PLC home automation via my home PC

Hey there fellow PLC'ers,

I use GE 90-70's and 90-30's currently at work and I've used Johnson Controls controllers in the past so I'm familiar with PLC's but I'm wondering if anyone might know of someone making an expansion card for a home PC with I/O that comes with some software that I can program for home automation type projects? I would think that there has to be something decent out there, ANY pointers would be appreciated!!

There is also a book- Controlling the World with your PC, that I was thinking of picking up, is it any good?

Thanks,

Disco in Colorado

Disco,

I spent several years, several years ago, employing exactly the kind of thing you are talking about. Except I used it for Industrial Automation. The programs were written in "C".

I can not remember the brand name of those cards. However, I used those cards to drive opto-isolated OPTO-22 I/O "Racks". Those "racks" consisted of up to 32 I/O Modules.

Each module was a single discrete module. That is, one module for each Input and one module for each Output. The Inputs and Outputs could be mixed on the same rack.

The card had up to four connectors with four cables. Each cable had four connectors at the rack-end. This made for a total of 512 I/O from a single card.

The I/O was "software configurable". That is, YOU defined whether the particular bit (module) was an Input or an Output. Again, the Inputs and Outputs could be mixed however you wished. That information was included in the process program-code so that the program knew if it was a Read-Bit or a Write-Bit.

I know that the card I used was NOT OPTO-22, but OPTO-22 does have such a card and the required software.


That's the easy part. The harder part is to develop a PLC-type program on the PC - that is, executed at a regular rate. You need to be able to program at the Interrupt Level. That is, at the CPU Interrupt Level. This requires some Assembly Language stuff. If you are using "C", don't be afraid... "C" provides a "Command-Bridge" for this type of operation. There are "C-Commands" that address this issue directly. They are Assembly Instructions within "C".

You need to define your process-program as an Interrupt Routine. You then need to have that routine "called" on a timed-basis. You need to ensure that your maximum program time does not exceed the time between Interrupt Calls. Again, these operations are available directly through "C".

If you are using Visual Basic... sorry, can't help you in setting up the Interrupt Routine. Since this is a home-project, you are not likely to have timing-critical issues. In that case, you should be able to simply make the program loop continuously until you provide a Quit Condition. Bear in mind, that the program will execute at different rates... depending on your code.

Disco,
I don't know if this is what your looking for. Sounds like a cool project! BTW the Data Acquisition Module looks like it uses Visual Basic.
http://www.bb-elec.com/product.asp?sku=SDDRB4&PathId=35&altsku=daqboardchart

Tim

Not sure if it's exactly what you're looking for but you can do home automation with stuff from X10:

www.x10.com

Be forewarned, you will receive copious amounts of advertising e-mail from them if you sign up for anything. These things are also sold (not same name but compatable) at radioshack.

If your looking for a quick and dirty way of doing it, you could use the parallel port in the PLC interfaced to some solid state relays!

Here is a link with info on how to access your parallel port in Visual Basic:

http://www.uct.on.ca/

most of the links on that site arnt complete anymore, but there is tons of places on the internet with info on using your parallel part for control.

Good luck

Cool link Steve!!

Try www.cyberresearch.com They have all kinds if I/O cards and PC based interface and control. Thir catalog is a great reference tool too!

I have a copy of "Controlling Your World ....". My edition is only good for Basic, QBasic, et al. All parallel port control. There are several sites that offer parallel control tutorials but you'll need the appropriate *.dll if you're going to program with VB.

Look at: http://www.lvr.com to download: inpout32.zip or do a search for this file. I downloaded my copy for free. It was created for 32-bit Visual-Basic programs running under Windows 95. I downloaded this a couple of years ago so I don't know how it'll do with 98SE or Win2K.

... rab

You can try DCIPLC , this program is for hobby applications only.

<<
DCIPLC is a ladder logic editor and PLC (Programmable Logic
Controller) simulator that incorporates basic functions
used in PLC Programming.
With inputs, outputs, timers, counters, clocks and flags
you can develop ladder programs. Each function is simply
'clicked' onto the ladder rung with tags assigned via a
pop-up window.
DCIPLC also has the added benefit of being capable of
controlling external applications via a serial port (RS232).
Also included a schematic for building the hardware.
>>

http://home.planetinternet.be/~dc11cd

Good luck