Cheap PlC/smart relay for a thermostat (challenge)

[allscott]

A coworker of mine who is learning PLC's is not happy with the amount of programming options his programmable thermostat is capable of or any one he can find to buy.

We use AB but obvioulsy using even the lowest end AB PLC's are going to be cost prohibitive for a small project, I have looked at various smart relays as will.

The I/O requirements are basically one TC input and one relay output, or a inexpensive way to turn a TC or RTD into analog. Would also need some sort of display.

I've thought of 100 different different possiblitites but nothing that would be less than at least $300.00

So I challenge the gurus at plcs.net to come up with the cheapest possible solution for an infinetly programable thermostat for a furnace.

Once I have a winner I am going to patent it and sell it to the masses

Bonus points if it can dish up a web page with status and control.

 

[Mickey]

http://www.eternity-sales.com/Entertron/smart-pak.htm

I don't know the cost.

 

[robertkjonesjr]

I'm not sure this is flexible enough for you, but has some capability:

http://www.controlbyweb.com/x300/


Not exactly what you want - that's a lot of features for $300 in qty 1...

PT RTDs into a smart relay, ethernet available (but not at your price point)

http://www.bb-elec.com/product_multi_family.asp?MultiFamilyId=39&Trail=158&TrailType=Main

 

[Archie]

I'm looking forward to the release of this and hope it comes in at under $300

http://www.beckhoff.com/BC9191/

 

[Xsailor]

Challange accepted!

The I/O requirements are basically one TC input and one relay output, or a inexpensive way to turn a TC or RTD into analog. Would also need some sort of display.

I've thought of 100 different different possiblitites but nothing that would be less than at least $300.00

So I challenge the gurus at plcs.net to come up with the cheapest possible solution for an infinetly programable thermostat for a furnace.

Once I have a winner I am going to patent it and sell it to the masses

Bonus points if it can dish up a web page with status and control.

Hey Allscott,

I have been using the MM1010 & MM1012 for the past 3 years or so with no failures (about 2 dozen units).

http://www.selec.com/products.php?category=28

This is a PLC with 8/5 I/Os and options of one or two channels of Analogue Inputs (can be configured for TC, RTD, mV, V) and 1 channel of Analogue output.
Usual Relay outputs.
Tidy LED display - you can configure all the digits, bar graphs and the small tiny LED lamps.

I use them extensively for PID temperature control - attached is an image showing the controller on my bar sealer.
The software is free and based on IEC standard: 61131-3.

PM me if you want me to set-up an email introduction for you.

Gotchas!!
a) The plastic case is due for a design revision - looks a little 'cheap' but does the job well.

Disclosure: I do not work for them but the owner and a few service engineers are well known to me and are a swell bunch.

PS/EDIT: Yes, the deal will be in the ballpark of USD 150~175.

 

[pokajy]

I don't know if it's cheap enough for u, but u can take a look at siemens logo.

 

[BryanG]

Any of the smart relays and a cheap TC to voltage converter. My choice would be a Moeller/Eaton easy512-DC-RC ,a Status SEM213TC and a 500R resistor. Should be within your $300. You could save some money by using the DC-R version that doesn't have a clock function. Can't do the Web page at that price.

If I wanted to be 'posh' I would use the Moeller/Eaton MFD which has a TC input module and you can add an ethernet module. But that goes way beyond your $300.

Bryan

 

[SafewayBread]

These guys have some cheap stuff, Ive gotten a couple of their Click plcs hooked up to the Micro HMIs for some smaller projects, and so far they have been working great. (6-12 months)

This,
http://www.automationdirect.com/adc...ers/1-z-32_DIN_Size_(SL4824_Series)/SL4824-RR
$90

add this if need be,
http://www.automationdirect.com/adc...s_(Stackable_Micro_Brick)/PLC_Units/C0-00AR-D
$80

and add this if you want alot more of a display
http://www.automationdirect.com/adc...nels/3_inch_Panels_-a-_Accessories/EA1-S3ML-N
$150

Total with all options
$320
$170 without HMI

 

[GeoffC]

You could try a microcontroller
http://arduino.cc/en/Main/Hardware
just select a board and add an ethernet 'shield'
I'm in the process of developing a pool pump and heating controller with an ethernet interface using this. Hopefully when done I should have a saleable item.

 

[JeffKiper]

The I/O requirements are basically one TC input and one relay output, or a inexpensive way to turn a TC or RTD into analog. Would also need some sort of display.

Sorry to question your I/O count is this a heat only system? What about air conditioning? There are a few new systems that only use 1 contact for heat. They can but you will loose your fan only option for air circulation.

 

[KalleOlsen]

Another alternative.

http://www.unitronics.com/Series.aspx?page=Jazz

K

 

[OkiePC]

Sorry to question your I/O count is this a heat only system? What about air conditioning? There are a few new systems that only use 1 contact for heat. They can but you will loose your fan only option for air circulation.

Yeah, how much ladder logic can he learn with one in and one out?

I like the seLec unit, but I found a brochure and no manual.

If it programs in ladder logic, I wanna price list and full blown manual.

Hey Allscott,

I have been using the MM1010 & MM1012 for the past 3 years or so with no failures (about 2 dozen units).

http://www.selec.com/products.php?category=28

This is a PLC with 8/5 I/Os and options of one or two channels of Analogue Inputs (can be configured for TC, RTD, mV, V) and 1 channel of Analogue output.
Usual Relay outputs.
Tidy LED display - you can configure all the digits, bar graphs and the small tiny LED lamps.

I use them extensively for PID temperature control - attached is an image showing the controller on my bar sealer.
The software is free and based on IEC standard: 61131-3.

PM me if you want me to set-up an email introduction for you.

Gotchas!!
a) The plastic case is due for a design revision - looks a little 'cheap' but does the job well.

Disclosure: I do not work for them but the owner and a few service engineers are well known to me and are a swell bunch.

PS/EDIT: Yes, the deal will be in the ballpark of USD 150~175.

 

[Sandeep R Mittal]

Have you got some solution? If not then pls give me your mail id. I will offer you the best solution with best prices which Xsailor has offered you. I am from Manufacturer side.

 

[GeoffC]

I just came across these single board plc with onboard digital and analog io and built in ethernet supporting ModbusTCP and built in web server. And cheap, almost too good to be true. Planning to use one on my home automation project

http://www.tri-plc.com/fmd1616-10.htm

 

[BobB]

Man!! Have a look at the Mitsubishi Alpha. Inputs can be programmed to be almost anything. Digital, analogue, temperature sensor etcetera.
Programming software is a bit strange - state logic - but not bad when you get used to it.