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I have a problem interfacing my Weatherdock easyAIS with the Raymarine C70 chart plotter.

All this started because I wanted to sent the GPS position to my ICOM M802 (with DSC).

I previously used the NMEA interface on the Raymarine Autopilot computer for both the ICOM VHF and the easyAIS and it worked fine.

Now it won't work no matter what i do an now I am confused.

The easyAIS is wired up to the autopilot at 38400 baud and relies on the boat GPS which feeds into the C70 to give the AIS info on the screen.

My neighbor has his AIS transponder running so the signal is there. In addition there are several large commercial vessels in the port with AIS.

My VHF antennae for the easyAIS is mounted on the taga bar 2M above the water on the stern. I have tested the antennae with my ohm meter and it is fine.

This is what I have done so far:

1. I have connected the NMEA output from the easyAIS to the Raymarine computer NMEA(1) IN and then connected a pair from the NMEA(1) OUT to the C70 NMEA input. The output at the NMEA OUT is in the 2 to 3 millivolts range. The C70 shows no sentences in and no AIS options are available.

2. Connecting the eastAIS to NMEA(1) IN relying on the signal from the AP computer to the C70. Still the C70 shows No sentences in and no AIS.

3. I have bypassed the AP computer using a electrical joining block. The voltage at the C70 is 5.7 without variation. Again, the C70 shows No sentences in and no AIS.

4. I have switched the baud rate on the easyAIS to 4800 and the C70 and connected the ICOM HF radio to the NMEA via a connection block (without going thru the AP Computer) and the position and time shows on the HF. I realise that the C70 will not show the AIS at 4800 baud.

The C70 diagnostic tool reports no Rx sentences although there are plenty of Tx sentences from the GPS and other nav gear.

I am not sure that the easy AIS is still working but it was working before I changed the system and there is still the output of 5.7 volts.
I am sure that the solution is simple but I just don't get it.

Cheers
Sirromcd in Malaysia
 

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Your approach seems confusing too ! First, make sure your AIS output is working at some baudrate. Connect a RS-232 laptop input (should work although RS-422 is not 100% compliant to RS 232), open a terminal and find the correct bps combination. You should not go over next steps until you find the correct baudrate, stop bit lenght and parity; this way you grant your AIS is puting sentences out. Next, connect it directly to your C70 NMEA as your AP might not be bridging AIS correctly, no matter if worked before. The voltage you measure has almost no meaning as this is a pulse, and the RS-422 is indeed a current loop rather a voltage sensitive. Should be a simple matter of carefully approachung your system by following the data path in steps. Good luck .....
 

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Hi Negrini
Thank you for your input. Yes I was confused. I now have the AIS connected directly to the C70 (with the correct polarity) via the NEMA In.
The AIS is working I have checked the baud rate and all is fine there.

The antennae has checked out by testing with the VHF radio.

The AIS icon in the C70 still shows a cross thru it but that was the case when I initially installed the AIS.

At that time The system seemed to come alive when an AIS signal was received while we were underway.

I think this may be caused by the AIS alarm being turned off. However turning it on did not change the icon status.

I will do a test later today and keep you advised.

Thanks again for your input.
Sirromcd
 

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We have a Simrad AI 80 hooked up to an E-120 and have never had the little AIS icon without an X through it. Our Raymarine rep told us that some AIS units are really not compatible with the Raymarine software and that we might have some quirks with using something other than a Raymarine AIS.
We still get AIS symbols on the screen but the little AIS icon has an X through it.
 
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