Search Historian with WHERE clause

Ignition
1

I would like to be able to search for values in the historian that meet certain criteria, for example: all values for a given tag where the value is between a high and low limit. Is this possible with any of the built in tools?

Currently, I have a script that queries the historian and I loop through the result to extract the data I need. Just looking for a better way to do it.

Thanks,
Tim

2

Not in the historian functions, no. If you need such stuff in a binding, you might like my view() expression function from Simulation Aids. (-:

3

@pturmel
For your view() expression function. Does it support Ignition 8.
What’s the license of it?
Can we use it free in commercial productions?

4

Well… it did support v8, but broke somewhere around 8.0.2. It is a commercial license, not open source. But I offer it free to use, including in commercial solutions, with free but low-priority support (here on the forum and via email). Fixing it for v8.0.3+ is on my to do list, real soon now… /:

I deploy this on all of my paying customers’ servers, and fully support their use of it. Their upgrades to v8 will therefore make it a priority.

5

Hi @TimE,

Why don’t you just use a query with a where clause? I think it would go something like:

SELECT myColumns 
FROM myTables 
WHERE tagid = myTags 
AND floatvalue > myLowerValue
AND floatvalue < myUpperValue

If you want to make it dynamic you could script the query as you want.

6

@pturmel
Thanks for your suggestion
We downloaded the file and install it. It seems not work on ignition 8.0.4 Nightly.

As workaround, we will use a for loop in python script to find the expected cell in the dataset, even it maybe a little lower efficient than the select function of view() expression.

7

Updated Simulation Aids module tested against v8.0.3 is available here:

https://www.automation-pros.com/ignition/Simulation%20Aids-1.7.8.1909121622-v8.modl

Please report any problems you have with it.