TechTalk – RSLogix5 : JSR Program File Number
JSR (Jump to Subroutine) instructions direct the processor to go to a separate subroutine file within the ladder program, scan that subroutine file once, and return to the point of departure.

But what does U:5, U:6, U:7,U:8, etc. mean in a JSR instruction?
Xybernetics JSR Program File Number

File number U denotes Program File and the number succeeding “U:” is the File Number.

You can determine the File Number for each ladder by right-clicking any ladder and selecting the “Properties…” from the context menu.

Xybernetics JSR Program File Number

Which will pop up a window which will tell you what the File Number is for a particular Ladder.

Xybernetics JSR Program File Number

n1849778
About the
I am a software developer in Calgary, Alberta, Canada with passion in getting my fingers in any new technology. I started software development when I was 10 years old and have never looked back. Now with well over 35 years of software development, I wanted to share some of these key knowledge with the people of the world in the wide web.