This section describes the Programmable Logic Controller (PLC) that I have set up at home. If you are not familiar with PLCs, take a look at the Programmable Logic Controller page on Wikipedia, it provides a useful introduction.

For home use, an industrial PLC is pretty much overkill, most of the functions that it can perform can be achieved more easily using consumer electronics products at lower cost, with a small footprint and less complexity. So, why setup a PLC at home ? The short answer is because I could - used PLCs are pretty common on eBay where they can be picked up at reasonable cost and I wanted one !

As might be expected, PLCs come in many shapes and sizes, from fixed controllers with limited input and output capabilities to large, complex units used in many industries including Oil & Gas, car manufacturing, etc. etc. The most common include products from the likes of Siemens, Omron, Mitsubishi and Rockwell Automation - manufacturer of the well known Allen-Bradley range of PLCs.

Allen-Bradley PLCs include the MicroLogix range, through Small Logic Controllers (SLC 500) to the PLC-5. The SLC 500 is available with a number of different processor, rack size, power supply and I/O options and is the ideal choice for hobbyist use, being widely available second hand.