[TG] [TG11] ST5000+. NO DATA error.

[Tom - Raymarine - Moderator]

Hi Dave,

I'm sorry to say that I could have answered that accurately when the ST5000+ was current or recently retired, but not now. All I can say is it would have complied with the NMEA0183 spec that prevailed at the time, which I am assuming would have been v2.x. A quick look at a spec of that sort of age says that there should be a minimum 2v differential between high and low lines, but that designs should be backwards compatible with earlier spec versions that used (roughly) 0V .. -15V as a Low and +4V .. +15V as a High.

Again, you'd need an oscilloscope to be sure of what was happening (PC oscilloscopes are very cheap nowadays, and not too hard to use), but it sounds pretty convincingly as if the signalling level is the cause of the problem. If there's no setup in the mux for this then you'd be down to either:

• replacing the mux
• building some new hardware, or sourcing some intermediate box that will step up the levels (perhaps an RS422->RS232 convertor might do the trick?)
• daisy-chaining multiple convertors, e.g. mux->NMEA0183-2000 convertor->Seatalk via our E22158 convertor (this seldom ends well, I only mention it to dissuade from it)
• looking at upgrading the pilot
• ...
  

I have to say, I can't stand NMEA0183. It's dot-matrix printer, VHS video, TV-remote-with-a-hardwired-cable generation technology that I am somewhat over troubleshooting. There are a lot of good reasons why all of us hardware manufacturers moved over to NMEA2000 many years ago and if there's any way for you to do the same, you'll save yourself some pain.

Regards,
Tom