My father-in-law is a retired Service Engineer / Electrician and is a genius with mains powered items like mechanical timers, relays, solenoids and also plumbing systems. He's built himself an automatic watering system for garden, greenhouse and hanging basket using various salvaged parts and wants to consolidate it down to one simple to maintain system.
For this he had a Moeller Easy 412-AC-R programmable relay that he wanted to use to control 4 independent watering systems. His skills (mains, wiring, plumbing etc) are complementary to mine (occasional exercise, drinking coffee, hacking poor quality code) so he asked me to help him program the relay.
The unit is shown on the image below:
- Eight screw terminals to which you can connect mains inputs (240V AC in the UK). These are the "I" inputs at the top of the image.
- Four pairs of screw terminals which are relay contacts through which you can switch mains power items. These are the "Q" outputs at the bottom of the image.
- The cursor buttons that act as "P" inputs.
- A set of other internal controls like counters and timers.
- A UI comprising the buttons shown on the picture above which let you create "circuit diagrams" on the LCD screen.
- An imprecise time of day mechanical switch.
- A precise trigger.
- The Moeller relay with four separate timer controlled relays
- A set of solenoid valves that control the water flow.