OT: Home automation projects

I'd like to see/hear about some of the things you've all done at home with the extra PLCs you could get your hands on.

Here at work I set up a PLC to control an overhead door. We have a 3 button (up/down/stop)control on the inside.It works anytime. We have a key switch on the outside which only works during business hours. It doesn't work on holidays or weekends. The door closes automatically in 15 seconds if the photoeye is clear. The auto close timer can be extended to 15 minutes by pressing a combination of the inside buttons. The key switch has to be turned 5 times to activate, if the door has not previously been opened that day and the time/date are right. The key switch can be activated during off hours by pressing a combination of the inside buttons. The clock sets itself forward and back for daylight savings time.

I have about 10 PLCs in my office that I can use for projects if I want to.

I am currently remodeling my house and using a plc and hmi to control hvac and certain lights. also working on using it for controlling my big shop doors, and possibly a security/fire alarm system

I use a S7-1200 to run my pool heating system!Soon it will also control my veggie garden mini irrigation system. It is overkill but it is what I had lying around. I definatly get some raised eyebrows. Espescially from my old man who has no clue what a PLC is and I probably couldn't explain it to him in a lifetime.

I haven't done this yet, but plan is to automate my wife's chicken coop with temp controlled heat lamp and water de-icer, auger fed automatic feed dispenser, automatic door controlled by sunlight, etc...
I have an SLC500 rack to work with.

That is this springs project.....I will post some pics and specs when it is done.

Dave

Why don't most of you guys just use a microcontroller instead of a PLC? It's so much cheaper and it can do practically the same. Correct me if I'm wrong.

Espiration said:

Why don't most of you guys just use a microcontroller instead of a PLC? It's so much cheaper and it can do practically the same. Correct me if I'm wrong.

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Because I had the opportunity to get a PLC cheap, and I enjoy doing it, and I am teaching my son while having fun building something together.

Dave

Espiration said:

Why don't most of you guys just use a microcontroller instead of a PLC? It's so much cheaper and it can do practically the same. Correct me if I'm wrong.

Click to expand...

I simply had the 1200 lying here that I purchsed as a trainer.
What better way to learn than just do something with it! Even a simple application like garden irrigation and a water heater is still practice.

Espiration said:

Why don't most of you guys just use a microcontroller instead of a PLC? It's so much cheaper and it can do practically the same. Correct me if I'm wrong.

Click to expand...

They're not cheaper than free. I have 10 PLCs sitting in my office and I didn't pay a dime for any of them.

Espiration said:

Why don't most of you guys just use a microcontroller instead of a PLC? It's so much cheaper and it can do practically the same. Correct me if I'm wrong.

Click to expand...

As others said, these are usually with used PLCs that were just lying around, so they were free. Also, we know how to program PLCs and don't have to learn how to program microcontrollers.

A friend gave me a bunch of sprinkler heads last year, and I got 4 3/4" solenoid valves off an old EDM machine we scrapped out, so I made my own sprinkler system controlled with a Click plc ( 70 us dollars) with a timed drum instruction to start the first zone at midnight, second at 1 am, etc., off for 20 hrs, start the cycle again with the completion bit. Couldn't be happier with the bang for the buck with the Click.

I don't work in the controls industry, though I've been interested in electricity/electronics and programming for a long time. A home automation project is actually what led me to begin learning about PLCs.

I started out wanting to build a lighting control system using the venerable GE low-voltage switching relays, which are mechanically-held latching relays with separate On and Off coils, and pilot contacts. I planned on using time-delay relays to generate pulses for the relay coils, to allow ordinary maintained-contact switches to operate the system in place of the SPDT momentary-contact switches normally used with the relays. But the cost of the time-delay relays led me to look for an inexpensive PLC (at the time I just knew vaguely what a PLC was), and I soon came across the Click series. Of course, once I learned its capabilities, my project's scope grew to include time schedules, master control of groups, and other features.

Also, I added a Modbus/TCP capability (using a GridConnect adapter), which will talk to a Windows PC running Apache, PHP and MySQL as a home automation server. For a cheap touch-screen HMI, I'm using HTML and JavaScript on a Kindle Fire's built-in web browser.

I use a MicroLogix 1100 with four Red Lion G303 HMIs as my combined burglar alarm system, sprinkler system, and to control the hot water recirc pump in my house. Way overkill but nice to have all functions on each HMI. The recirc pump logic watches motion sensors in and outside the bathrooms and runs the hot water recirc pump if the water temperature is below a threshold and the pump has not been run within the last hour: this assures there is immediate hot water everywhere in the house but, to save energy, only runs the recirc pump when there is movement near a bathroom.

When I built a newer house I just used a commercial-style Honeywell burglar alarm instead and gave up on the PLC - the new burglar alarms have great online features, ZWave thermostat integration, and gives me the weather report on the color touchscreen. ZWave integration and weather report were always on my list for the PLC-controlled house but I never got to it. So I opted for the off-the-shelf solution on the newer house and tossed the PLC idea. It was a bear to learn the Honeywell alarm programming but essentially no different than the difficulty of learning a new PLC.

If it counts as 'home automation', I also put a MicroLogix 1100 and Red Lion Data Station on our 8 second 1000 HP blown alcohol drag boat. It keeps trends on cylinder temperatures and RPMs for each run and controls the clutch and shifting to help improve consistency between passes. The trends are invaluable to ensure the motor is properly tuned (not running too lean - real expensive to do that....kaboom) and the clutch/shift control helps keep each run on the same number in spite of barometric pressure, temperature, and humidity changes.

How do you guys handle the do-it-yourself home automation when you go to sell your house? I know that most times, the various loan agencies and bank loan officers will require that the home systems be put back to "normal" before they will approve a loan. Do you tear out all the PLC stuff and go back to scratch, or what?

Lancie1 said:

How do you guys handle the do-it-yourself home automation when you go to sell your house? I know that most times, the various loan agencies and bank loan officers will require that the home systems be put back to "normal" before they will approve a loan. Do you tear out all the PLC stuff and go back to scratch, or what?

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Hmmm. Not run into that issue but sounds entirely plausible. I would guess you may get questions depending on how you did the home automation, what brands you used, how professional it all looked. There are some really expensive homes with incredible automation systems out there. Interesting view that anyone would fault a PLC for reliability or ubiquity. Assuming I'd done a professional installation just like any of my customer jobs, I'd want to sell them on the amazing reliability and millions of installations of PLCs - and teach them a little about our wonderful controls world.

I'd want to have a discussion with that loan officer: if i can't sell someone that a PLC is the safest, most reliable, most time-tested, most common approach to reliable control compared to some $100 inexpensive off-the-shelf burglar alarm, then I would be disappointed in my sales skills. Would be kind of a fun challenge to get that loan officer over to the dark side...