# Perspective power chart missing line segment

**URL:** <https://forum.inductiveautomation.com/t/perspective-power-chart-missing-line-segment/104351>\
**Category:** Ignition\
**Tags:** perspective\
**Created:** [March 28, 2025, 7:52am UTC](https://forum.inductiveautomation.com/t/perspective-power-chart-missing-line-segment/104351 "2025-03-28T07:52:47Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![BVTV](https://avatars.discourse-cdn.com/v4/letter/b/e5b9ba/32.png) [@BVTV](https://forum.inductiveautomation.com/u/BVTV)\
**Post date:** [March 28, 2025, 7:52am UTC](https://forum.inductiveautomation.com/t/perspective-power-chart-missing-line-segment/104351/1 "2025-03-28T07:52:47Z")

</div>

I am using the power chart, and am experiencing problems with points that are not connected by a line. In the first picture, it seems like the chart forgot to interpolate between two points. Seems like it is mostly happening in periods where the value was constant.

However, when i try to plot a third tag, the problem disappears. Why? What can i do to make this work reliably?  
There was no error on the tag value in the period. I want all the lines to be connected (but bad quality values can still be missing).

By the way, my historian stores a data point once every hour if the value does not change.

 ![Curves_x2](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/d/1d0da070a3a9c632c0a425b43ff87c5e1b5c129d.png)  
 ![Curves_x3](https://us1.discourse-cdn.com/inductiveautomation/original/3X/3/f/3f23e7160fb064c81f698f8ca030b19da01e5ad0.png)  
Ignition version: 8.1.35

---

<div class="post-metadata">

**Author:** ![BVTV](https://avatars.discourse-cdn.com/v4/letter/b/e5b9ba/32.png) [@BVTV](https://forum.inductiveautomation.com/u/BVTV)\
**Post date:** [March 28, 2025, 8:20am UTC](https://forum.inductiveautomation.com/t/perspective-power-chart-missing-line-segment/104351/2 "2025-03-28T08:20:12Z")

</div>

I used this query to get the historian data for the tag:

```python
SELECT DATEADD(s,t_stamp/1000,'1970-01-01 00:00:00') as timestamp, floatvalue,dataintegrity, querymode, datevalue,intvalue,t_stamp,tagpath FROM sqlt_data_1_2025_03
inner join sqlth_te on sqlth_te.id = sqlt_data_1_2025_03.tagid
where sqlth_te.tagpath LIKE '%myTagPath%' AND t_stamp < 1742987521105
order by t_stamp DESC

```

The data look normal to me, so i dont understand why there are gaps:

 ![HistorianTable](https://us1.discourse-cdn.com/inductiveautomation/original/3X/9/e/9e101a169a67046d501e426dada85d67258d8eef.png)

By the way, the dates in the mssql database is one hour less.

The value comes from an expression tag with execution mode set to event driven:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/1/11e7d3fa32dc7efaec87575d8e8dfdd663f79bfd.png)

And this is the tag group:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/3/4/34c7523d4f8ddacb283896d897488514a4496c51.png)

---

<div class="post-metadata">

**Author:** ![BVTV](https://avatars.discourse-cdn.com/v4/letter/b/e5b9ba/32.png) [@BVTV](https://forum.inductiveautomation.com/u/BVTV)\
**Post date:** [August 8, 2025, 8:05am UTC](https://forum.inductiveautomation.com/t/perspective-power-chart-missing-line-segment/104351/3 "2025-08-08T08:05:32Z")

</div>

This is a typical query i use for inspecting raw historical data in the database:

```python
SELECT DATEADD(s,t_stamp/1000,'1970-01-01 00:00:00') as timestamp, floatvalue,dataintegrity, querymode, datevalue,intvalue,t_stamp,tagpath
FROM sqlt_data_1_2025_07
inner join sqlth_te on sqlth_te.id = sqlt_data_1_2025_07.tagid
where sqlth_te.tagpath LIKE '%cell5/temperature1/value%'
AND DATEADD(s, t_stamp/1000, '1970-01-01 00:00:00') > '2025-07-07 00:00:00'
order by t_stamp ASC

```