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Two wires bus for data and power

Started by pozz April 18, 2016
marți, 19 aprilie 2016, 11:47:00 UTC+3, pozz a scris:
> Il 18/04/2016 18:55, Tim Wescott ha scritto: > > On Mon, 18 Apr 2016 12:12:45 +0200, pozz wrote: > > > >> There are many commercial solutions for home-automation systems that are > >> based on a two wires bus both for bidirectional data and for powering > >> the modules. The number of connected modules could be high, 100 or > >> more. > >> > >> What is the technology of those kind of buses? Are they simple > >> half-duplex RS485? In this case, how the power can be distributed on the > >> same wires of data? Is the protocol master/slave? In this case, the time > >> to poll all the modules could be some seconds and the reaction of user > >> commands is very bad. > >> > >> Or are there other solutions? > > > > The general idea is that you use diplexers everywhere, to separately > > couple DC and comms onto the same set of wires. > > Any ready-to-use chips or reference designs to suggest? > > > > But -- there's a reason that wireless is popular.
ST7540 ST7538 ST7570 ST7580 ST7590 Mouser have them all
On 2016-04-19, pozz <pozzugno@gmail.com> wrote:
> Il 18/04/2016 16:28, Grant Edwards ha scritto: >> On 2016-04-18, pozz <pozzugno@gmail.com> wrote: >> >>> There are many commercial solutions for home-automation systems that are >>> based on a two wires bus both for bidirectional data and for powering >>> the modules. >> >> There are a few. HART, Foundation Fieldbus H1, Profibus MBP, etc. > > They seem all industrial solutions where the cost is higher than > consumer market.
Nobody said anything about the consumer market.
> HART seems a master/slave protocol,
Mostly, but not entirely
> it can't be used for building automation applications, where you > need a fast response to a push button press.
And now we're talking about building automation?
>>> What is the technology of those kind of buses? Are they simple >>> half-duplex RS485? >> >> No. Typically you AC-couple manchester-encoded (or FSK) data onto the >> wire-pair. You also have to add a filter to your power-supply to make >> it high-impedance at the comm frequencies. > > Are there any ready-to-use cheap solutions? I don't think building > automation products are based on complex and big electronic boards.
Perhaps it would have helped if we knew you looking for cheap, consumer-market, building automation technology. Are you? Are you looking for mains powerline communication? -- Grant Edwards grant.b.edwards Yow! ... I want FORTY-TWO at TRYNEL FLOATATION SYSTEMS gmail.com installed within SIX AND A HALF HOURS!!!
Il 19/04/2016 16:09, Grant Edwards ha scritto:
> On 2016-04-19, pozz <pozzugno@gmail.com> wrote: >> Il 18/04/2016 16:28, Grant Edwards ha scritto: >>> On 2016-04-18, pozz <pozzugno@gmail.com> wrote: >>> >>>> There are many commercial solutions for home-automation systems that are >>>> based on a two wires bus both for bidirectional data and for powering >>>> the modules. >>> >>> There are a few. HART, Foundation Fieldbus H1, Profibus MBP, etc. >> >> They seem all industrial solutions where the cost is higher than >> consumer market. > > Nobody said anything about the consumer market.
Home automation is consumer market.
>> HART seems a master/slave protocol, > > Mostly, but not entirely > >> it can't be used for building automation applications, where you >> need a fast response to a push button press. > > And now we're talking about building automation?
Yes, my original post was about "home automation".
>>>> What is the technology of those kind of buses? Are they simple >>>> half-duplex RS485? >>> >>> No. Typically you AC-couple manchester-encoded (or FSK) data onto the >>> wire-pair. You also have to add a filter to your power-supply to make >>> it high-impedance at the comm frequencies. >> >> Are there any ready-to-use cheap solutions? I don't think building >> automation products are based on complex and big electronic boards. > > Perhaps it would have helped if we knew you looking for cheap, > consumer-market, building automation technology. Are you?
I'm curious about commercial (already on the market) technologies that allow to create a bus with only two-wires for power and data. I'm interested mainly in consumer medium/low price products.
> Are you looking for mains powerline communication?
Is powerline used only with AC mains (230/110Vac)? Home automation systems usually have small devices that are DC powered.
Il 18/04/2016 12:12, pozz ha scritto:
> There are many commercial solutions for home-automation systems that are > based on a two wires bus both for bidirectional data and for powering > the modules. The number of connected modules could be high, 100 or more. > > What is the technology of those kind of buses? Are they simple > half-duplex RS485? In this case, how the power can be distributed on the > same wires of data? Is the protocol master/slave? In this case, the time > to poll all the modules could be some seconds and the reaction of user > commands is very bad. > > Or are there other solutions?
One technology already used in home automation systems is KNX on twisted pair, what is called KNX TP1-256. You have a two-wires bus where DC voltage (about 30Vdc) and data (9600bps) are mixed together. On a KNX bus line you must have a specific KNX bus power supply that injects DC voltage for powering modules on the bus. When one node wants to transmit zero, it puts a load on the bus for 35us. The load should sink as much current as possible to have a decrease of 6-9V on the DC voltage on the bus. The power supply integrates a choke that should make the magic. There are some ready-to-use chips that integrates many useful features: bus coupling, DC/DC, bit decoding and so on. For example, ON semiconductors makes: NCN5110, NCN5121 and NCN5130.
Il 19/04/2016 11:05, raimond.dragomir@gmail.com ha scritto:
 > [...]
> ST7540 > ST7538 > ST7570 > ST7580 > ST7590
Those chips are for powerline (mains AC). Could they be used with DC low voltage (12-24V) too?
Il 18/04/2016 12:12, pozz ha scritto:
> There are many commercial solutions for home-automation systems that are > based on a two wires bus both for bidirectional data and for powering > the modules. The number of connected modules could be high, 100 or more. > > What is the technology of those kind of buses? Are they simple > half-duplex RS485? In this case, how the power can be distributed on the > same wires of data? Is the protocol master/slave? In this case, the time > to poll all the modules could be some seconds and the reaction of user > commands is very bad. > > Or are there other solutions?
Another simple solution, IMHO for very specific situations: http://electronicdesign.com/communications/simple-circuit-communicates-over-low-voltage-power-lines
Il 20/04/2016 09:48, pozz ha scritto:
> Il 19/04/2016 11:05, raimond.dragomir@gmail.com ha scritto: > > [...] >> ST7540 >> ST7538 >> ST7570 >> ST7580 >> ST7590 > > Those chips are for powerline (mains AC). Could they be used with DC low > voltage (12-24V) too?
There is an application note from ST that shows how to use their PLC modem in DC powered bus applications. http://www2.st.com/content/ccc/resource/technical/document/design_note/e5/92/04/77/ad/f4/4e/ed/DM00061910.pdf/files/DM00061910.pdf/jcr:content/translations/en.DM00061910.pdf Other manufacturers make PLC modems that should work in DC bus. For example ON Semiconductor (NCN49599), NXP (TDA5051A, up to 1200bps), Cypress (CY8CPLC10), TI (www.ti.com/tool/24vdcplcevm). There is an israelian company that sells a proprietary solutions: http://yamar.com Did someone use one of those solution? Any suggestions for a low-cost consumer applications? What I need is to have a DC powered (10-30Vdc) half-duplex multi-master proprietary bus with a low bit-rate (at least 9600bps). The number of nodes will be 50-100 at maximum.