit the tag and change to On Change, change MinTBS to 20 s, do not save, change to Tag Group, then save.
- Result: data is now logged at 20 s intervals.
Here's the logged data:
"t_stamp","sine0_tagggroup"
"2026-08-21 15:06:36.217","-15.567328453063965" <-- On change, 60 s MinTBS
"2026-08-21 15:07:31.276","-49.74502182006836"
"2026-08-21 15:08:32.359","-19.125463485717773"
"2026-08-21 15:09:02.401","9.67952823638916" <-- Tag group, should be 1s
"2026-08-21 15:10:02.407","49.65243911743164"
"2026-08-21 15:11:02.414","20.87210464477539"
"2026-08-21 15:12:02.422","-36.81194305419922"
"2026-08-21 15:12:22.424","-47.41008758544922" <-- Changed to 20 s MinTBS,
"2026-08-21 15:12:32.426","-49.678077697753906" but back to Tag Group
"2026-08-21 15:12:52.440","-47.679019927978516" before saving
"2026-08-21 15:13:12.443","-37.416080474853516"
"2026-08-21 15:13:32.445","-20.644412994384766"
"2026-08-21 15:13:52.448","-0.31311002373695374"
When I export the tag, the MinTBS is present:
{
"dataType": "Float4",
"historicalDeadband": 1.0,
"historicalDeadbandStyle": "Discrete",
"historyEnabled": true,
"historyMaxAge": 2,
"historyProvider": "ignitionpg",
"historyTimeDeadband": 20,
"name": "Sine0_TagGroup",
"opcItemPath": "ns\u003d1;s\u003d[Sample_Device]_Meta:Sine/Sine0",
"opcServer": "Ignition OPC UA Server",
"sampleMode": "TagGroup",
"tagType": "AtomicTag",
"valueSource": "opc"
}
