NMEA0183 from Simrad AT10 to NASA SX35 DSC

[triplee23]

Hi,

I am trying to send GPS position data from a Simrad GO7 GPS Plotter to a NASA SX35 DSC through NMEA 0183. But unfortunately, I am not getting it to work.

Between the GO7 and the SX35 I have a Simrad AT10 NMEA200(SIMNET)/NMEA0183 converter. The AT10 has the following connections on the NMEA0183 side of the converter.

White RX(+)
Brown RX(-)
Yellow TX(+)
Green TX(-)

As I am transmitting NMEA sentences to the SX35, I am connecting the SX35 through the Yellow and Green wires.

The SX35 has the following connections.

Brown RX(+)
Red RX(-)
Orange TX(+)
Ground/TX (-) Shield

I have connected in the easiest possible way:

AT10 Yellow TX (+) to SX35 Brown RX(+)
AT10 Green TX(-) to SX35 Red RX(-)

It is simpy not working. I do not get the GPS position data to the SX35.

The SX35 can read $GPRMC and the AT10 converts $GPRMC at 0.5 Hz.

Anyone have any tips?

Thanks in advance,
Triplee

 

[bitbaltic]

Well, it sounds like it's correctly wired up, the baud rates should match on the 0183 side, and the pgns are all present on the N2K side to get what you want. So assuming there's nothing in the Go7 menu which turns the N2K port off, best guess is a faulty connection or part.

Have you had anything wired up to the Nasa VHF before (ie are you sure it works)?

Have you tried wiring something else which can receive 0183 to the output from the AT10 (ie are you sure its outputting data)?

Have you got the right version of the AT10 (the univeral AT10, and not the fast heading version)?

 

[triplee23]

Thanks for the reponse.

I assume a have the universal, there is nothing to indicate that I have the HDG version. I have a Simrad Wheelpilot connected to the AT10 Output and it is getting waypoint data from the GO7, this also indicating that the AT10 is working properly. This is what makes it so confusing, this simple connection between the AT10 and the SX35 is not working.

 

[earlybird]

I'd try, as a possible alternative, connecting the AT10 Green Tx(-) to the VHF ground/shield.
Just a suggestion!

 

[bitbaltic]

Well. The AT10 is obviously the right (universal) one and working properly if it's getting data to the pilot.

This means the problem is with the NASA VHF. It could be (as earlybird suggests) that there is a transcription mistake in the manual and the RX in pins are not the ones stated (this sort of thing does happen). Is there some menu or other to turn the 0183 port on or off, or alter baud rate? If none of the above I'd suspect that (as it seems an oldish VHF) perhaps there is a 0183 version problem (ie the AT10 is talking a later version of 0183 than the VHF can understand). But it's difficult to tell.

 

[triplee23]

Thanks for all the advice, both bitbaltic and earlybird!

You are completely right, apart from the GO7, this setup is close to it's retirement. The SX35 has a very simple menu and installation possibilities. I have not found anywhere (in manual or on the unit) the possibility to change baud rate and the specifications only state (related to NMEA):

1) GPS/NMEA: $GPRMC sentence is decoded. NMEA Checksum can be turned Off/On.
2) Data Output: DSC call formats can be sent to PC & printer using 4800 baud and standard Terminal program.

I am assuming that is receives on 4800 as it output is 4800.

I have not found anywhere to turn ON/OFF NMEA, only the possibility to turn ON/OFF displaying the GPS position data on the display. This is turned ON. I have even tried CHECHSUM ON/OFF, no difference.

I will give it a try, connecting AT10 Green TX (-) to VHF Ground/Shield

I also fear that the AT10 and SX35 NMEA0183 versions are incompatible.