C80 / AIS / M504

[CampDavid]

Installing a Raymarine AIS 250 to connect to a C80 and supply GPS data to my Icom M504.

I can not seem to obtain any GPS information on the M504. I have set the C80 to AIS 38.4 NMEA. Connected the radio to the 4.8 out NEMA from the AIS multiplexer.

I have checked the out put of the AIS with a volt meter and it appears that some signal is there.

I am at a loss to figure this out.

I also have a ST60 Multo Graphics just beside the radio, could I use the NEMA out from that to feed the radio?

Any thoughts or suggestions as I am ready to jump into the drink.

fletch

[Vyndance]

The GPS for the radio needs to come from the chart plotter.

[jstevens]

Fletch,
There are two issues with having the M504 get a GPS position.
One is GPS data on the 4800B NMEA network. You don't say what GPS your have. I assume it is a Raymarine SeaTalk GPS connected to your C80. Since you have set the NMEA baud for the C80 to 38400 to accommodate the AIS traffic, that cannot be the direct source of GPS data for the M504, as it only works at 4800B (AFAICT).
The AIS250 has a 4800B NMEA output. It is a NMEA multiplexer, which means it should pass on NMEA data from your C80 to the M504. Do you have the C80 NMEA output connected to the AIS250 38400B NMEA input?
The second issue is the GPS sentence the M504 is looking for. I'm not familiar with the M504, but most ICOMs are looking for the GGA sentence. They ignore the RMC and GLL sentences. I did check the M504A manual and it states that radio will accept the RMC and GLL sentences, so that should not be the issue, if the M504 is the same as the M504A.

So if your are trying to send GPS data to the M504 via the AIS250, you need to determine if the C80 is sending to the AIS250, rather than just receiving, and that it is sending GPS sentences to the AIS250.

The ST60 Multi display NMEA output could be a way to send GPS data to the M504, the manual on that instrument should tell you if it outputs GPS data on that channel.

John

[barnakiel]

As mentioned go into C80 NMEA Output Setup and make sure it sends the right sentence.

AIS will pick it up and send on to the slower port of the built-in multiplexer.

You can check if the data is there (at either stage) by plugging the wires into a PC and looking up the content.

b.

[bewitched]

A wiring diagram would be good as it's not really clear how every thing connects.

At a guess you have:

Seatalk from GPS to C80?

NMEA (4,800) from AIS unit to VHF

NMEA (38,400) from AIS to C80

NMEA (38,400) from C80 to AIS

And I'm assuming that you have position on the C80?

So, there are only two connections it can be: the 38,400 C80 to AIS or the 4,800 from the AIS to the VHF.

Make sure you don't have your TX and RX wires crossed - remember, unlike seatalk. NMEA is one way signal.

[CampDavid]

John

Raymarine 125 seatalk GPS
Radio connected to nema 4800 out from the AIS250
Set all nema sentences to off on the C80 with the exception of GLL
No luck
checked the nema 4800 out on the AIS250, getting a varied low voltage range, ( indicates some transmisson).

I purchased the M504 used and as such I am not certain if the GPS feature is working or not. Perhaps I should check the radio from an alternate gps source.

Other than that I am quickly running out of ideas.

The ST60 multi reads nema GLL in, so I guess I could unplug the seatalk and plug the nema 4800 in to the multi and see if it picks up the location, if so then I would know I had a good transmission. Then it must be the radio,

Make sense??

fletch

[CampDavid]

Bewitched

You are dead on the equipment and the connections, I will double check all wired tomorrow

[jstevens]

Fletch,
The GGA and RMC sentences are the most common GPS exchange sentences, so I would turn those on rather than the GLL. If that doesn't work and you can't get any help from Raymarine or ICOM, I would try connecting the AIS250 NMEA output to a PC. Use the HYPERterminal (unfortunately that product appears to have disappeared with Win7) to view the NMEA traffic. This will require connecting the AIS250 output to the COM port on your PC (if it has one) or using a serial to USB adapter.
I put together a web page on using the HYPERterminal to troubleshoot NMEA connectivity issues at Sailing Topics
It is probably more than a little out of date, but it may be of some help.

John

[Black Diamond]

I actually have a separate line coming from my autohelm (4800) to the VHF and it works fine. I have 38400 bi-directional into the AIS 650 and then low speed VHF coming from the autohelm as well to the AIS for heading information. I was advised that there were problems unless you did it this way.

Mine is an E80, AIS650, ICOM 504 and S3 Autohelm combination.

Rick
S/V Black Diamond
Hylas 49-047 Portsmouth, RI.

[goboatingnow]

What is theirselves of the autohelm to VHF NMEA line. There's nothing the autopilot can contribute that's useful to the VHF.

Dave

[Jentine]

Originally Posted by goboatingnow

What is theirselves of the autohelm to VHF NMEA line. There's nothing the autopilot can contribute that's useful to the VHF.

Dave

The S3 autopilot controller has NEMA + and - connections on the board. It is a good place to connect to the radio.

[Black Diamond]

Exactly, and you did not have to buy the multiplexer.

Rick

[jstevens]

The S3 course computer can provide GPS data to a VHF radio or other 4800B NMEA listener. Of course it must receive GPS data from a SeaTalk GPS or an NMEA GPS to generate the GPS data on the S3 NMEA output.
The ICOM radios (and I assume most others) look for the CGA sentence. According to the Raymarine S3 manual the course computer generates only the GLL sentence. However I have noticed that my S3 does generate the RMC sentence, contrary to the documentation.
AFAICT, the S3 still does not generate the CGA sentence required by my ICOM M402 VHF and M802 HF radios. I must supply the CGA from my C120 MFD.
Later model ICOM VHF radios may accept the RMC sentence. I doubt they accept the GLL sentence as it does not provide time (used by the radio to determine if the GPS position is out of date).
So the S3 course computer may provide the GPS data a VHF radio is looking for, but that would depend on the instrument network configuration (SeaTalk and NMEA).

Nothing is for certain.

John