PLCs for beginners?

I have going on 20 years in the software business (ugh, getting old) but none of it is embedded or industrial work. How realistic is it to buy a cheap / used PLC and get it working on my brewing system? Can mere mortals figure these things out?

I started last fall with an Allen Bradley Micro 830 system I purchased off of EBAY. The free Workbench has a modern Windows Visual Studio type interface and includes Structured Text, Ladder, and Function Block Diagram logic editors. Depending on your background, structured text has been compared to Pascal and may be a good fit. It has a PID library function with auto tuning capabilities.

My 830 has three expansion slots and it came with a 2080-IF2 . I purchased two 2080sc-IF4U 4 Channel Universal Analog Input Modules that interface directly to Thermocouple or RTD inputs. Onboard it has 14 discrete inputs and 10 outputs.

I don't know if it's a good fit for you but it has a good brewing automation fit for small to medium systems .

It can be done. First determine how much expandability you need. Don't want to limit yourself and find out later your stuck. Automation Direct has some great PLC that will not break the bank. EBay is a good source of used gear. Get the software first for the PLC you want to use, build your logic while you learn. Not too bad. But the DoMore programming is much easier than the older processors.
You can download the DoMore software for free and it's always free. It has a nice simulator too, so you can play with it as if it was really connected to a Processor.

http://support.automationdirect.com/products/domore.html

Well not really but I did as a research project for my thesis. The software side was not hard especially once you get past the massively complex integration issues. Of writing firmware packages. if you have any experience in software. C especially you shouldn't have any issues with an off the shelf platform.