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Old 02-02-2012, 08:46   #16
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Re: NMEA N2K - what's wrong with it?

To set up up an DSC call you have to select the call channel (manually).
So just clicking on the target on the display won't do it.
Suppose that's why neither in the NMEA0183 DSC sentences nor in NMEA2000 this is included.

Hubert
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Old 02-02-2012, 13:06   #17
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Re: NMEA N2K - what's wrong with it?

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Originally Posted by bcn View Post
To set up up an DSC call you have to select the call channel (manually).
So just clicking on the target on the display won't do it.
Suppose that's why neither in the NMEA0183 DSC sentences nor in NMEA2000 this is included.

Hubert
Correct. What Nick and I are wanting is a 'click on the target' on a MFD display and have it send the MMSI number and preset channel number to the VHF whereby the radio would sit at the 'Press X to transmit DSC message' screen. Punching in MMSI numbers to a radio is craziness.
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Old 02-02-2012, 13:30   #18
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Re: NMEA N2K - what's wrong with it?

With a 'glass half full' hat on (really), I've been trying to find a defensible position for NMEA and N2k.

It has been stated in previous threads on CF that the cost to put Ethernet/IP/webservers in simple sensors is way overkill that would drive the cost too high.

So let's look at an Airmar depth transducer, analog vs. a 'smart' device (0183 & 2000).

Looking at Blue Heron Marine (chosen as they list both models).

The analog model (all manufacturer specific models are the same price) sells for $105.
Datamarine P79 Fishfinder Transducer P79-RCA | Blue Heron Marine Electronics

Both the 0183 and N2k models sell for $235
P79 NMEA 0183 Depth Transducer P79-235-0 | Blue Heron Marine Electronics
NMEA 2000 P79 Transducer P79-235-N2 | Blue Heron Marine Electronics

A difference of $130 for a smart vs. the analog equivalent.

Hmm, $130 for a RS422 drivers or CANbus drivers and some software.

Let's compare that to the Internet world where commoditization has brought realistic prices.

You can buy a Linksys WRT54g (or whatever new model equiv.), chosen strictly due it's popularity, for $50. This box has got (5) 10/100 ethernet interfaces, an 802.11bg radio, an IP stack, and IP router, web server (for config and firmware update capability), NAT, DHCP, DNS relay, etc. My point, it's got way more hardware and software than any boat sensor needs.

So, what's driving the 'high' cost of smart marine sensors??

NMEA's desire to gouge customers?

Why doesn't NMEA take advantage of the commoditization and adopt putting cheaper interfaces on the sensors?
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Old 02-02-2012, 18:44   #19
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Re: NMEA N2K - what's wrong with it?

DotDun, you are spot on. Technology has completely overtaken NMEA 2k and to some extent CAN in general. Ethernet interfaces are now cheaper then CAN to implement, more widely available with loads of software support, so engineers can easily design them in. Then we could use standard tools such as web interfaces to set them up.

Fundamentally NMEA is a creature of its creators, the marine electronics industry. NMEA 2K was essentially funded by seconding design personnel to the committees. What did we get , a half implemented network that allows manufacturers so much leeway that they can effectively close it.

NMEA could have just taken SAE J1939 , instead they had to mess with it. why certification monies. Fuuny theres no independent certification houses isn't it. The whole thing is that NMEA wanted in on the gravy train. This is what we have as a result.

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Old 02-02-2012, 19:30   #20
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Re: NMEA N2K - what's wrong with it?

Just curious - if we could command N2K to move from CAN to Enet, how would you propose standardizing a form of waterproof Cat5 media? Is there a reasonable example out there already? I think this is one of the material differences between CAN and Enet that is actually quite important on a boat.

Don't get me wrong - I'm a big fan of ethernet, but in it's current standard form I don't think it's usable in any kind of exposed locations. Today's solutions to this problem take us right back to proprietary solutions.

And of course any standards body will fight endlessly over any proposed waterproof media system to ensure no existing company has an advantage over any other, i.e. no existing, proven system will ever get adopted.

I actually think N2K is pretty good. Standardized configuration and upgrade would be great, but where does that actually exist? The best I've seen is a small set of standard parameters that can be set universally (PCI does this), but there are always vendor-specific things beyond that. I don't know of anything that does standardized upgrades. Yes, it's 250k (or whatever), but so what. It's fine for what it does.

Radar and fish finders are already all on ethernet, and I think it's better to focus on how to encourage standardization of those protocols on ethernet, standardize transport of N2K PNGs over Ethernet, and encourage its evolution. And leave N2K for all the stuff that runs through the bilge and up the mast, etc. Proprietary cables are tolerable running to the few expose ethernet devices.

I also think the CAN bus structure is preferable for wiring a boat compared to a star wired ethernet. I definitely wouldn't want to have to home-run the wiring for all my current N2K devices. I had enough trouble pulling the backbone cable through the boat.
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Old 02-02-2012, 19:40   #21
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Firstly the are several waterproof Ethernet connectors. amp do a very nice one as is used on the Garmin. Network.

Ethernet is as rugged or more so and perfectly suitable anywhere CAN is used.

The other advantage is you then can setup and calibrate sensors using a web sever in the device and a simple web browser. Instant device setup. This simply can't be done in 2k. The protocol doesn't exist. ( cause unlike TCPIP which is open 2k is closed)

Secondly you obviously don't understand Ethernet and star hub based systems they are much more reliable then bus systems

It is also possible to have combinations of star bus topologies. So at least you can isolate parts of the network from each other.

Can was designed to be a cheap network in an era of expensive Ethernet. That's all changed, Ethernet is a better solution. Can offers few advantageous, most of which are not much use in a boat.
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Old 02-02-2012, 19:41   #22
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Re: NMEA N2K - what's wrong with it?

As I just found out, the problem is that you can take an NMEA2000 sensor (Airmar DST800) , connect it to another NMEA2000 display device (Lowrance HDS-5M), and it's entirely useless because the all important calibration routine isn't included. What am I supposed to do with a knot meter that reads 7kn at 5kn?

I was naively under the impression that connecting two NMEA2000-certified devices together would work. Well, it does, kind of. "Kind of" is no use at all on a boat.
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Old 02-02-2012, 19:49   #23
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Originally Posted by MarkSF
As I just found out, the problem is that you can take an NMEA2000 sensor (Airmar DST800) , connect it to another NMEA2000 display device (Lowrance HDS-5M), and it's entirely useless because the all important calibration routine isn't included. What am I supposed to do with a knot meter that reads 7kn at 5kn?

I was naively under the impression that connecting two NMEA2000-certified devices together would work. Well, it does, kind of. "Kind of" is no use at all on a boat.
Welcome to nMEA 2k the kind of implemented marine network.
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Old 02-02-2012, 20:02   #24
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Re: NMEA N2K - what's wrong with it?

Oh, is this thread just meant to bash N2K. Well, alright but I'm out of here then.

I do not see the practical use of this. You should put effort into getting N2K to work as good as possible, instead of trying to reverse the decisions made which is not just a little naive to pursue. NMEA nor the industry is waiting for you to tell them how to do their jobs.

In the mean time, you seem to have missed the new N2K switches which create star topology?

Also, Furuno uses the same waterproof Ethernet connectors as Garmin. These are actually standard, I even have them for bulkhead-mount.

ciao!
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Old 02-02-2012, 20:33   #25
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Re: NMEA N2K - what's wrong with it?

Quote:
Originally Posted by twistedtree View Post
Just curious - if we could command N2K to move from CAN to Enet, how would you propose standardizing a form of waterproof Cat5 media? Is there a reasonable example out there already? I think this is one of the material differences between CAN and Enet that is actually quite important on a boat.
Furuno seems to have solved that problem. OK, let NMEA define a waterproof twisted pair ethernet connector. It'll give them something to do.

Quote:
Originally Posted by twistedtree View Post
Don't get me wrong - I'm a big fan of ethernet, but in it's current standard form I don't think it's usable in any kind of exposed locations. Today's solutions to this problem take us right back to proprietary solutions.

And of course any standards body will fight endlessly over any proposed waterproof media system to ensure no existing company has an advantage over any other, i.e. no existing, proven system will ever get adopted.
OK, change the thread pitch on Furuno's connector and use it.

Quote:
Originally Posted by twistedtree View Post
I actually think N2K is pretty good. Standardized configuration and upgrade would be great, but where does that actually exist?

The best I've seen is a small set of standard parameters that can be set universally (PCI does this), but there are always vendor-specific things beyond that. I don't know of anything that does standardized upgrades.
Look at the consumer Internet gateway products. All manufacturers, Linksys, DLink, Belkin, etc. use a web server with a 'Firmware Update' button. That's close enough to a standard for me. Same web page could handle the config attributes specific to that device.

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Originally Posted by twistedtree View Post
Yes, it's 250k (or whatever), but so what. It's fine for what it does.
But that's the problem. It's enough speed for what's allowed to run on it. Why are radars running on ethernet? Or why can't you share a chart server between plotters? Because they can't work at 250k! So, we're still stuck running 2 networks on our boats, plus wifi for those that take technology to the extreme with iPads, etc.

Quote:
Originally Posted by twistedtree View Post
Radar and fish finders are already all on ethernet, and I think it's better to focus on how to encourage standardization of those protocols on ethernet, standardize transport of N2K PNGs over Ethernet, and encourage its evolution.
I'm for that! And I have some ideas on how to accomplish it. Maintain the N2K architecture of 50 nodes, 8 bit addressing, etc. Simply define a generic encapsulation on IP, standardize on a port number, register it, keep the networks small and go ahead and mimic the broadcasts from N2K. For the nay-sayers that believe they need quality of service (QOS), implement diffserv code points to match the N2k priorities. In my professional opinion, a 400 times increase in bandwidth (100mbps) will solve any perceived QOS issues.

Quote:
Originally Posted by twistedtree View Post
And leave N2K for all the stuff that runs through the bilge and up the mast, etc. Proprietary cables are tolerable running to the few expose ethernet devices.

I also think the CAN bus structure is preferable for wiring a boat compared to a star wired ethernet. I definitely wouldn't want to have to home-run the wiring for all my current N2K devices. I had enough trouble pulling the backbone cable through the boat.
I'm hollering more about the lack of functionality and continuation of proprietary/expensive implementations. I dislike bus topologies, but I can live with that if the rest of the issues were solved.

Those who think troubleshooting problems in a bus or ring network is easy has never had to chase a hard problem. It's not always an electrical problem (damaged cable), the major problems are when one or more units are producing malformed frames or well-formed spurious packets that bring all other devices to their knees. An intelligent ethernet switch will refuse to transmit malformed frames. A quick look at the management on a switch can show you the devices spewing the most traffic. Yes, a star wired controller (ethernet switch) is a single point of failure, but you can buy an off-the-shelf model for less than you have invested in N2K connectors and tees, keep a spare. $50 a port gets you a model with POE for power to the sensors. Weatherproof cat5 cable can be had for ~25 cents/foot.

Being a realist, I know that N2k bus will be around for a while, but I know the price will drop if/when ethernet/IP becomes ubiquitous on boats.
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Old 02-02-2012, 20:39   #26
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Re: NMEA N2K - what's wrong with it?

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Firstly the are several waterproof Ethernet connectors. amp do a very nice one as is used on the Garmin. Network.

Secondly you obviously don't understand Ethernet and star hub based systems they are much more reliable then bus systems

It is also possible to have combinations of star bus topologies. So at least you can isolate parts of the network from each other.

Can was designed to be a cheap network in an era of expensive Ethernet. That's all changed, Ethernet is a better solution. Can offers few advantageous, most of which are not much use in a boat.
Actually, I understand it pretty well. Bus forms of ethernet disappeared a long time ago, and all current implementations are star wired with hubs or switches. My comment was about the practical issues of pulling wires through boats and actually doing the wiring. I think in most cases a bus topology is a LOT easier to physically build. My comment had nothing to do with which is more reliable or easier to debug.

And my point about waterproof media was about the issues of standardizing such a connection. Standards bodies made up of vendors are never going to agree to adopt a connector that some of them are using or producing and others are not because it would give an immediate advantage to their competitors. I spent a couple of years doing this with ANSI. You know the saying about the committee tasked with creating a horse? They came up with a camel. Now if RM, Furuno, and Garmin are already using the same waterproof ethernet media system, that would be a different story. Are they by any chance? I don't know.

So anyway, the reality is that N2K is waterproof in a standard way and ethernet is not, and that's an advantage for N2K. And having outfitted a boat with N2K and ethernet (Furuno in my case), I found building and extending the N2K media to be easier because in a boat you can't just string a wire or drop another one into a cable tray. It's freekin torture to get wires from one place to another in a boat and do it neatly, and it only gets worse as the cramped passageways get filled up with more and more wired. I think that's a clear advantage.

Now if we could erase the board and start again from scratch, and I were declared king of Ethernet for Navigation, I'd probably jump on ethernet too, but that's not where we are.
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Old 02-02-2012, 20:56   #27
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Re: NMEA N2K - what's wrong with it?

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Oh, is this thread just meant to bash N2K. Well, alright but I'm out of here then.

I do not see the practical use of this. You should put effort into getting N2K to work as good as possible, instead of trying to reverse the decisions made which is not just a little naive to pursue. NMEA nor the industry is waiting for you to tell them how to do their jobs.

In the mean time, you seem to have missed the new N2K switches which create star topology?

Also, Furuno uses the same waterproof Ethernet connectors as Garmin. These are actually standard, I even have them for bulkhead-mount.

ciao!
Nick.
Nick,

The problem is that if NMEA doesn't take the action to make N2k better, an innovator will and then become the defacto standard. The market can/will move things with or without NMEA standards.

You mentioned in another thread about web servers on devices for configuration/update. I don't see that happening on the current N2k (although there are successful implementations of IP over CAN). Modifying the current architecture to support IP would cost way more than scrapping it and adopting off-the-shelf stuff.

IMO, that's the corner NMEA has painted themselves into.
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Old 03-02-2012, 05:55   #28
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Quote:
Originally Posted by DotDun

Nick,

The problem is that if NMEA doesn't take the action to make N2k better, an innovator will and then become the defacto standard. The market can/will move things with or without NMEA standards.

You mentioned in another thread about web servers on devices for configuration/update. I don't see that happening on the current N2k (although there are successful implementations of IP over CAN). Modifying the current architecture to support IP would cost way more than scrapping it and adopting off-the-shelf stuff.

IMO, that's the corner NMEA has painted themselves into.
We don't need NMEA for Ethernet access to devices. Check out Furuno's AIS and WeatherFax NavNet devices. Just start your browser and access them. Especially the weatherfax is a very good webserver based product.

I don't want radar over NMEA. Same for sonar, video-cameras etc. So the only wish would be for compatibility among components of different manufacturers, like connecting a Furuno radome to a Garmin plotter. I can tell you tht this is not going to happen because of our lobby. It's gonna happen when they become the same company

ciao!
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Old 03-02-2012, 09:28   #29
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Re: NMEA N2K - what's wrong with it?

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The problem is that if NMEA doesn't take the action to make N2k better, an innovator will and then become the defacto standard. The market can/will move things with or without NMEA standards.
Go for it. That's how I retired early and bought a boat.

I think your thesis is pretty clear;

- Network everything with ethernet. Not just radar etc., but all the N2K stuff too including VHF, GPS, weather, trim tab indicators, rudder position, gyro compass, displays (MFDs all the way down to dedicated depth gauges), tank sensors, pressure sensors, temp sensors. The whole works.

- Build a web server into each and every device for management, updates, etc. That way they can all be managed via a browser.

- Standardize (via committee or defacto) the data exchange between all these devices so all data is usable by all devices. This would be like the N2K PNGs, but over ethernet. This would also include standardizing the stuff that's already on ethernet like radar, AIS, depth sounders, etc.

It would an interesting challenge to pull it off. Of course initially it would look like yet another proprietary solution, and it would be a challenge getting the likes of Airmar to recast enough of their sensors to gain critical mass so one could actually outfit a boat this way. On my boat I'd need Simrad's AP displays and computer to be available in this new form as well. But that's the challenge of a start-up - making chickens when you have no eggs.

Other, more technical concerns would be:

- Power. Presumably this would be powered with POE (power over ethernet), but I'm be worried that each node would use a lot more power than the N2K equivalent. A typical hub or switch draws in the 2-5 watt range (just an estimate on my part). In contrast, a 1 LEN N2K device only draws 0.6W, and a large portion of the devices in my boat (just using it as an example where I've made a point of getting everything over to N2K) are 1 LEN devices. At least on my boat it's critical that I be able to leave the N2K network alive while at anchor for GPS, weather, and anchor alarm, so power consumption really matters. Trippling it or more would be a real problem.

- Cost. I can't argue the low cost of consumer ethernet products, but a big part of that is driven by the massive volumes involved. Some of that volume benefits a comparatively small, niche market like boat instrumentation, but it won't be the same as consumer electronics. Parts pricing, even for the same parts, varies by volume. And other product specific components like plastics, assembly, packaging, have costs highly dependent on volume. Many N2K sensors probably have nothing more than a PIC inside them, where a device that also includes a web server will need more compute power and more memory, both of which cost $$, space, power, and cooling. I'm sure it could be made to work, but if it were me I'd want to study to cost structure VERY carefully.

- Topology: Maybe it's just me, but the thought of home-running all my device wiring would immediately end any further consideration of adopting an ethernet-based replacement for N2K. To over come that issue, you presumably would build mini hubs (or something along those lines) to be used in place of the N2K drop Tees. That way one could create the moral equivalent of a backbone by daisy chaining these hubs together, then connecting in devices at various convenient points around the boat. Or would to do it otherwise? Either way, I think it aggravates the power and cost issues.

These are probably all solvable, and that's the fun of a start-up.
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Old 03-02-2012, 10:22   #30
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Re: NMEA N2K - what's wrong with it?

This is a bit naive, but why not have NMEA require manufacturers to publish the format of any PGN sentences their equipment sends?

Like this gentleman has reverse engineered for his own devices, but without the reverse engineering and guessing.

Then there is no reason to 'limit features' or 'slow innovation' by prohibiting custom protocols, and it is a very low burden on the manufacturers to publish summaries of whatever internal documents they already have. Other manufacturers (or end users with N2K-Ethernet bridges) can then write their own software to interface with whatever devices they want to.

You could even end up with a Universal Translator box that sits on the bus and allows you to make random device A completely work with random device B, or have the web server inside that does the firmware upgrades and etc.

This could even be opt in, with a little "Open Protocol Star of Approval" sticker for any devices that have published protocols. Consumers may end up demanding, or seeing this as a feature, and thus forcing the hand of most manufacturers to do this. Since they know that any devices with this sticker will work completely with OpenCPN or whatever regularly updated software they have, or the little Universal Translator box...
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