# Unexpected UDT Tag Parameter Arithmetic

**URL:** <https://forum.inductiveautomation.com/t/unexpected-udt-tag-parameter-arithmetic/43267>\
**Category:** Ignition\
**Created:** [February 10, 2021, 9:32pm UTC](https://forum.inductiveautomation.com/t/unexpected-udt-tag-parameter-arithmetic/43267 "2021-02-10T21:32:36Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![clifford.ayer](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/clifford.ayer/32/78030_2.png) [@clifford.ayer](https://forum.inductiveautomation.com/u/clifford.ayer)\
**Post date:** [February 10, 2021, 9:32pm UTC](https://forum.inductiveautomation.com/t/unexpected-udt-tag-parameter-arithmetic/43267/1 "2021-02-10T21:32:36Z")

</div>

Hello,

Long-Time Lurker, first time Poster!

v8.0.17

I am running into an issue with UDT–\>Reference Tag–\>Source Tag Path --\>Parameter Math

Here is my Source Tag Path

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/e/1/e199abc33558dd46a9fea22b1178ae124620e901.png)

{Gateway\_Number}, {Node\_Number} and {Node\_Num\_Again} (yes, I know: Node Num Again…) are all Integers on my UDT Parameter Types. I am receiving three, two-byte messages of Bit-Packed Data from my Device so I need an algorithm to take the Node Number (1-47) and figure out which group # it belongs to first before retrieving the value on the data array. Note: Element [0] of first group should be ignored (it’s the gateway device I am using). So I figured I’d do this:

Ex: Node 17  
Parameters: Gateway\_Number = 2 // Node\_Number = 17 // Node\_Num\_Again = 17

My math: { (Node\_Number / 16) + 1} → { (17 / 16) + 1} → { 1 + 1} → {2}.  
Thus, I should get something like this :  
[default]Perspective/Gateway\_2/PhotoEyeGroups/PE\_Group\_2[1]

What I actually get:  
[default]Perspective/Gateway\_2/PhotoEyeGroups/PE\_Group\_2.065[1]

When I read the documentation, it says Division within UDT Parameters is allowed, and all Parameters are Integers… What gives? \*Also, I have tried Parameter Formatting, e.g. { (9/16) + 1 |0} which will yield 2 instead of 1.