Moeller
Moeller
http://www.moeller.net/en/industry/automation/index.jsp
PLCS.net
The best place to learn plc programming... always free of course.
http://www.plcs.net/
Rockwell
Rockwell
http://www.rockwellautomation.nl/applications/gs/emea/gsnl.nsf/pages/programmeerbare_besturingen
Siemens
Siemens
http://www2.automation.siemens.com/simatic/controller/html_76/controller_03.htm