NMEA2000, STNG and DeciveNet compatability - expert needed!

[skyflyer]

Following on from a previous thread I started and having trawled the archives for relevant information, I have managed to find out the following "facts" about this , but they might be wrong and they beg further questions, so can anyone straighten me up on the following:

1) Seatalk NG (STNG) is "NMEA2000 with an extra wire" True or False?
2) "The extra wire is the Seatalk wire"; if so, what does it actually do?
3) "STNG and NMEA2000 are directly compatible" True or false - is there an N2K-STNG lead?
4) "NMEA2000 is the same as DeviceNet" True or false? Is it just that the plugs are the same and the protocols used for data transfer are different or do they work identically?
5) NMEA2000 protocol is top secret so you cannot build an electronic device that will work with N2K without their permission?
6) DeviceNet protocol is open source (or in the PD) so you can build a device that outputs DeviceNet compatible data

Why do I want to know? Because I am building a box of tricks (as per previous threads) that reads the anlaog output of my masthead wind transducer and outputs NMEA0183 sentences which can be read by another NMEA0183 device. However i have to get it fed into an STNG network.

This can be done commercially of course by buying an Actisense NMEA0183-N2000 converter and using a Raymarine N2000-STNG lead. Just looking sty alternative options though and tying myself in knots trying to work out what works with what and how!

 

[mattnj]

1) yes - plus connectors stay on device so cables are much smaller (to feed through holes)
2) provides backward compatibility (only some devices)
3) yes
4) don't know
5) you can do what you want....but unless you pay for the spec...you have to reverse engineer. I have made a device that outputs onto nmea 2k and ng bus.

 

[ianj99]

Re Q4: Its the other way round - the connectors are different but the protocol and generic pgns are the same.
(You can buy an Actisense NMEA to N2k interface for connecting to an STNG bus and the only difference is it comes with an STNG to Device net adaptor cable)

I made an analogue to nmea interface for connecting an old Seafarer paddle wheel log (5 pulses per knot) but use the above Actisense interface to get it on my STNG bus.

 

[prv]

4) "NMEA2000 is the same as DeviceNet" True or false? Is it just that the plugs are the same and the protocols used for data transfer are different or do they work identically?

Re Q4: Its the other way round - the connectors are different but the protocol and generic pgns are the same.

I thought NMEA2k and DeviceNet connectors were the same (at least for a subset of DeviceNet)? The chap behind Panbo suggests buying cheap industrial DeviceNet hardware from eBay instead of marine-markup NMEA2k, which wouldn't make sense if they had different connectors.

Pete

 

[ianj99]

http://www.raymarine.com/view/?id=5536&collectionid=9&col=1617

I was referring to STNG to Devicenet/N2K, sorry for the confusion. ( the OP did mention he wanted to connect to a STNG network)

The various marine electronics manufacturers are allowed to use their own proprietary connectors hence the existence of the adaptor cables I.E. there is no guarantee that Devicenet conenctors would be found on any particular N2K device.

 

[mattnj]

just to confirm, I have a devicenet cable here and a nmea2k cable here (from a Garmin) and they are exactly the same and plug together.

 

[Martin_J]

Beware though.. DeviceNet defines the protocol/standard... and on eBay some are DeviceNet Mini connectors and some are DeviceNet Micro connectors... The Micro appear to be rather smaller than the NMEA2000 we use on board.

 

[Martin_J]

.. as to the wires in them.. They should all be the same.. Same colour cores, same size conductor, same thickness insulation so they can be spliced together quite easily.