# Power Chart Annotation with derived Pen Source **URL:** \ **Category:** Ignition\ **Tags:** perspective\ **Created:** [May 21, 2024, 3:16am UTC](https://forum.inductiveautomation.com/t/power-chart-annotation-with-derived-pen-source/90650 "2024-05-21T03:16:25Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Craig\_Rathbone](https://avatars.discourse-cdn.com/v4/letter/c/3ec8ea/32.png) [@Craig\_Rathbone](https://forum.inductiveautomation.com/u/Craig_Rathbone)\ **Post date:** [May 21, 2024, 3:16am UTC](https://forum.inductiveautomation.com/t/power-chart-annotation-with-derived-pen-source/90650/1 "2024-05-21T03:16:25Z")
Here's a fun one, probably not enough for me to raise a support ticket, but interesting to see if it's just me: I have a PowerChart, and I have set it up to be dynamic depending on a few parameters and custom values (URL is used to distinguish site/system). I have an expression used for the pen source: `{view.custom.tagRoot}+"sys-a/bms/sys-a_hex-a_oil-flow/value"` where tagRoot is just setting the history driver and the root of the path... For example, it calculates to: `histprov::/drv:sin02-hc01:/tag:sin02/hc01/` and then the pen data source therefore becomes: `histprov::/drv:sin02-hc01:/tag:sin02/hc01/sys-a/bms/sys-a_hex-a_oil-flow/value` This is all good and correct, data displays fine. HOWEVER: I cannot place annotations on this pen.... If I remove the expression binding and cut and paste the above, it all works ok. I'm not to sure how to troubleshoot this (or if it can)... I understand why you cant write to an expression binding if this was for example a tag, but I didn't think the tag datasource in a PowerChart would work the same (and you cant map a indirect tag to this and set up bi-directionality as it has to have the history provider etc. in the source)...... Anyone seen this or have any suggestions for how I could set this up to work dynamically..... for our commissioning I've had to set up dozens of trends manually just so we can annotate. And interestingly(?) it will display annotation on the dynamically made tag if there's an annotation set from the non-dynamic trend...... ---
**Author:** ![Anthony\_Phan](https://avatars.discourse-cdn.com/v4/letter/a/e56c9b/32.png) [@Anthony\_Phan](https://forum.inductiveautomation.com/u/Anthony_Phan)\ **Post date:** [December 6, 2024, 4:58pm UTC](https://forum.inductiveautomation.com/t/power-chart-annotation-with-derived-pen-source/90650/2 "2024-12-06T16:58:45Z")
I've run into this too. Have you found a fix for it? Can confirm that I can't add annotation notes to the dynamically added pens, but if I add one using the tag browser button on the power chart I can add an annotation to the newly added pen from there. ---
**Author:** ![Anthony\_Phan](https://avatars.discourse-cdn.com/v4/letter/a/e56c9b/32.png) [@Anthony\_Phan](https://forum.inductiveautomation.com/u/Anthony_Phan)\ **Post date:** [December 6, 2024, 11:27pm UTC](https://forum.inductiveautomation.com/t/power-chart-annotation-with-derived-pen-source/90650/3 "2024-12-06T23:27:42Z")
I figured it out. In the power chart, you have to set the pen as selectable. I'm using perspective by the way. ---
**Author:** ![Craig\_Rathbone](https://avatars.discourse-cdn.com/v4/letter/c/3ec8ea/32.png) [@Craig\_Rathbone](https://forum.inductiveautomation.com/u/Craig_Rathbone)\ **Post date:** [January 30, 2025, 11:08pm UTC](https://forum.inductiveautomation.com/t/power-chart-annotation-with-derived-pen-source/90650/4 "2025-01-30T23:08:49Z")
Thanks tfor finding that out. That didn't fix my issue however it appears my full history 'data' field was slightly incomplete... it was good enough to DISPLAY the trend but wasn't enough to be able to write annotaitons. so I had: histprov:[history source]:/drv:sin02-hc34:/tag:...... and it should have been: histprov:[history source]:/drv:sin02-hc34:sin02-hc34:/tag:..... (My edge gateway and history provider have the same name. I did a compare between the browsed version and my expression and noticed this bit was different.) Good find on your part though, have confirmed that you cant write if not selectable (just wasn't my cause).