To study the PLC programming can be done by using a PLC simulator on the internet.
There are many PLC simulator on the Internet, they are:
1. Trilogi (http://www.tri-plc.com/trilogi.htm)
This trilogi is a PLC simulator software which has a complete and comprehensive. In this software there are basic instructions, such as the contact and coil, timers and counters. There are also advanced instructions such sequencer to a custom function that can be made with Tbasic language.
2. PSIM (http://www.thelearningpit.com/plc/psim/psim.html)
PSIM is a software simulator PLC that is old enough, because it is still based on DOS. This software is used specifically for the Allen Bradley PLC. To study the Allen Bradley PLC would be very suitable when using this software because of the extra software is to display the exercises with a graphical interface for the application of water filling, mixing and light traffic.
3. Andrea Barbossa (http://www.andrebarbosa.eti.br/SimuPLC Eng/DownLoad_Eng.htm)
From the display looks this software quite interesting. And you do not require registration to download this software.
4. PLC Simulator (http://www.plcsimulator.net)
If you want to use this PLC simulator, it should be online. Because the PLC simulator is connected to the internet.
With this simulator PLC will make it easier for beginners who want to learn PLC programming. In addition those software are special designed for PLC programming, there are also examples to practice programming the PLC.