TZT2 15v power via Multi cable

[NickT]

Just fitting a new TZT2. First time with nmea 2000. I assumed wrongly that the TZT2 would power the can bus. I have reread the installation manual and it says the white/red, and white/black cable on the multi cable gives 15v to power the can bus.
I have no volts at the white/red and white/black.
Do I need to turn something on? All the other system is up and running ok just no can bus.

 

[Taniwani]

The Red/White and Black/White are a power INPUT. And you need to have some 12V source to supply power to the NMEA2000 bus. Typically with a power cable that goes into one of the T-connectors on the backbone. The TZT2 gives you an option to 'safe' a T-connector and a power cable, by letting you input 15V on that point and it will then pass power to the NMEA2000 backbone.

I guess that they labeled it with 15V as it is likely diode isolated so that power coming from the backbone doesn't appear on those leads and can't be shorted.

So if you put ion 12V on those wires a little less will show up on the NMEA2000 backbone which will likely still be in the range of the NMEA200o spec. Still I'd recommend that you feed the NMEA2000 backbone separate if you have a spare T-connector slot and the a proper power cable.

 

[NickT]

Hi,
Furuno must have got their TZTL12F installation manual wrong!
I quote section 2.3
Use MULTI cable for the event switch, external buzzer, contact alarm and to supply power to the CAN bus. The connector has 11 wires. Use the table below for reference when connecting the MULTI cable.
Nothing about input?

 

[Taniwani]

That's how I read it too at the first glance. But if you look at the Interconnection Diagram' at the end of the installation manual, you will see that these wires are labeled NET-C_IN and NET-S_IN.

I think they meant to say that these wires allow you to supply power to the CAN-BUS through the TZT2.

 

[Johnny Electron]

I quote section 2.3
Use MULTI cable for the event switch, external buzzer, contact alarm and to supply power to the CAN bus.

The wording is correct but maybe not clear to those unfamiliar with NMEA 2000. When you connect external power to those input wires it indeed "Supplies power TO the CANbus" . The CANbus being the 5 pin NMEA 2000 connection. The power you place on the wires is fed out to the Canbus instead of you powering your bus from a typical bus power tee. It is a nice option but can be confusing to some. I will ask Japan if they can't come up with wording that is simpler to understand. Using that method instead of a power tee is only allowed for small buses with a bus draw under 1 amp. It say "15v" because NMEA power standard is 9-16v and I guess they wanted to avoid even more confusion by listing 12v (which is more common for one to have). Technically anything in the range would be good but using 9v would be pointless because the time it goes down your wiring it will be below standards. Better to choose higher than lower in that voltage range.

 

[NickT]

OK,
Thats clear. Thanks for your help.