# Interpolating tag history to get count for a time or period **URL:** \ **Category:** Ignition\ **Created:** [February 16, 2022, 1:22pm UTC](https://forum.inductiveautomation.com/t/interpolating-tag-history-to-get-count-for-a-time-or-period/56203 "2022-02-16T13:22:44Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Transistor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/transistor/32/3380_2.png) [@Transistor](https://forum.inductiveautomation.com/u/Transistor)\ **Post date:** [February 16, 2022, 1:22pm UTC](https://forum.inductiveautomation.com/t/interpolating-tag-history-to-get-count-for-a-time-or-period/56203/1 "2022-02-16T13:22:44Z")
I have a tag’s value being logged (in the default historian) every time the run status changes (stop-to-run and run-to-stop). The production rate is fairly constant so interpolation should give a reasonably accurate cycle count. The cycle count does not reset at end of shift / batch. What is the best way to get an interpolated count of machine cycles for a period of interest? I’ll be using these for a dashboard display so efficiency would probably be the important parameter. Here’s an example of something that doesn’t quite work. ![Interpolated values](https://us1.discourse-cdn.com/inductiveautomation/original/3X/b/c/bcf0978a1c51535c25e1ea494f08fed524c1cd7a.png) _Figure 1. Test tables._ All three tables are looking at the same tag. 1. The DateTime selector is set to 11:00. 2. This table returns data from 30 minutes before 11:00 (10:30) until 12:30. 3. The ‘AsStored’ data shows a count at 10:54 and the next at 11:08. There is no record any closer to 11:00. 4. Same as (2) but with 1 minute periodic period setting. 5. The value for 11:00 looks about right about mid-way between the readings either side of 11:00 at (3). 6. This has the same binding as (4) but with the period set to 10 minutes and the time period is set to 11:00 to 12:00. 7. The first value returned is that of 11:09 in table (2). It’s not at all clear what’s going on behind the scenes. Is it possible to - 1. Retrieve an interpolated count value for 11:00? 2. Retrieve interpolated count values for 11:00 and 12:00? 3. Retrieve the interpolated count difference between11:00 and 12:00? Further testing gives: ![Interpolated values 2](https://us1.discourse-cdn.com/inductiveautomation/original/3X/e/f/ef3bf7ef94adfd032343b65c87b5b5f9e3d5cfd6.png) _Figure 2._ The Figure 2 tag history binding is set to - Query mode: Periodic. - Period: 1 MIN. - Time Range: Historical. - Start Date: = time setting. - End Date: = time setting. Is this my best approach? Many thanks. ---
**Author:** ![Bryan\_Mason](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/bryan_mason/32/30612_2.png) [@Bryan\_Mason](https://forum.inductiveautomation.com/u/Bryan_Mason)\ **Post date:** [February 17, 2022, 9:11pm UTC](https://forum.inductiveautomation.com/t/interpolating-tag-history-to-get-count-for-a-time-or-period/56203/2 "2022-02-17T21:11:19Z")
I think the _Event meter_ in transaction groups was made for this. Check out this [video](https://inductiveuniversity.com/videos/hour-and-event-meters/8.0). Also, I think this will solve a problem I’ve been working on: the hour meter will measure how long a condition is true. ---
**Author:** ![Transistor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/transistor/32/3380_2.png) [@Transistor](https://forum.inductiveautomation.com/u/Transistor)\ **Post date:** [February 17, 2022, 9:34pm UTC](https://forum.inductiveautomation.com/t/interpolating-tag-history-to-get-count-for-a-time-or-period/56203/3 "2022-02-17T21:34:53Z")
Thanks, Bryan, but that’s not quite what I want. I want to be able to return a reasonably accurate shift production count between two specified times. I’ve updated the question with a screengrab from a test application.