DP, please except my apologizes for my insensitivity, l blame having lots of below I/Q brain cells. This forum ( all the the other members) will go to stupid amounts of time and effort on their part ( god bless them, even thou l haven'y meet god or his mates yet) to assist people to gain knowledge on PLC's. WHY? it must be all the MONEY you pay them when you write in for free. I haven't worked it out yet (l have but it doesn't help to advertise it, as they are a more knowledgeable bunch than I).
Something to keep in mind, as per nearly every type of forum, use the search engine, as most questions, so most answers have already been said.
MAY the force be with you and your brain start to melt when the PLC code starts going across the screen.