Getting my Onwa and Raymarine talking to each other...

Sea Change

Sea Change

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I have an Onwa KP707 AIS and a Raymarine e97 MFD. Both are compatible with NMEA0183.

There are some differences in the wire colours on the two devices.

Any tips on how to identify which wires need connected to where? And will I have hours of messing about with settings afterwards?
 
So according to the Onwa manual, one of the wires is 'AIS out'. On the Raymarine manual, the various 0183 wires are labelled as combinations of in, out, positive, and negative. So nothing matches up.

Have to say it's all gobbledegook to me. I need to understand the absolute basics. I don't even know how many wires are supposed to be joined together...
 
Ok. I may be in danger of getting somewhere!

So am I right in thinking that I need two wires between the AIS and the MFD?

AIS has 'out +', and 'out -', which connect to the 'in +' and 'in -' respectively. I think.

The MFD can connect to more than one device which had certainly confused me a bit. Also the 'out -' on the Onwa is also the -ve on the power supply.
 
Sea Change said:
Ok. I may be in danger of getting somewhere!

So am I right in thinking that I need two wires between the AIS and the MFD?
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Yes
Sea Change said:
AIS has 'out +', and 'out -', which connect to the 'in +' and 'in -' respectively. I think.
Click to expand...
Yes
Sea Change said:
The MFD can connect to more than one device which had certainly confused me a bit. Also the 'out -' on the Onwa is also the -ve on the power supply.
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Common practice, no problem.

Make sure the MFD port you use is set to 38,400 baud.
 
Success! Temporarily linked the two plotters using some wago connectors. A bit of hunting through menus until I found the baud rate. And that was it. Really pretty simple.

I have to say, the Raymarine is much cleverer with the AIS data than the Onwa. Different icons for different types of boat, ones that pose a danger appear to come up in red. Probably nothing new to most people but it's a bit of a revelation to me!
 
So, moving from bench test to semi permanent installation...

I need to run power plus the AIS data up to the
new plotter at the helm.

If the AIS -ve from the Onwa is also the -12v power supply... then why isn't it the same at the Raymarine end?

Can I just run a three core cable up there, and split the AIS -ve off from the 12v -ve?

Or because one is data and one is power, will bad things happen?

I have three core on the boat... and could finish the job today if I do it that way.
 
Sea Change said:
If the AIS -ve from the Onwa is also the -12v power supply... then why isn't it the same at the Raymarine end?
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The answer is because NMEA-0183 implementations are a mess and many manufacturers don't follow the standard. Garmin is one of the worst offenders; it really should do better. Raymarine is better in this respect and follow the standard. Onwa doesn't look good.

Here's an explanation. The NMEA-0183 standard describes both the physical voltage levels to be used and the protocol which specifies the format of the messages. There are 4 major versions. Version 1 came out in 1983.

The voltage levels described in version 1 was that the data lines should use the same schema as RS-232 (Now TIA-232). That has a single wire for the data with its voltage levels describing the data bits relative to the device's ground, what you call the 12V negative, but is better known as 0V or ground. A version 1 device will have as a minimum a data in/out line, device + power and device ground. Data ground will be common with device ground.

A disadvantage of this hardware configuration is that it is prone to interference and ground loops. This is not much of a problem on our size vessels but is more so on larger vessels. To overcome this the NMEA changed the standard in version 2 to use voltage levels taken from RS-422 (now TIA-422). This has two lines for data : data+ and data- in addition to device + power and device ground. Neither of the data lines needs to be relative to anything else on the transmitting or receiving devices, only each other. It's the difference between the data lines' voltage levels that transmits the data bits. Interference on one data line will apply equally to the other negating its effect making it more robust in electrically noisy environments. After version 1 the standard specified an isolated receiver circuit so the transmitter and receiver don't need to have a common ground preventing ground loops. An example of this would be connecting a handheld GPS receiver with internal batteries to a boat 12V battery powered plotter with a version 2 style receiver. The grounds of the transmitter (the GPS) and the receiver (the plotter) will be completely isolated but the data transfer will still work.

As the standard evolved through its versions the format of the messages also changed - the protocol. This was by adding new messages, deprecating old messages or adding extra fields to the end of existing messages in a backwards compatible manner.

So this is where the manufacturers have messed up. What they have done is use the message format from the later standards but the electrical voltage levels from version 1. Why? Because it makes it slightly cheaper to manufacture. Garmin uses version 4 message format with version 1 voltage levels. It sounds like Onwa does the same.

Fortunately because version 2 onwards explicitly requires successful reception of messages transmitted with TIA-232 or TIA-422 voltage levels you can get away with connecting a version 1 style transmitter (data, 0V) to a version 2 and later (data+, data-) receiver without too much issue. You will have a lower noise rejection capability, but on our boats it should work.

The isolation on the receiver side of NMEA-0183 equipment is achieved using opto-isolators.
 
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Thanks... that was... comprehensive! I appreciate you taking the time but I'll admit it's all very new to me. I don't have any sort of background in electronics or IT.

I went ahead and ran a three core, with the '0v' splitting at the Raymarine end. And it worked.
 
Sea Change said:
Thanks... that was... comprehensive! I appreciate you taking the time but I'll admit it's all very new to me. I don't have any sort of background in electronics or IT.

I went ahead and ran a three core, with the '0v' splitting at the Raymarine end. And it worked.
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NMEA basic rule .... is that any wrong connection of the NMEA and its associated wiring should not cause damage. This is why you can literally touch wires to test if works or not .. once you find the combo that works - that's it.

Of course this does not mean you can start playing games with the power wires !!

ONWA connection is basic and TBH - if any problems - Alan at Aves Marine who is the ONWA main dealer in UK - is very good and helpful ...
 
The dream for me is a completely N2K boat. My Matsutec AIS and Yeoman plotter are 0183 and both work well, but other stuff is N2K. Once you’ve plugged in a few N2K connectors and seen devices instantly start chatting happily to each other you don’t look back favourably on messing around with tiny wires in choc-blocks.
Apols to OP - my post no help to him, just musing really.
 
fredrussell said:
The dream for me is a completely N2K boat. My Matsutec AIS and Yeoman plotter are 0183 and both work well, but other stuff is N2K. Once you’ve plugged in a few N2K connectors and seen devices instantly start chatting happily to each other you don’t look back favourably on messing around with tiny wires in choc-blocks.
Apols to OP - my post no help to him, just musing really.
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0183 ... no terminating resistors / bits of wire.

0183 ... always found it simple to touch wires to confirm - then connect. With the NMEA2WiFi and later NMEA4WiFi plexors ... feed all 0183 / ST in and let that send all out as WiFi / USB or 0183 stream ...

My old Lowrance was N2K based for the antenna ... I hated the antenna part ... thick wire .. stiff as ***** ..... terminating resistor ...
 
Refueler said:
0183 ... no terminating resistors / bits of wire.

0183 ... always found it simple to touch wires to confirm - then connect. With the NMEA2WiFi and later NMEA4WiFi plexors ... feed all 0183 / ST in and let that send all out as WiFi / USB or 0183 stream ...

My old Lowrance was N2K based for the antenna ... I hated the antenna part ... thick wire .. stiff as ***** ..... terminating resistor ...
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Fair enough- but have you tried setting up an N2K network on a boat? It was a revelation to me after 0183. Plug ‘n’ play.
 
fredrussell said:
Fair enough- but have you tried setting up an N2K network on a boat? It was a revelation to me after 0183. Plug ‘n’ play.
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Yes I have.

I admit it was early days with awful cables and stuff that made the job harder than it should have been.

For many years I have been used to using light supple cable for 0183 that I could lead through smallest holes etc.

Now with the plexors - I think I can safely pass on by N2K ...
 
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