Converting RS232 or USB to NMEA or Sea Talk

[hwturner]

I have an older AIS Class B system made by ACR and Nauticast. It is designed I believe to work with a windows laptop. It has up to this point worked great with Nobletec software. I recently added a Raymarine C-95 Multi functional display and want to get the AIS data on this unit which is at my helm. The laptop being below I thus far cannot see my AIS data while driving. The AIS unit has an RS232 output, which I currently convert to USB for the computer, but does anyone know a way to get the RS232 data converted to NMEA? My C-95 has the ability to connect to NMEA or SeaTalk.
Thanks,

[smac999]

it already is nmea. just connect the wire from the ais to the chart plotter... your laptop was reading nmea.

you either need to cut the plug off (if you don't want to use the laptop any more) or buy a serial cable, and plug it in, and cut the other end off, and wire to plotter.

[muttnik]

In this recent thread the poster is connecting an AIS unit with an rs 232 output to a raymarine plotter (though an older one). It works, despite the fact that the physical connection (ie rs232 rather than 422) is not conformant to the later NMEA-0183 standards. The same should go for yours.

Your mission, should you choose to accept it, is to connect the transmit data pin ("TXD", pin 3) on your rs232 connector to "NMEA in +" connection on the plotter and the ground pin ("GND", pin 5) on the rs232 connector to the "NMEA in -" connection which is the pair of the "+" connection you used. Use the input only pair (orange/white and orange/green) if there's no pressing need for bi-directional communication.

You can buy a 9 pin d shell from radio shack and make up a cable, or as smac999 suggested, chop the end off an existing serial cable. If doing the former, use your favourite search engine to find a diagam for "DB9 pinout", but beware that it's easy to get confused between male and female, front and rear views of the connectors. pin 3 is easy to spot though and you've got a 50/50 chance of getting pin 5 the right way round by chance alone. If chopping the end off a pre-made cable, use a multimeter to find out which pin ends up in which wire end.

Anyone else think that raymarine missed a trick by building all this wireless and network stuff into the new plotters, but then neglecting to think that people might find it convenient to send old-style NMEA data over a network rather serial lines?

[undercutter]

Originally Posted by muttnik

Anyone else think that raymarine missed a trick by building all this wireless and network stuff into the new plotters, but then neglecting to think that people might find it convenient to send old-style NMEA data over a network rather serial lines?

I think the concept is to force you to purchase all the rest of the equipment that won't network with their new plotters. $$$$$

When I was in Boat Lagoon, Thailand this spring, Octopus Marine had 2 in the box new E140W plotters that were never installed as the owner they were ordered for wanted to have only the latest and greatest equipment installed on the boat. Don't know the details but I understand that in the end he replaced a lot of other components to match his new plotters.

As we already have E140W plotters we had no interest but a great deal for someone who would want them.

[stmbtwle]

Yes I've had the same problem. My laptop reads the GPS (NMEA 0183) just fine and while my autopilot reads the GPS it cannot read the laptop. The autopilot on my previous boat (pre-Seatalk) had no problem.

[goboatingnow]

Originally Posted by muttnik

In this recent thread the poster is connecting an AIS unit with an rs 232 output to a raymarine plotter (though an older one). It works, despite the fact that the physical connection (ie rs232 rather than 422) is not conformant to the later NMEA-0183 standards. The same should go for yours.

Your mission, should you choose to accept it, is to connect the transmit data pin ("TXD", pin 3) on your rs232 connector to "NMEA in +" connection on the plotter and the ground pin ("GND", pin 5) on the rs232 connector to the "NMEA in -" connection which is the pair of the "+" connection you used. Use the input only pair (orange/white and orange/green) if there's no pressing need for bi-directional communication.

You can buy a 9 pin d shell from radio shack and make up a cable, or as smac999 suggested, chop the end off an existing serial cable. If doing the former, use your favourite search engine to find a diagam for "DB9 pinout", but beware that it's easy to get confused between male and female, front and rear views of the connectors. pin 3 is easy to spot though and you've got a 50/50 chance of getting pin 5 the right way round by chance alone. If chopping the end off a pre-made cable, use a multimeter to find out which pin ends up in which wire end.

Anyone else think that raymarine missed a trick by building all this wireless and network stuff into the new plotters, but then neglecting to think that people might find it convenient to send old-style NMEA data over a network rather serial lines?

You can get NMEA0183 into most raymarine plotters. Nmea0183 is RS422 levels so not directly compatible with Rs232

[stmbtwle]

Originally Posted by goboatingnow

You can get NMEA0183 into most raymarine plotters. Nmea0183 is RS422 levels so not directly compatible with Rs232

Still not working for me. I installed a RS232-RS422 converter and connected the TX outputs to the NMEA input terminals on the Raymarine. I'm know I'm getting sentences to the Raymarine but it's still giving me a "no data" message. It works fine using the Garmin on the same terminals. I even copied the sentences that the Garmin sends out, and programmed the laptop to send the same sentences.

Still no luck. I'll add an optocoupler as soon as it comes in.
Do I need to run a third (ground wire) from the converter to the Raymarine?
Thanks.

[Pandor]

Have you chang d the baud rate on your chart plotter connection? AIS baud rate is almost always 38,400 while standard NMEA is 4800. There should b an option to set the connection for regular or hi-speed

[stmbtwle]

This has nothing to do with an AIS but the GPS is 4800 and so is the laptop. The autopilot reads the GPS but not the laptop. It's got to be in the interface somewhere.
No I'm NOT connecting both at the same time. I disconnect one and connect the other. When (if) I get it working I'll install a selector switch.

[goboatingnow]

Garmin uses single sided comms. In effect one data wire and ground. Raymarine uses differential.

Just check your wiring. It’s almost certainly the issue. A ground wire will be needed with ray marine.

[stmbtwle]

Originally Posted by goboatingnow

Garmin uses single sided comms. In effect one data wire and ground. Raymarine uses differential.

Just check your wiring. It’s almost certainly the issue. A ground wire will be needed with ray marine.

I agree it's likely the wiring but it does have me stumped. The Raymarine has no problem reading the Garmin, nor does the laptop. The problem comes when I try to get the Raymarine to read the laptop. I've tried single-sided, and I've tried differential. Neither seems to work.

I ran a separate ground and also grounded the shield... still nothing. Analog voltmeter shows about +2 to -1 volts across the leads.


Finally I got a wild idea and REVERSED THE LEADS, so that the + lead from the computer is on the -NMEA terminal and vice versa. VIOLA! It works! Why, I still don't know. Any thoughts would be appreciated, maybe someone else can benefit.