I'm not at all surprised that you are having problems. This is perhaps the stupidest design I have ever seen. How do you expect the CAN transceiver to drive all of that capacitance, transceivers, and the distributed capacitance of the cable besides? There is no accounting for transmitter drive levels or receiver thresholds. You are way better off running a separate data pair and power pair and using the network to power just the transceivers. Use freaking DeviceNet cable -- it was designed for this purpose, and can support in excess of 32 nodes at 500 kbits/sec. It betrays an incredible ignorance of how the CAN physical layer is supposed to operate. Oh and lose the slope control it is just about the most useless of features.

Puttining optional termination resistors on a device is a foolish thing to do. It will definitely bite you when you go to install these devices and you can't quickly decide which devices have them and which ones don't when things don't work. Terminations BELONG on the cable system, and nowhere else.

Just as an exercise, tell me what the input impedance of 32 transceivers, all connected in parallel is?

Have you thought about attending finishing school?
They teach you how to control outbursts of insults like the ones you gave.

 

Have you thought about attending finishing school?
They teach you how to control outbursts of insults like the ones you gave.

Was that your first post on this forum?

 

Well, I'm also trying this approach...and yes, acknowledging the difficulties this might face it is soooo useful if it would work. Power over CANBUS to replace a LED illuminated domotics system; a POE CAN/IP router/HUB/injector; a primary non-POE-standard 24V powered-CAN-loop in the electricity closet to support the AC Relays, input collectors, etc.. (I'm actually still in the phase of HAPCAN). And then remote decentralized units being connected with CAN or IP choice but with power for LEDs, USB charging, 12V . There's nothing on the market in my view; all common node data/DC filtering is for POE and IP signalling.
My question is: Where is the famous end-result ? Where are we now ? I couldn't see the attachment for the first design (the one that was soooo bad).

 

@cdetier Please consider that if there are not products available for this scheme, it may be that it is not a workable scheme. That does happen, not every idea that seems reasonable is able to actually function as intended.
I suggest taking a look at the new fad of two-wire Ethernet, which I have not seenan adequate explanation of the means of it improving performance. Certainly a good quality 2 wire cable may be cheaper than a good quality 8 wire cable, but it really seems unlikely that there are no compromises being made. What we never see mentioned is what the trade-offs were.
So it may be that a totally different communication protocol and implementation will be required.

 

I always wondered why we installed 8-core cable for Ethernet and then only used four cores. How many thousands of tonnes of copper are lying around in network cabling and never being used?

 

The under-utilization of the cable also puzzled me, as well.
My guess is that the technology advanced quite a bit after the standard was "cast in stone", or something similar.

 

@cdetier Please consider that if there are not products available for this scheme, it may be that it is not a workable scheme. That does happen, not every idea that seems reasonable is able to actually function as intended.
I suggest taking a look at the new fad of two-wire Ethernet, which I have not seenan adequate explanation of the means of it improving performance. Certainly a good quality 2 wire cable may be cheaper than a good quality 8 wire cable, but it really seems unlikely that there are no compromises being made. What we never see mentioned is what the trade-offs were.
So it may be that a totally different communication protocol and implementation will be required.

True,
reading this post is actually the first time I started doubting the success of the original plan. Like many others coming up with a design idea is...we want but also need to stick to it...(at least for a while).... because 1) what if...Eureka! 2) there are country specific market driven reasons to do it. Here in Portugal (and I'm Belgian); we are obliged to install centralized UTP (CAT 6 now) all over the house (liberation of the telecom market); and off course it's hardly used because people use a hotspot and then wireless and then even IP over AC feed as marketed by the operators. Going IP or ethernet seems a smart thing to do ; but I have a few no go's here; IP stacks are more expensive, big brother will soon take control of your fridge, already the CISCO's and big players jumped on it (and without success; check POE lighting systems). I'm also ecologically aware; passive house certified and concluded we need to reduce tubing and cabling and enable renewable energies and enable more interfacing and modular design:
For now:
DC grid, DC microgrid, DC POE++ on the core; DC POE+ for the housing (I know it's not enough power just yet - what I'm aiming for is a hierachical distribution way). And then I thought CAN, (and LIN and I2C and POL convertors). Btw; with 802.3at (2-pair) at 30W it will work as it's not really power over CAN.

 

@Ian0 , @MisterBill2 ; you are asking about UTP or CAN in this case ? UPOE bt uses all 4pairs, 1Gbps also; HAPCAN also (24V over cables to reduce voltage drop; but then not efficiently done in my opinion). CAN itself; I don't know; industrial, RS232 historical reasons.
I'm happy you guys are answering .
Where can I find the bad design then ?

 

Where can I find the bad design then ?

The application notes are linked in Post #7

 

True,
reading this post is actually the first time I started doubting the success of the original plan. Like many others coming up with a design idea is...we want but also need to stick to it...(at least for a while).... because 1) what if...Eureka! 2) there are country specific market driven reasons to do it. Here in Portugal (and I'm Belgian); we are obliged to install centralized UTP (CAT 6 now) all over the house (liberation of the telecom market); and off course it's hardly used because people use a hotspot and then wireless and then even IP over AC feed as marketed by the operators. Going IP or ethernet seems a smart thing to do ; but I have a few no go's here; IP stacks are more expensive, big brother will soon take control of your fridge, already the CISCO's and big players jumped on it (and without success; check POE lighting systems). I'm also ecologically aware; passive house certified and concluded we need to reduce tubing and cabling and enable renewable energies and enable more interfacing and modular design:
For now:
DC grid, DC microgrid, DC POE++ on the core; DC POE+ for the housing (I know it's not enough power just yet - what I'm aiming for is a hierachical distribution way). And then I thought CAN, (and LIN and I2C and POL convertors). Btw; with 802.3at (2-pair) at 30W it will work as it's not really power over CAN.

The present flaw that I experience with wireless ethernet in my house is interference, both from the microwave oven and more constantly from other systems in the neighborhood. everal of them show up with much stronger signals than I get from my cable company provided box. And so when several neighbors are streaming HD movies I need to use a wired connection to be able to send and receive text emails and participate in these forum discussions. Those are certainly not high bandwidth ,high data rate uses. So I consider wireless a second choice, since also it is not very private.

 

Is the safety systems in my car relied on data transmitted over the +12V power cables, I think I’d be taking the train.

That reminded me of "If Microsoft made cars"
https://www.hcs.harvard.edu/pnw/microsoftjoke.htm

https://www.eetimes.com/remember-if-microsoft-made-cars-jokes/#

 

That reminded me of "If Microsoft made cars"
https://www.hcs.harvard.edu/pnw/microsoftjoke.htm

I think #7 is the best
7. The airbag system would ask "Are you sure?" before deploying.
but on my Jaguar XF you did have to press "engine start" to stop it.

 

I always wondered why we installed 8-core cable for Ethernet and then only used four cores. How many thousands of tonnes of copper are lying around in network cabling and never being used?

At work campus they installed 2 pair CAT5, 10bT and had to rip it all out. They went to IP phones after I left. That probably meant POE ethernet switches.

I have some of that crappy cable at home. I have 250' of two colors CAT6, but really haven't installed it yet. I do have a patch panel installed, a 48 port CAT6. I probably should have used a blank Keystone panel.

I have a telco panel ready to be installed too, at least for part of the house. It would be a bridged 12 port, I think.
Any telco locations that get upgraded would be CAT6 with RJ45 ports with inserts to turn them to RJ14's.
I haven't decided what telco patch might be. It could be a specific color of CAT6 or silver satin 2, 3 or 4 pair with telco modular and inserts.

 

11. No, we stop here; Windows 10 is the officially supported version. v11 is for Beta users only.

Here goes another beta solution for the whole threat - after a fruitful research and rapid conclusion I might say but off course that's why we have a forum...to ask your thoughts...

CANH and CANL will probably never work on POE 4 pairs or any long power wire. (too much DC, no common mode filtering possible)
Yes, there are some discussions:
1) SPI (the TxCAN ,RxCAN equivalent) over longer distances (https://www.analog.com/media/en/technical-documentation/data-sheets/LTC6820.pdf) but I don't thrust this. (noise levels, extra isolation, ...)
2)convert to RS485 (or other) so it uses all 8 wires using a master-slave configuration but then all kinds of problems.

I noticed however, the PIC18F66K80 having 2 EUSART interfaces and is a physical + datalink protocol that matches our power needs - I would say differential and 2 wires + GND [ confirmation needed ]
https://www.silabs.com/documents/public/application-notes/an1273-uart-interface-si34071-pd.pdf
and
http://www1.gcanbox.com/fsd/canzxwg/272.html

The idea would be to have:
[topology]:
sensor or LED luminary (let's call this "far spoke") <----> CAN spoke <----> "Mirrored" CAN hub for decentralized spokes and DC power grid <---> centralized CAN modules with also AC
[communication and ports]:
The Sensors or other would use LINJ2602
The LED luminaries would use power (over POE?) + relay outputs or PWM; That's still unresolved but there's plenty of PWM outputs on a CAN modules + those POL convertors
The CAN spoke would interpret the sensors via the EUSART1 of the PIC (eg. PIC18F66K80)
The CAN spoke would use some internal power from the hub POE (injector - PSE) but would mainly redirect this power to the LED luminaries (where it is really needed).
The CAN spoke would further be connected to his "mirrored" CAN hub port counterpart via EUSART2 over POE-4pairs.

The CAN hub port has the same PIC and uses his EUSART1 to connect to his CAN spoke; UART was actually made for intra-IC communication. The CAN hub port would be hardwired in bus way to the other ports serving other spokes as well as connected to the central CAN modules. I like the HAPCAN.com ones. POE over 4 pairs (eg 802.3bt class x and negotiation) would be inserted at the hub. Maybe go from 1000Mbps to 10/100 Mbps to allow for CAN in favour of high-speed IP but still allow it. (+ find some ethernet port mismatch preventions)

Ẽthernet, reading data, controlling remotely all can be done via the central hub using the gcanbox add-ons

@Ian0; I can imagine your home-build. I personally love the network cables more than the electrical wires so the aim here is to use as much as possible the over-dimensioned but legally required space in the telecom closet to distribute power via DC-POE-grid. Also, my background is domotics but I'm tired of explaining the customer they'd need a bigger closet.

If your objection would be ; why you use CAN modules then decentralized. it can be simpler ? then maybe the answer would be to be able to use the same components in the rack as well as distributed.

As I'm neeeew to CAN...can MCU's like PIC be "mirrored" ?
How much programming will be involved ?
Could this actually work for any 2-wire domotics protocol ?
Would I still need CAN transceivers in the hub / in the spoke ?

No pictures yet; mouse not working; but you get the picture

 

At this point it will be useful to stop and discover exactly what functions all of this hardware is required to provide, and do those functions need to have backup redundancy? There is a deadly monster known as "feature creep" that has repeatedly taken well thought out systems that would be fast and efficient and quite economical and inflated them into obese behemoths that did everything, but did none of it very well, and that were very difficult to implement and almost i possible to service. The software asociated with these systems is politely called bloatware, the correct term is rather offensive to even spell.

 

hi Mister,
Are you Project Manager or a really smart designer? Anyways, I hear you. I was a project manager myself for years (for others) but now this is my project.
The problem is the market is no longer ready for designers like us. Either we have to buy 10000 units, or evaluation boards, or the stuff that is around (well at least in Portugal), is outdated. Or automotive-rated 100€ a piece. I would have had a design POE already with 2 pairs but that wouldn't be a solution. How are you guys seeing this?

Scope creep enters because we protect our wallet not wasting energy and money on designs that are nothing new or incomplete. And we need all kinds of skills; electronics, programming, looking hours at specs, patience, being nice to people on forums, ...

 

Wanted to share this:
https://www.onsemi.com/pub/Collateral/AND8351-D.PDF

 

I have managed a few projects and done all of the electrical design portion of a whole lot of projects that were sort of big, as well as those that were rather small. From a hand held calibrator to a big crash sled system, and industrial test machines from engine testers to testers for the control valve for operating that rear opening on a large transport plane. Lots of testing and checking systems. And also installed computer network wiring for a friend who moved his busines to a new buuiding to have many more employees. And pulled in the 480/3 phase when another employer moved to a new location.

And now I am wondering if the system being discussed is all new, or is it a major upgrade of an existing system of some different kind? Sometimes the big cost is putting in the new wires, other times the big cost is the new hardware at the nodes, and the learning curve with the new software. So the question becomes what are you starting with??