How do I make a sensor switch that detects variables?

How do I script a switch that recognizes a variable? To understand the whole thing I explain you what I want to achieve with this script.

Explanation: If a line has the variable 2313 and drives over the switch, a sensor should recognize the variable and depending upon that this train must drive straight out or to the left/right. but there should be another train over these switches, so with another variable for example 1231. (no automatic train)

It would be really helpful if you want to help me, I have a script but it only works with clickdetector. That's not what I want to achieve with it.

Thanks for reading

there's a no spoon feeding rule, also learn how to use region3/touched