project-ladder diagram format

I am doing my graduation in Computer Science engineering.As my project,I have to build a ladder diagram compiler which conforms to IEC 61131-3.
I have gone through Programming industrial control systems using IEC 61131-3 by R.W.Lewis.But i am not builing an editor for LD.
I have to assume a file format(how it is stored on disk) and start my project.I got held up there.Any help regarding file format for LD and any suggestions would be appreciated.

With regards
Y.Suresh

old ladder diagrams were stored as tokens same way as basic did.
so a code for and, or etc.
so do not make it to difficult and use Standard text as input.
make yourself a small program to show it as ladder.
from the standard text write down to
like if word is and do subroutine from memory and input.
please think of the kind HP uses in calculatores.

Thank you shooter for ur help.I have started working on your logic
with good results.

You didn't mention what platform or language (details, details), so I hope that this helps:

http://membres.lycos.fr/mavati/classicladder/

Use the source(s) Luke.


Don't know about compatibility with IEC 61131-3 tho.



John