NAV 2015 cannot integrate with Weigh Device

Hi,
I'm using NAV 2015 CU 31, and trying to integrate NAV with weigh Device. The Weigh Device is connected to PC using LPT Port converted to USB. We already setup the device, so if we push a button in the device, it can scanned the scale (ex : 2.02 KG) and paste it to notepad.
The 2.02 KG will show in notepad.

Problem when using Dynamics NAV 2015, the value cannot be showed in NAV input text.
This problem doesn't happen when I'm using NAV 2016.

The question is, how to integrate the weigh to NAV 2015?
I'm thinking using dotnet object. Already found the sample code in C#, but still have a little clue how to implement it in NAV page.

Thanks