rayrmelc said:
I would go for certification to show proof that you have the knowledge.
CEI has a good micro course.
I think the chance of anyone in the know caring about a certificate is slim. PLC programming and debug is a lot like doing electrical work. You can do things with a little knowledge and skill, but in many respects if you do not have the experience to know what you don't know you can easily get into big trouble.
It is a lot like DIYer's doing their own electrical work. There are a lot of things they can do quite safely, but there are a lot of things they probably can't and the difference is not always real obvious to the novice.
IMO, the only worthwhile PLC training, beyond the "get familiar with the terms and navigating the software type classes", is actual experience.
I have spent a lot of time fixing the fixes guys have put in out on the floor. What usually happens is half a dozen different electricans or techs, or whomever does such things at the plant, make their own little changes. Often the changes are poorly documented, and usually seems to be whatever it takes to get the plant back into production rather than fixing the real problem. One common thing is an output goes bad so they will move a wire and change the OTE instruction to the new address. But it is entirely possible that the old address is still used as a status bit somewhere and rarely does anyone check for that. After this happens 10 or 20 times, all sorts of flakey things start happening.