Navtex NX300 - GPS Data Input

[flippercarson]

Hello All,

This is my first post in the forum and I hope I can find the info I'm looking for!

I have a Navtex NX300 and want to feed it GPS data from my NMEA0183 network. The wiring diagram on page 61 of the manual suggests that White + and Blue - should be the wires I use, but it's not working. I've also spoken with Furuno tech support (who were very nice but ultimately unable to resolve the issue).

Will the NX300 accept standard NMEA0183 input data OR will it only accept RS232 data and not 422 spec NMEA data? Do I need a RS232 to 422 converter? Has anyone else successfully fed their NX300 data from a standard NMEA0183 network?

I feel like I must be missing something here, but I'll be darned if I can get this thing to accept GPS info. Any help would be appreciated. Thanks.

 

[Johnny Electron]

Unlike NMEA 2000, NMEA 0183 isn't exactly what would be called a "Network".

NMEA 0183 historically could be transmitted at RS422 or RS232 signal levels. It wasn't until recent times that RS422 became the established level for 0183. In the case of the NX300, it talks at Serial PC level (RS232 level) 0183 as indicated in the interconnection drawing below.

Do you have an RS232 level source? If not, then to properly connect a RS422 source, you would need a level converter (RS422/RS232). I am guessing that is why you are having difficulties. You don't put diesel gas in an unleaded car, nor should you put RS422 0183 into a RS232 0183 unit. The level converter or the RS232 source of GPS would be connected to the SG (Signal Ground) [BLUE} and the RD (Receive Data)[GREEN] wires to receive and process the GPS data on port 1. If receive port 1 is use, you can always use RD2 (receive data 2) instead. [WHITE]

 

[flippercarson]

Thanks for the reply, Johnny. It seems you confirmed my diagnosis. I've ordered the following converter from Amazon.

https://www.amazon.com/gp/product/B0196 ... UTF8&psc=1

I've also ordered this cable end.

https://www.amazon.com/gp/product/B071D ... UTF8&psc=1

My plan is to attach the leads from the Navtex unit to the cable end (trying to get the pin assignments right) and then plug it into the converter. On the other end of the converter I should be able to do a standard NMEA0183 connection if I understand it all correctly.

I don't suppose you'd know the proper pin assignments would you? Am I on the right track here? Thanks.

 

[flippercarson]

Johnny,

I've found the following for 9-pin pin assignments.

https://www.stratusengineering.com/rs232-9-pin-pinout/

From this , I'd get Green to pin 2, Yellow to pin 3, and Blue to pin 5. Does that seem right?

 

[Johnny Electron]

If you want the connection to be bi-directional it would be wired like this...

NX300 to 9-pin Serial

BLUE -- Pin 5
YELLOW -- Pin 2
GREEN -- Pin 3

I also recommend that you place two jumpers on that same end of the 9 pin serial to loop flow control and error correction.
Jumper Pin 4 to 6
Jumper Pin 7 to 8

If you only want to single direction (GPS into the NX300 only) you can leave off the Yellow wire (pin 2 of the 9 pin serial)

 

[flippercarson]

Thank you, Johnny.

On a side note, I can't believe most boaters would have the technical skill to solve this issue or make this connection, especially when Furuno tech support wasn't able provide this info. Perhaps most interested boaters are either using old Furuno equipment tied together with RS232 level connections, or they are simply not connecting position information. Either way, this would certainly make a good sticky note as it relates to the NX300.

Thank you again. I'll report back.

 

[Johnny Electron]

Most don't connect up position on this unit. Due to signal strength, it normally will only pick up the closest station so GPS is sort of a GEEWIZ thing.

 

[flippercarson]

Johnny,

Unfortunately, I don't have good news to report. I simply can't get the Navtex Unit to accept data. I've tried two different NMEA0183 sources and have confirmed that their output is working fine. I connected the converter as directed (actually, I tried multiple different configurations and permutations) and still no joy. After many hours and more money thrown at this, the unit just doesn't want to communicate.

Is it possible or probable that the I/O circuitry on the Navtex unit is faulty? Are there voltages I can check on the leads coming from the Navtex unit that might provide some insights? Any more suggestions would be welcome.

 

[Magnetron]

You need a GPS Navigator like a GP-31/GP-36 or something that outputs RS-232C according to the manual.

ref. https://furunousa.com/-/media/sites/fur ... _52512.pdf

- Maggy

 

[Johnny Electron]

If you believe the input port to be damaged, it can be sent in for evaluation. Overall it is rare to see input ports to go bad. It is more common to see output ports get damaged than input ports but it is possible.