NMEA 2000 not working unless power cycled

[bmoney2334]

He guys I have a tz3 12 on The boat and it’s hooked to the NMEA 200 back bone. Utilizing the Simrad Precision 9 compass for heading. And the Simrad Nac3 autopilot for nav function. When starting the tz3 up I’ll have to power cycle the NMEA 2000 backbone for the tz3 to see the other devices in the backbone. Has anyone seen this before. Won’t matter if I power the backbone then the tz3 or the other way around. I have to cycle the backbone power while the tz3 is powered up.

 

[Quitsa]

I would suggest you check two things. One is the voltage on the NMEA 2000 backbone. Where is your power tap? The other is whether you have the NMEA architecture correct in terms of drops and termination resistors. My guess would be low voltage, which I know can cause this issue from personal experience with my SCX-20, especially if the drop to the satellite compass is long. In my case, the SCX-20 is mounted on the tower sunshade and the drop is over 20 feet. I solved the issue by putting an isolated power tap closer to it.

 

[Sparky Wire]

I would make sure that the NMEA 2000 power breaker is ON before powering up your NavNet as well.

 

[Lim Jahey]

I would suggest you check two things. One is the voltage on the NMEA 2000 backbone. Where is your power tap? The other is whether you have the NMEA architecture correct in terms of drops and termination resistors. My guess would be low voltage, which I know can cause this issue from personal experience with my SCX-20, especially if the drop to the satellite compass is long. In my case, the SCX-20 is mounted on the tower sunshade and the drop is over 20 feet. I solved the issue by putting an isolated power tap closer to it.

NMEA 2000 drops should never exceed 6 meters.

 

[Quitsa]

NMEA 2000 drops should never exceed 6 meters.

That is the standard but here was no option in my case because of the length of the cable run up inside the tower leg.

 

[Johnny Electron]

The bus is not proper so you are likely to have intermittent problems. NMEA rules are there with reason. They make in-line terminations and other ways around allowing long runs to have proper termination. NMEA 2000 is easy, great and complex at the same time. It is rarely easy as they envisioned.

 

[bmoney2334]

NMEA back bone is configured as so.

Terminator on both ends. 5ts between the terminators. One for Simrad Nac3 - Ap Computer one for the Simrad Ap44 control head. One for power 12v supply one for the tz3 and one for the precision 9 compass. All drops are less than 6 meters.