Distributed Control

Any hardware type questions or problems for all other Phidget devices.
mikecando
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Distributed Control

Postby mikecando » Sun Apr 15, 2012 7:09 am

I think I am missing a very clear point and I am hoping someone might shed some light.

I wish to use Phidgets for home automation projects and more for fun and hobby. I am envisioning an architecture where I have a master IO board connected to my computer. This master IO board will then interact with slave IO boards where different sensors such as temperature, proximity,... are connected. I did not find a lot of info on IO board to IO board communication?

I envision that the master IO and slave IO communication would be over RS485 so that I could cover longer distances than USB and also have minimum wiring. Basically, I wish to cover ranges of at least 200' with minimal wiring and more flexibility. Having a slave IO board (remote IO) provides future enhancements without much rewiring.

It would be greatly appreciated if someone could extrapolate on my architectural ideas and offer possibly better alternatives? Maybe I am thing old school?

Thank you in adavance

mikecando
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Re: Distributed Control

Postby mikecando » Sun Apr 15, 2012 8:15 am

Trying to answer my own question after some research. It does look like USB is extendable with third party additions. I also saw something about over the Ethernet or possible wirelessly?

Anyone have some insight on how feasible these methods would be. I am guessing a 100' cable could be expensive and a wireless option.

Wireless would be the easiest to install and most flexible but how would the programming be handled (is there additional programming overhead)?

How reliable is each option and how is performance effected?

erik
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Re: Distributed Control

Postby erik » Mon Apr 16, 2012 8:43 am

Your master IO board can be the 1072_0 SBC2. It is a small computer running Linux. It can be connected to your home network using either Ethernet cable or a WiFi dongle. Other boards can be connected to the SBC2 from USB.

Your program can be run directly on the SBC2, or you can have your main PC communicate with it.

We currently do not have an RS-485 solution, but that is something for us to look into eventually.

mikecando
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Re: Distributed Control

Postby mikecando » Mon Apr 16, 2012 9:06 am

Thank you for the response. I understand the architecture. The challenge though is the ability to distribute the IO boards in distances greater than 15 or 20 feet. I am looking for a practical cost effective way to reliably extend the distance to 100 to 200 feet (to cover the area of a house or small building without having to add additional SBCs(just additional IO boards)

It looks like like zigbee (possibly xbee) might be a cost effective way to do this. Has anyone used this approach? Is it possible to mix zigbee with usb?

Thank you for your kind response.

borisg
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Re: Distributed Control

Postby borisg » Mon Apr 16, 2012 9:50 pm

Multiple SBC's can be controlled wirelessly from a single PC and that's the approach that I've taken for my home monitoring system. The USB WiFi modules that Phidgets sells work over a longer distance than I expected as I've got an SBC2 in my shop which is over 100' from the main house and have no problems communicating with it. The SBC2 monitors sensors in the shop as well as an adjacent greenhouse 80' away (laid an 8 conductor cable from shop to greenhouse when ran power to the greenhouse).

Zigbee is another solution and its got good range at maximum power although I don't know of any cheap Zigbee solutions that would allow you to interface to Phidgets sensors. Also, you'd have to write Linux drivers to USB Zigbee devices for the SBC2.

For ease of use, I'd suggest the multiple SBC solution as I was amazed at how fast I was able to setup multiple SBC networks. The only complaint I have is the incredibly verbose data packets that the SBC2's send to the controlling PC.


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