plc drawing software

hello,

for my diploma I have to draw some
ladder diagrams.
But I cannot find a proper software.
I've already tried the mitsubishi medoc
and siemens simatic.
But both are specified to their companies.
What I prefer, is a software which
doesn't betray immediately which controller is used. (i.e universal ladder
diagram editor) Have somebody a clue about
a program/software (freeware)?
Maybe somebody knows what's the name of the editor, that's used on this "learn plcs" site.

regards
Wolfi

http://www.thelearningpit.com/lp/dwnloads.html

The link above is supose to simulage RS Logix 500. It is not meant for a PLC, it is to learn lader logic and test code out in software. If you are looking to program a specific PLC then you will have to purchase the software from that PLC manufacturer

I am a little confused

When you say "ladder diagrams" do you mean ladder logic ..ie plc?
OR
Do you mean a ladder diagram of the system..ie the input power, E-Stop, Control Relays, plc inputs and outputs etc etc?

Since you said "draw" I think the latter, try this demo, its restricted to 25 rungs I believe but is OK. I also believe they offer student discounts.
http://www.cmhsoftware.com/

Hello !
Why don't use AutoCad..
Normally in projects you draw the diagrams with this kind of software before you program them.