# Bug report Interpolation Mode reads incorrectly depending on tagpath value

**URL:** <https://forum.inductiveautomation.com/t/bug-report-interpolation-mode-reads-incorrectly-depending-on-tagpath-value/29042>\
**Category:** Ignition Early Access\
**Created:** [October 12, 2019, 3:45am UTC](https://forum.inductiveautomation.com/t/bug-report-interpolation-mode-reads-incorrectly-depending-on-tagpath-value/29042 "2019-10-12T03:45:32Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![mgraham](https://avatars.discourse-cdn.com/v4/letter/m/9fc348/32.png) [@mgraham](https://forum.inductiveautomation.com/u/mgraham)\
**Post date:** [October 12, 2019, 3:45am UTC](https://forum.inductiveautomation.com/t/bug-report-interpolation-mode-reads-incorrectly-depending-on-tagpath-value/29042/1 "2019-10-12T03:45:32Z")

</div>

I have tested with Ignition 7.9.7 AND 8.03 so I will report it for version 8

Behavior:  
imode = system.tag.read(atag+".InterpolationMode").getValue() returns different answers depending on the tagpath (for the same tag).

Expected:  
Full or partial path should give same result, but the partial path is the one that gives the correct result.  
example:  
full tag path:  
histprov:process:/drv:ignition-sctest:default:/tag:testing/simulator/realistic0  
partial path:  
testing/simulator/realistic0  
both return same trend data, but the full path returns InterpolationMode as None  
and the partial path returns InterpolationMode as Discrete when using system.tag.read as noted above.

I am writing this from home so I don’t have the database version, but it is Mariadb, fairly recent version.

OS is Ubuntu 18,04 for the test with Ignition 8

OS is Ubuntu 16.04 for the test with Ignition 7.9.7 and the database here is MSSQL 2014

One additional note is that Ignition 7.9.7 returns 0 or 3  
while Ignition 8.0.3 returns Discrete or None.

To setup for the test, Install Ignition 8.0.3, and a database, and create a database named process.  
set the default history provider to be the process database  
create a history tag, save it. then go back and change it to have (old terminology = InterpolationMode (Value Mode)) of Discrete. I think the terminology in 8.0.3 is something different like Deadband Style, but the InterpolationMode property gives the same result.

Why does it matter: I use the InterpolationMode to process the data differently depending on the value. I normally get the tagpath from the tag browser which returns the full path, which does not work correctly for this purpose.