PLC as water valve timer

[pete g]

So you buy the relay/s, which comes with a base that the relay plugs into, line in from the PLC, line out to the valve, relay frys, toss relay and plug new one in...

 

[shooter]

buy a 555 and a transistor that is all you need, costing 5 $.

 

[pete g]

A 555 and a transistor?

 

[OkiePC]

A 555 and a transistor?

And a board to mount it on, and a relay for isolation, a voltage source (variable or calibrated divider) to set the timer value, then you need an off delay too. so two 555s per solenoid and two voltage sources to set the time value. Let's not forget the time making up the interconnections between the devices then double all that, or triple it (how many valves?) and a box to put it in.

http://en.wikipedia.org/wiki/555_timer_IC

 

[osmanmom]

digital/analog timer,multi function mode,

https://www.ia.omron.com/products/category/control-components/timers/analog-timers/index.html

 

[Saffa]

buy a 555 and a transistor that is all you need, costing 5 $.

that's fine if this is for non-commercial use, but if this is for a business then please do use off-the-shelf components that any electrician can troubleshoot in the future. I know a 555 timer and a transistor isn't exactly complex, but when you've got several of them on a breadboard and the drawings have been lost, it's going to take someone a while to figure out what's going on!

I replaced a control system for a two pump wastewater pumpstation recently that had been built using discrete components on a 300x300mm strip board. Beautifully done and still functioning apart from the duty change which wasnt following the selector switch . It was more cost effective for me to replace with a PLC than it was to try figure out which chip was acting as the flip flop for the duty!

 

[Lyndon A]

haha, wouldnt know where to begin...

If you're interested in pursuing this route, I have an example of how to do make a cycle timer function with Arduino at this link.

We also carry a power driver board rated to 3A. This board was actually built to control a 12VDC solenoid valve that was used to automate filling a water trough. It worked pretty well so I decided to put it on the market since I could see it being useful to others.

Arduinos aren't suited for a lot of harsh environments but they are very flexible and there are many applications where PLCs are used that they can be quite effective in. They have a reputation as toys for artists and hobbyists, but in the hands of an experienced user they can enable applications that would have been far too expensive previously.

 

[MaintMike]

Another PLC option: https://www.divelbiss.com/Products/ProductDetails.asp?ProdID=5063.

And the "interposing relays" is a very good idea.