Loving your tech buddy. Definately interested in one day doing something much the same myself but like Bush I am in the analogue stage and have no idea how to build one of those awesome bog thingies. hehe. Subscribed and +rep
Any chance of a design sheet on your plc?
There isn't really a design sheet at this point... the entire system is so modular that its programmed specifically for the users decided behavior. I could try to teach people the basics of PLC's, but in the finality of it the end user has to decide how the inputs and outputs are going to behave with each other.
The controller itself was completely ebay built, to buy high end plc equipment usually means second hand, but the good news is that in the automation industry, it doesn't matter if it has been used, it has still been designed and tested to last an incredibly long time (triac outputs and transistor inputs are tested to millions of cycles). That plc cpu RETAILS for 2400 dollar, I bought that cpu, manufactured only 4 years ago, for 200 dollars on ebay.
There are so many different manufacturers of PLC's. A great, inexpensive plc which would suit any application is made by EZPlc, their programming software, and hardware is incredibly prices. Their racks are also customizable via various input/output cards, and they even support analog input and outputs which is very important if you plan on implementing pid loops.