Can Timestamp of a Tag be written to using a script

Ignition
1

Hi Folks,
Wondering if a Timestamp of a tag can be forced using scripts or any other methods?
I want to read a timestamp from OPC, separate to another Boolean value from OPC.
These 2 correlate, I want to write the Boolean to a memory tag, and want to force its timestamp to be the timestamp I read over OPC.
I know this can be done using a module and would need this developed, just looking for an alternative. When I do a system tag write it creates a Custom Timestamp but I don’t believe this would be applied to an alarm, it will use actual tag timestamp.

2

You can try writing a QualifiedValue directly; something like:

from com.inductiveautomation.ignition.common.model.values import BasicQualifiedValue
paths = ["path/to/tag"]
values = [1]
qvs = [BasicQualifiedValue(v) for v in values]
for qv in qvs:
    qv.timestamp = system.date.getDate(2020, 11, 25)
system.tag.writeBlocking(paths, qvs)
3

“from com.inductiveautomation.ignition.common.model.values import BasicQualifiedValue
paths = [“path/to/tag”]
values = [1]
qvs = [BasicQualifiedValue(v) for v in values]
for qv in qvs:
value.timestamp = system.date.getDate(2020, 11, 25)
system.tag.writeBlocking(paths, qvs)”

Thanks @PGriffith, This worked, Only thing I had to change was value.timestamp to qv.timestamp.
One to note for anyone else needed this is January is month 0.

1 Like
4

Hi Paul, Will it work if the value didn’t changed. But there might be different timestamp.

5

You could use the same method, you’ll just want to read the tag before you write it to leave the value unchanged. That does introduce a potential race (the value could change between your read and subsequent write) but is likely safe enough.

1 Like
6

Thank you Paul… :pray:

7

Paul, out of curiosity, if this tag we just wrote a value (and timestamp) to is being historized, does the tag historian use this timestamp as the t_stamp to store in the Historian database? Or does the historian use it’s own now() value when inserting upon evaluating?

8

In 7.9 and previous, there were separate notions of timestamp sources, but as far as I know, in 8.0+ the timestamp is basically always calculated in the historian, not ‘trusted’ from the value.

9

Darn. This kindof means I’m out of luck. If I import raw tag data from a CSV file using system.tag.storeTagHistory function, I can specify the timestamp…but I lose out on the deadband optimization the Historian provides so I end up storing way more data than I need. If I instead write to the tag’s value and timestamp, I gain the deadband and alarm functionality, but the historian won’t use my timestamp.