VirPLC

VirPLC is a Virtual Programmable Logic Controller emulator - PLC simulator with Ladder - KOP program on one screen and with a handy simulator HARD with multimedia effects in the other screen.

VirPLC is a tool for learning to program PLCs.
VirPLC can also do a real hardware control using a PC as PLC. On the top row you will find an OPTIONAL scheme with 9 inputs and 8 outputs through the LPT parallel port of your PC. Although the board incorporates I/O status LED's, by itself, without support or models of real systems, has no realism comparing to the virtual HARD screen. However, if this option has many followers, I could make the outline of tracks (PCB).
In any case I would value an message , both to tell me if you are using it in any institute, university or academy, as well as for any suggestion for improving the program.