[TG] [TG11] ST2000 to Lowrance Elite 5 connection

[Tom - Raymarine - Moderator]

Hello JFD,

NMEA013 unfortunately isn't always straightforward.

You've said that the wiring is correct, but if you can let us know exactly how you have this connected then we will be able to give you more informed support. People very often make mistakes with NMEA0183, since terminology is not completely standard and terms can be confusing.

Can you also please confirm that your plotter's NMEA connection is set to the standard NMEA0183 4800 baud rate, not 38400 or something else (I believe this display supports multiple port speeds, but standard 0183 is always 4800 baud)?

Some common reasons why this might not work:

• Differential (RS422) versus single-ended (RS232-style) signalling. More recent versions of the NMEA0183 specification use RS422 differential signalling, but older devices (the ST2000+ was first introduced in 1999) use single-ended RS232-type signalling. Have you got an NMEA transmit +ve and -ve, or a +ve and ground/0V? The former is differential, the latter is old-style non-diff.
• Signalling voltage. Again, older specs used a much wider voltage range (as wide as +15V to -15V) than newer versions (from memory a 1.5V difference is considered valid.) You'd need an oscilloscope to see what your device's full signalling range is, but it might be too narrow to trigger the receiver in the ST2000+.
• Message content. Having the same message types (RMC, APB etc.) is one thing, but are all of the required fields populated in the messages, and are the data-valid flags marked as valid? You would need to be able to read the raw data in order to check this (e.g. using a USB-serial interface into a PC with some serial terminal software such as Teraterm) unfortunately. The ST2000+ isn't very fussy in its data requirements, it will need bearing-to-waypoint (this ought to be in magnetic since the ST2000+ is using a magnetic heading sensor), distance-to-waypoint, cross-track error and (probably) waypoint name.
  

A more certain connection, and a workaround if you can't get the 0183 working, would be to us a Seatalk1 - SeatalkNG convertor, which translates between NMEA2000 and the ST2000+'s Seatalk1. NMEA2000 is a lot less prone to the above sorts of problems than 0183 is, which is 1980's technology and long past due for retirement.

Regards,
Tom