DIY Research and Development

[mbianka]

I've got an electronics background but, don't spend a lot of time designing or experimenting much on board as I'd rather be sailing. I also converted to electric propulsion four years ago and had a not too pleasant customer service experience with a brand name battery monitor:
THE BIANKA LOG BLOG: REPAIRING A XANTREX XBM BATTERY MONITOR DISPLAY
Left a sour taste for them. I do see a need for an electronic monitoring display for sailboats like mine the use electric auxilary propulsion and also conventional powered boats that display the following:

1) + and - current draw (up to 100 AMPS in my case) using a Hall effect sensor preferably one that can fit over 2 AWG marine cable. If it can fit over a cable with a battery connector already on it that is a big plus.

2) Voltage (48 volts +)

3) RPM (tach) of prop shaft

4 TEMPERATURE (up to 200 degrees F)


Put those sensors together in a nice large readable display of about 3 by 3 inches that can stand up to sunlight in the cockpit and also be read at night without destroying night vision sell it for under $100 and I'd certainly buy one.

[Adamante]

Originally Posted by goboatingnow

One was a smart fuse panel board replacing all the breakers with electronic ones.

Such as?

[Matt sachs]

"one nema multiplexer with buffering, flow throttling, and filtering (lifted from the unix kernel and modified).....Is this english? JK I don't know what all that stuff is, but I do know CNC machining if you guys come up with something that needs a housing or a cover plate I'll build it for you.

[goboatingnow]

Originally Posted by Adamante

Such as?

such as this range of units E-T-A: E-1048-8D. - Relays & SSRPC

Nice PCB of these, an AVR to control them, and a little panel PC ( I have a lovely 4" one from advantech) to show you whats going on. All the advantages of distributed systems, without ripping all the wires out.

Dave

[goboatingnow]

Originally Posted by Whimsical

Why?
It is just Can Buss with a proprietry set of PGN's. Nothing wrong with reverse decoding them, many already have been. I saw a site that has done a lot of work on it but i can't find it just now, i found it originally from an article on Panbo.

I have a few wants for my own instruments and bought an Arduino to play with but i don't think they have enough HP So am eagerly awaiting the Ras Pi Raspberry Pi | An ARM Linux box for $25. Take a byte!

Mike

well yes saying its Can bus, its a bit like saying a flute is a copper pipe with holes in it. The problem is that the NMEA protocol is J1939, modified to include some extra features. To my knowledge no truly open source J1939 stack exists, Microchip have one for the PIC , but its not open to use on other micros. It could be used for " inspiration". CanOpen has a stack but Can Open is very different to J1939/NMEA 2K.

The Issues not the PGNs as you rightly point out Kees ( see Panbo) has decoded a lot of them. ( and NMEA recently released the dictionary anyway) Its the lack of a stack. right now if you want to build a NMEA 2K device, you can only license a commercial stack or use a USB gateway ( like actisense). This is all of course before you then pay NMEA the 2-3K license fee to "approve" the product and give you a manufactuer number. Im sure we could get around that though.

Dave

PS also waiting for the Raspi board, its the Version B I want.

[gello]

that was kind of what i wanted to do for a gateway.
use the PIC with its CANBUS stack and peripherals to extract
NEMA2000 PGNs. Then wrap them in a UDP or TCP header
and burp them out on wifi.
Publish the wrappers and the PGN's supported open source style
and create a parallel universe living on wifi with inexpensive
equipment readily
available and replaceable from walmart (a router, touch device,
netbook, whatever).

What am i missing?
I think i have everything on the bench to talk to CANBUS and extract
the NEMA2000 PGNs with a PIC.
I have already done the NEMA183 MUX portion.
Then I would use the PIC ethernet stack to burp these
out to the router via RJ45 and subsequently wifi.

of course it would work bidirectionally so stuff on the open side of the house would go to NEMA 2000.

Sounds like about a $20 device with a bunch of programming time
to break the stranglehold of NEMA and turn all those $1000 instrument
heads into itouch/androids and a copy of OPENCPN for charting.

Am i missing something serious? Is there a legal issue with using the PGNs?
Do I owe someone license fees?
As someone suggested I may need to come up with my own PGN's for
the public side of the net.

All thats stopping me right now is ripping enough active NEMA 2000 equipment out
of the boat with which to do testing. I'll do that later this fall when sailing season is over.

comments?

gello

[gello]

a guy in east tennessee with a CNC mill that knows machining?
man you are a god.
electronics and programming, no issue.
but to me physical design is PFM (pure flippin magic).

glad to hear from you.

gello

[goboatingnow]

Originally Posted by gello

that was kind of what i wanted to do for a gateway.
use the PIC with its CANBUS stack and peripherals to extract
NEMA2000 PGNs. Then wrap them in a UDP or TCP header
and burp them out on wifi.
Publish the wrappers and the PGN's supported open source style
and create a parallel universe living on wifi with inexpensive
equipment readily
available and replaceable from walmart (a router, touch device,
netbook, whatever).

What am i missing?
I think i have everything on the bench to talk to CANBUS and extract
the NEMA2000 PGNs with a PIC.
I have already done the NEMA183 MUX portion.
Then I would use the PIC ethernet stack to burp these
out to the router via RJ45 and subsequently wifi.

of course it would work bidirectionally so stuff on the open side of the house would go to NEMA 2000.

Sounds like about a $20 device with a bunch of programming time
to break the stranglehold of NEMA and turn all those $1000 instrument
heads into itouch/androids and a copy of OPENCPN for charting.

Am i missing something serious? Is there a legal issue with using the PGNs?
Do I owe someone license fees?
As someone suggested I may need to come up with my own PGN's for
the public side of the net.

All thats stopping me right now is ripping enough active NEMA 2000 equipment out
of the boat with which to do testing. I'll do that later this fall when sailing season is over.

comments?

gello

Ok, Firstly the J1939 ( remember Can bus is the hardware low level data transmission) protocol stack is available FOC for PICS, however NMEA2K adds quite a few extra features, in particular a particular address claim mechanism, fast packet protocol and a request feature, J1939 is not backwards compatible, so the PIC stack needs to be modified to make it handle the NMEA 2K specifics.

After that , if all you want is to read messages you could proceed, you have to "make up" the device 8 byte NAME field , that's meant to be unique across all devices. Also NMEA 2K protocol uses the Request feature to extract additional information, including equipment class and function, these are assigned by NMEA, but they could be just randomed up

as to the legal issue, yes technically NMEA 2000 protocol is owned by NMEA, so technically you cant use it without licensing it. obviously for non-production, experiments it wouldnt be a big deal.

If you do decide to add NMEA 2K to the PIC stack, let me know, I might try a port to the AVR can unit.

Just as an aside , Digital Yacht produce exactly the iphone server your described, it serves web pages up ready to go,

Dave

[Adamante]

Originally Posted by goboatingnow

such as this range of units E-T-A: E-1048-8D. - Relays & SSRPC

Took a quick look... a few of questions:

1. In case of controller failure, any provisions for a mechanical reset override on any of these? Otherwise, need to cycle power?

2. What's the regulatory status of these devices in the US? I see it has E1 approval, but apparently that may not be recognized by the US. I am thinking potential insurance issues.

3. Any ideas on cost, say for the E-1048-8C?

[gello]

i have a 5 year old copy of NEMA2000 spec. Do you have a pointer to an
updated one so
i can start looking at the changes required to the stack?
From my first looks, a lot of the CANBUS is in the hardware on the PICs anyway so
if the changes are major perhaps i should do a new stack. To get us back in
an open system it might be worth the effort.

As to the legal issue, I'm not sure we care if they are PGN's if we publish what the open side format is. Perhaps just pass PGNs as a transport which should be
perfectly legal and then map them to our own open spec in parallel for consumption.

I'll take a look at that iphone site.

thx

[goboatingnow]

Originally Posted by Adamante

Took a quick look... a few of questions:

1. In case of controller failure, any provisions for a mechanical reset override on any of these? Otherwise, need to cycle power?

2. What's the regulatory status of these devices in the US? I see it has E1 approval, but apparently that may not be recognized by the US. I am thinking potential insurance issues.

3. Any ideas on cost, say for the E-1048-8C?

Well to cope with electronic relay failure a simple daughter board that contained a standard circuit breaker could be made pin compatible and be used to revert to mechanical operation.

For local controller failure the relay/cb device will continue to operate without any further input. Obviously if the controller was relaying switching commands this would cease. Though again the daughter board would solve that.

2, as to specific US approvals I don't know. They are advertised on the US site. The datasheet only mentions CE and E 1 , question for Eta , they are a very big player in CBs

3
Cost around 15 dollars. In one offs

(they could easily be duplicated up using high side FET and current monitoring and a little PIC

Interesting ?

Dave

[gello]

the digital yacht solution i found
is nema183 only and cautions it will only work with
one device at a time. guess they dodged the NEMA2000 issue by running away.

gello

[goboatingnow]

Originally Posted by gello

the digital yacht solution i found
is nema183 only and cautions it will only work with
one device at a time. guess they dodged the NEMA2000 issue by running away.

gello

Yes that's the case I think. This is why a freely available protocol stack for nmea 2k would be useful for people experimenting.

Dave

[Adamante]

Originally Posted by goboatingnow

Interesting ?

I find the concept appealing, but I’m not sure it’s realistic. Fundamentally, you are replacing a relatively bulletproof electromechanical breaker with a more vulnerable electronic device. Aside from the requisite regulatory approvals, common sense suggests that this type of a device would be unlikely to provide the kind of overcurrent protection a regular breaker does. Case in point: a lightning discharge fries the SSRPC short while also shorting out the front power stage on the associated load device. Result: a toasty boat fire.

One solution might be to use a series connection of a regular breaker and a matched solid-state device such as the SSRPC, but with a slightly lower current rating than the breaker. In such an arrangement, the SSRPC would act as the primary overcurrent protection device, as well as a remotely controlled switch and status monitor. The electromechanical breaker would be left permanently in the “on” position and would serve as a fail-safe backstop in case of an SSPRC catastrophic failure (short).

The ideal device would be an integrated hybrid of an electromechanical breaker with the added functionality of the SSRPC. The front end would consist of the usual breaker reset lever/button, and an auto/manual switch. When set to auto, all control functions would be performed by the SSRPC portion of the unit. When set to manual, the SSRPC would be bypassed in favor of the breaker element.

These integrated units could then be deployed either singly, or in clusters where it would make the most physical sense on the boat, without the requirement to home-run all wiring to the typical centralized panel.

[goboatingnow]

I don't share your failure mode analysis. Using lightening as your basis is too anecdotal, lightening traversing a conventional DC loom can start fires anyway.

The units are specifically designed to act as overcurrent limiters. There's no specific requirement to use specific breakers on a boat.

These devices also allow closer current monitoring , faster response , current profiling over time, timer functions ( bilge pump counting etc) remote switching and other functions available to distributed switching systems. Detailed power analysis and many other advantages over conventional units as well ( fault alarming) Bavarias range of motor boats had moved completely to electronic circuit breakers as have most of the distributed switching offerings. ( and other boat builders)

My idea was to retain the central wiring point as thus is how most boats are wired and in fact makes better sense then distributed power for boats under 50 feet. This system would allow a potential upgrader the advantage of removing the physical panel and recovering that space. The switch functions would be carried out via a 4" panel pc. Distributed panels would of course be possible , no more then daughter circuit breaker panels are used today. But full distributed system require way to much rewiring and there Are significant issues in running DC power busses around boats.


A simple loom protecting blade fuse could be cheaply used to provide doomsday protection.

It's only an idea.