Data Source selection with TZT2 15 MFD?

[eheffa]

I have two questions:

1. I am intending to install my new Furuno TZTouch 2 15 MFD, NXT radar via Ethernet Hub and interfacing with a newly installed NMEA 2000 network. This should happen in a few weeks and I hope to have all the appropriate equipment at hand when I tear into the new job.

I am currently running a Vesper XB-8000 AIS acting as a bridge between my NMEA 2000 and 0183 networks. It is connected to an Airmar H2183 Fast Heading sensorvia NMEA 2000 and interfaces via 34800 BAUD to the older 0183 Brookhouse iMux. I also have an Airmar 150WX tied in via 0183 to the iMux. (I plan to connect the 150WX via a NMEA 2000 cable in the new setup.)

Both Airmar sensors are currently sending the appropriate data but the Raymarine E120 is seeing both heading sources and flipping back and forth between them. I cannot get the E120 to discriminate or prioritize the heading input source. This won't matter much in a few weeks when I switch the E120 out for the Furuno MFD but I do not want to be encountering the same issue with the Furuno MFD.

I see that Airmar sells a ~$300! USD USB-NMEA 2000 bridge that would allow me turn off the Airmar 150WX heading data but this seems to be ridiculously expensive solution for such a simple task.

I see in the manual that the TZT2 Furuno MFD should allow me to select which data source to use for input. Can anyone confirm that this should work properly and thereby eliminate the need for the Airmar NMEA bridge?

Specifically, will I be able to prioritize heading data from the H2183 over the 150WX in the setup?

2. I have my Power tap to the NMEA 2000 fused (both sides with their own inline 4A fuses) and attached to a fuse panel. Apart from a nonspecific "Instrument" Breaker on my breaker panel I do not have a specific switch to turn off the power to the NMEA 2000 network. Would it not be sensible to have the NMEA 2000 on a switch?

Thank you for any advice or comments.

-evan

 

[Johnny Electron]

Evan,
I can assure you, the TZT2 will have no problem selecting your Airmar NMEA 2000 heading sensor to use as the primary source. We have a local boat using that exact compass. You do not need to turn off the heading in the weather sensor. The TZT2 will use the weather sensor as a secondary source of heading, if something happens to your primary source. When it comes to your NMEA 2000 bus power, it really is up to you. Many have it wired as you do. The problem with drawing the power with other items on the same circuit can be noise depending what those other items are.

 

[eheffa]

Thank you Johnny.

That's very reassuring regarding the filtering of data sources and this makes the most sense.

So far, I am not seeing any 'noise' on the NMEA 2000 circuit but it shares a common bus bar with the AIS, and a few other lower draw electronics. I will be on the lookout for that potential.

Cheers,

-evan

 

[eheffa]

So, I now have my system installed. (Furuno TZTOUCH 2-15, Furuno DRSD24-NXT Radar via Ethernet hub, & via NMEA 2000 Canbus: Vesper XB-8000 AIS, Airmar H2183 Heading sensor, & Airmar 150 WX Weather instrument.)

In my initial testing, I had the TZT2 sitting in front of the dash & had no trouble getting a GPS fix.

After final installation with the TZT2 unit fully inset into the dashboard (teak enclosure in a Nordic Tug 37 pilothouse) I had no GPS fix. I noted that there were no visible satellites on the TZT2 Skyview but I could see that Multiple satellites were visible to the Vesper antenna but it took 30+ mins to get a fix(?). I then tried to get the TZT2 to prioritize the Vesper AIS GPS output over other sources. This worked OK when I first tried it, but then the next day with a cold start, there was no fix after 30-45 minutes of me pulling my hair out trying to be patient.. I noted that with the TZT2 off, the Vesper would get a good fix but with turning on the TZT2, the Vesper would lose the previously established fix.

The Vesper GPS antenna was mounted inside the pilothouse just under a fiberglass /wood roof ceiling. I wondered whether this was degrading the signal so moved the antenna outside noting a significant improvement in signal strength. I then re-wired it to an exterior pilot house roof mount.

This now seems to give me a good fix but haven’t had a chance to see if it is a reliable setup from a cold start.

My local Furuno Dealer tells me that I will continue to have these problems unless I install a NMEA 2000 gateway to eliminate redundant instances. Really? I thought the MFD was supposed to select from multiple data sources without the need for more hardware...

(I can see the potential value in installing a dedicated NMEA 2000 GPS antenna for a more direct feed to the MFD but I do not expect to add any more devices to this network.)

Is a gateway really necessary?

Thank you for your consideration.

 

[Johnny Electron]

My local Furuno Dealer tells me that I will continue to have these problems unless I install a NMEA 2000 gateway to eliminate redundant instances. Really? I thought the MFD was supposed to select from multiple data sources without the need for more hardware...

Is a gateway really necessary?

No. If you can get and keep the AIS unit with a reliable fix, you should have no problem. If you did have any NMEA 2000 instance conficts; most are easy to fix by changing the instance number of the said device. This is done under your sensor list. (keyboard next to instance number). Maybe the dealer is concerned with redundancy. With the TZT2 unable to get a fix where installed, you are now 100% reliant on your AIS for GPS. AIS units are not typically good primary sources for position. Many do not put out the needed magnetic variation etc. If you don't have another good source it could be scary if that unit goes down. Normally if you have two of anything; it should be two sources of GPS, regardless of what you have provide it.

 

[eheffa]

Thank you Johnny.

This is very encouraging and helpful.

I have no problem with buying a separate dedicated NMEA 2000 GPS Antenna as it's such a critical part of the whole system and a little redundancy makes sense. (I was prepared to for this as I was expecting that the TZTouch might have trouble getting a good GPS signal where it is installed.) But I had also expected that the TZTouch should be able to use the Vesper XB-8000 as the Vesper has a dedicated GPS antenna reporting all the useful data one would want from a dedicated GPS antenna.

I'm glad to know that I can use the TZTouch to assign Instance numbers. As a matter of good network design, would it not be wise to just do that? i.e. assign a simple and unique number to every device on the Canbus NMEA 2000 network (0,1,2,3 etc.)

Thank you for your help. This is a great resource.

-evan

 

[Johnny Electron]

You will find some devices wont allow an instance change. It is normally only needed when you have two devices providing the same PGN. So if you have two heading devices both feeding the same heading PGN to the bus; they should be on different instance numbers. The TZT2 for example can not be changed from instance 0 but no matter how many you have it isn't a problem due to the design of how the system works. That is part of a much larger training course than can be accomplished here. NMEA offers great courses if you ever decide to move into becoming a full time tech.

 

[eheffa]

Great! This gives me plenty to run with now.

Much appreciated...

( & no, I won't be quitting my day job anytime soon; especially since I'm now the proud owner of that proverbial hole in the water...)

-evan