I just connected my Garmin GPSMAP 478 to my Navman 7100 VHF radio to make full use of the radio's DSC capability. The experience was frustrating to say the least, so I thought I'd share it with others who might be using the same equipment and wondering how to interface the two. I'm not an electronics expert (but I have stayed at a Holiday Inn Express), so my experience may not be the best example of how to do this properly, but at least it seems to work.
Having checked numerous internet posts, I found contradictory information. While the Navman manual was helpful in deciphering the proper wiring, the Garmin manual did not label the colored wires according to their NMEA values (e.g., IN, OUT, +, and -), which I gather is the standard protocol for sending and receiving data between multiple electronic units.
I have a 2006 Bayliner 285 cruiser. The VHF radio was already installed at the helm when I bought the boat. I think many of these Bayliner 285 models come with the Navman radio already installed. The Garmin is a portable version which came with a power cable with a “cigarette lighter" plug on one end that I plug into the accessory socket on the helm for power. To connect the GPS and VHF radio, I needed two additional data cables – one for the radio and another for the GPS.
I could not find the Navman cable available for purchase on the internet, so I called them. The person I spoke to said the data cable usually comes with the radio when it is sold, but since I bought the boat used and the radio was already installed I didn't have the extra cable. He told me they don't sell these cables separately on line, but that they occasionally keep them in stock for customers who request one. Not only did he find one, he shipped it to me free of charge – talk about excellent customer service! Next, I was able to find the Garmin data cable (it is both a power and data cable) on the Garmin web site and ordered it.
Both the GPS and VHF connector cables have one end that plugs directly into their respective units and the other end is a collection of thin, insulated colored wires. Once I had both cables the trick was figuring out how to wire them together properly. Of course, it's not as simple as connecting the blue wire on the GPS cable to the blue wire on the VHF cable, because different electronic products have different color-coded wiring. That's when the confusion started.
The radio's DSC capability is enabled by receiving data from the GPS that allows the radio to display the boat's GPS coordinates on its screen and to transmit those coordinates in an emergency. Therefore, data must flow OUT from the GPS and IN to the radio.
The Navman 7100 installation manual has a wiring detail chart that shows which colored wires are used to connect to a GPS. There are four – two that send data and two that receive it. Since I wanted the GPS to send data to the 7100, I only attempted to connect the two VHF wires that receive data from the GPS… those are the YELLOW wire (NMEA IN +) and the GREEN wire (NMEA IN -).
So far, so good. But the GPSMAP 478 manual has graphics that indicate the function of each colored wire, as “Voice," “Alarm," “Data In," “Data Out," etc., and not “NMEA IN “ or “NMEA OUT." That meant I had to identify the two wires that would be the equivalent of “NMEA OUT +" and “NMEA OUT –". By process of elimination I discovered that the BLUE wire (labeled in the manual as “Data Out" is the NMEA OUT + wire and the ORANGE wire (labeled in the manual as “Voice (-)" is the NMEA OUT – wire.
Connecting the BLUE wire on the GPS cable to the YELLOW wire on the 7100 cable (+ to +) and connecting the ORANGE wire on the GPS cable to the GREEN wire on the 7100 cable (- to -) produced the desired results. When both the GPS and VHF are turned on, the VHF screen displays the boat's coordinates on the radio, which means the radio is receiving the necessary data from the GPS. I also noticed that when the clock on the GPS advances 1 minute, the time display on the VHF screen also advances 1 minute, so they appear to be in sync.
GPSMAP 478 Navman 7100 VHF
NMEA OUT + (Blue) ------------> NMEA IN + (Yellow)
NMEA OUT – (Orange) ----------> NMEA IN – (Green)
I can't vouch for any other GPS or VHF unit, but at least I hope this is helpful for those with similar electronic equipment to mine. Of course, even though it now seems to work, I can't swear I did this correctly. If I missed something important, I hope someone will point it out.
Good luck!
Having checked numerous internet posts, I found contradictory information. While the Navman manual was helpful in deciphering the proper wiring, the Garmin manual did not label the colored wires according to their NMEA values (e.g., IN, OUT, +, and -), which I gather is the standard protocol for sending and receiving data between multiple electronic units.
I have a 2006 Bayliner 285 cruiser. The VHF radio was already installed at the helm when I bought the boat. I think many of these Bayliner 285 models come with the Navman radio already installed. The Garmin is a portable version which came with a power cable with a “cigarette lighter" plug on one end that I plug into the accessory socket on the helm for power. To connect the GPS and VHF radio, I needed two additional data cables – one for the radio and another for the GPS.
I could not find the Navman cable available for purchase on the internet, so I called them. The person I spoke to said the data cable usually comes with the radio when it is sold, but since I bought the boat used and the radio was already installed I didn't have the extra cable. He told me they don't sell these cables separately on line, but that they occasionally keep them in stock for customers who request one. Not only did he find one, he shipped it to me free of charge – talk about excellent customer service! Next, I was able to find the Garmin data cable (it is both a power and data cable) on the Garmin web site and ordered it.
Both the GPS and VHF connector cables have one end that plugs directly into their respective units and the other end is a collection of thin, insulated colored wires. Once I had both cables the trick was figuring out how to wire them together properly. Of course, it's not as simple as connecting the blue wire on the GPS cable to the blue wire on the VHF cable, because different electronic products have different color-coded wiring. That's when the confusion started.
The radio's DSC capability is enabled by receiving data from the GPS that allows the radio to display the boat's GPS coordinates on its screen and to transmit those coordinates in an emergency. Therefore, data must flow OUT from the GPS and IN to the radio.
The Navman 7100 installation manual has a wiring detail chart that shows which colored wires are used to connect to a GPS. There are four – two that send data and two that receive it. Since I wanted the GPS to send data to the 7100, I only attempted to connect the two VHF wires that receive data from the GPS… those are the YELLOW wire (NMEA IN +) and the GREEN wire (NMEA IN -).
So far, so good. But the GPSMAP 478 manual has graphics that indicate the function of each colored wire, as “Voice," “Alarm," “Data In," “Data Out," etc., and not “NMEA IN “ or “NMEA OUT." That meant I had to identify the two wires that would be the equivalent of “NMEA OUT +" and “NMEA OUT –". By process of elimination I discovered that the BLUE wire (labeled in the manual as “Data Out" is the NMEA OUT + wire and the ORANGE wire (labeled in the manual as “Voice (-)" is the NMEA OUT – wire.
Connecting the BLUE wire on the GPS cable to the YELLOW wire on the 7100 cable (+ to +) and connecting the ORANGE wire on the GPS cable to the GREEN wire on the 7100 cable (- to -) produced the desired results. When both the GPS and VHF are turned on, the VHF screen displays the boat's coordinates on the radio, which means the radio is receiving the necessary data from the GPS. I also noticed that when the clock on the GPS advances 1 minute, the time display on the VHF screen also advances 1 minute, so they appear to be in sync.
GPSMAP 478 Navman 7100 VHF
NMEA OUT + (Blue) ------------> NMEA IN + (Yellow)
NMEA OUT – (Orange) ----------> NMEA IN – (Green)
I can't vouch for any other GPS or VHF unit, but at least I hope this is helpful for those with similar electronic equipment to mine. Of course, even though it now seems to work, I can't swear I did this correctly. If I missed something important, I hope someone will point it out.
Good luck!