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Old 05-05-2015, 03:53   #16
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Re: Simnet/NMEA2000 Problems "Bus Off"

Not clear to me what you refer to as N2K...shorthand for NMEA 2000??
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Old 05-05-2015, 03:57   #17
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Re: Simnet/NMEA2000 Problems "Bus Off"

Alctel...I have a number of other peripherals on the simnet buss...radar, depth sounder, rate compass, and the new GPS GS 25....all appear to be operating properly except the GPS...I still have to try the isolated battery to power the system...
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Old 05-05-2015, 05:12   #18
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Re: Simnet/NMEA2000 Problems "Bus Off"

Unused Tee connectors should not have terminators on them. There should be two terminators, and only two. One at each end of the backbone. All the vendors have documents that give an overview of how to wire up an N2K bus. Maretron has some good info too. If you are concerned about the open Tee connections, Maretron has plastic caps that you can use.
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Old 05-05-2015, 11:58   #19
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Re: Simnet/NMEA2000 Problems "Bus Off"

May not have been too clear in my explanation...I am only using simnet buss connectors into the simnet starter kit, which has 7 jacks for simnet cables...I have a termination plug at one end, and the power supply for the buss, in the other end...all of the rest of my equipment plugs directly into the remaining jacks...I have no T connectors at all...
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Old 05-05-2015, 12:11   #20
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Re: Simnet/NMEA2000 Problems "Bus Off"

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Originally Posted by Gumshoe View Post
May not have been too clear in my explanation...I am only using simnet buss connectors into the simnet starter kit, which has 7 jacks for simnet cables...I have a termination plug at one end, and the power supply for the buss, in the other end...all of the rest of my equipment plugs directly into the remaining jacks...I have no T connectors at all...
You need a terminator at each end. Your power connector hooks into the bus at a convenient location but near the middle of the bus would be ideal.

Yes, N2K is shorthand for NMEA 2000.

Edit: Just looked up the starter kit. I don't know how that is connected up as far as terminations go. Check your documentation or contact tech support.
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Old 05-05-2015, 12:31   #21
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Re: Simnet/NMEA2000 Problems "Bus Off"

appreciate the help...according to the installation manual, as long as you have equipment plugged into one end, the other end would need a term plug, which came with the kit...this must be right as all of the other peripherals appear to be working properly...its only the new GS 25 that I am have issues with...even after the latest update to the software for the NSE 8
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Old 05-05-2015, 12:57   #22
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Re: Simnet/NMEA2000 Problems "Bus Off"

I guess Simrad has gone away from the Simnet and are now using NMEA 2000 cable and connectors. I saw on Panbo that an engineer had commented about the cable not having proper shielding and the insulation was to thin. Scroll down to the comments. I don't know if that could have anything to do with your problem or not but thought I would mention it.

Panbo: The Marine Electronics Hub: N2K, cable mixing not a big woop
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Old 05-05-2015, 16:23   #23
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Re: Simnet/NMEA2000 Problems "Bus Off"

Thanks for the info...I read the info at Panbo, and they thought it could be an issue, but didn't site any specifics...oh, well...as it is, I just tested the GS 25 by direct connection of simnet cable to the Chartplotter without the Simnet buss attached...no joy...I still believe this is related to the GS 25 not being listed in set-up....I downloaded the update again, and reinstalled with same results...really annoying at this point and not getting anything worthwhile from the dealer..his answer "maybe I sold you a bad antenna...see if anyone at the yard will let you connect and test the antenna"....can't find anyone here with a system that will allow w/o alterations...
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Old 15-05-2015, 06:51   #24
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Re: Simnet/NMEA2000 Problems "Bus Off"

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Thanks for the info...I read the info at Panbo, and they thought it could be an issue, but didn't site any specifics...oh, well...as it is, I just tested the GS 25 by direct connection of simnet cable to the Chartplotter without the Simnet buss attached...no joy...I still believe this is related to the GS 25 not being listed in set-up....I downloaded the update again, and reinstalled with same results...really annoying at this point and not getting anything worthwhile from the dealer..his answer "maybe I sold you a bad antenna...see if anyone at the yard will let you connect and test the antenna"....can't find anyone here with a system that will allow w/o alterations...
Make sure you don't have a device instance problem. One of my original problems was that the network sometimes gets confused by devices even of different types with the same instance number. I assigned all devices on the network unique instance numbers and this solved a number of problems. You might try that. Make sure you then go through the sources selection routine after that -- Network > Sources > Auto Select, then check the list of sources and make sure everything is showing. If you have multiple devices of one type (like, two different GPS position data sources), you have to assign instance numbers and choose which one you want the network to be using.

If the network doesn't recognize your GS25 after giving it a unique instance number, then I would look first at how it's connected, then I would wonder whether the device is working properly at all. The Zeus Touch has built in GPS and the network might default to that, if you don't set a unique instance number for the GS25 and then CHOOSE THAT DEVICE as position data source.
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Old 15-05-2015, 07:58   #25
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Re: Simnet/NMEA2000 Problems "Bus Off"

You say that you have ONE terminator at one end of the simnet 7 port junction block, and the power cable at the other end.

Some of the Simnet power cables have terminators built into them, and some don't. I think it has to do with whether or not the very end of the cable is red or yellow, but can't remember for sure.

You need to be sure that your power cable is the type with an internal terminator. Otherwise you have a backbone that is terminated at only one end, and operation will be unpredictable.
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Old 16-05-2015, 06:44   #26
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Re: Simnet/NMEA2000 Problems "Bus Off"

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Make sure you don't have a device instance problem. One of my original problems was that the network sometimes gets confused by devices even of different types with the same instance number. I assigned all devices on the network unique instance numbers and this solved a number of problems. You might try that. Make sure you then go through the sources selection routine after that -- Network > Sources > Auto Select, then check the list of sources and make sure everything is showing. If you have multiple devices of one type (like, two different GPS position data sources), you have to assign instance numbers and choose which one you want the network to be using.

If the network doesn't recognize your GS25 after giving it a unique instance number, then I would look first at how it's connected, then I would wonder whether the device is working properly at all. The Zeus Touch has built in GPS and the network might default to that, if you don't set a unique instance number for the GS25 and then CHOOSE THAT DEVICE as position data source.
Reading this it implies that 'assigning' an instance number is global to the network. AFAIK, the instance number is only used internally by the device you are programming. I could be wrong, as Navico could have a proprietary way of making this work globally for all devices on the network, but I don't believe there is any N2k standard way to do this.

Example: (2) GPS (labeled A and B). MFD 1 could be set to prefer GPS A while MFD 2 could be set to prefer GPS B. But MFD 1 could not set which GPS MFD 2 prefers.

Am I missing something?
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Old 16-05-2015, 20:17   #27
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Re: Simnet/NMEA2000 Problems "Bus Off"

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Reading this it implies that 'assigning' an instance number is global to the network. AFAIK, the instance number is only used internally by the device you are programming. I could be wrong, as Navico could have a proprietary way of making this work globally for all devices on the network, but I don't believe there is any N2k standard way to do this.

Example: (2) GPS (labeled A and B). MFD 1 could be set to prefer GPS A while MFD 2 could be set to prefer GPS B. But MFD 1 could not set which GPS MFD 2 prefers.

Am I missing something?
It's complicated, unfortunately, and that's part of the problem.

Each N2K device presents its "name" on the bus. The "name" is actually a bunch of different things that when taken as a whole, are guaranteed to be unique. It consists of the device type, manufacturer name, a name assigned by the manufacturer, and a device instance number. Any other device can pick who it wants to listen to based on this unique Name. When you configure many devices, they will list the Names of other devices on the network and let you pick which one to use as GPS, heading sensor, etc.

The device instance is part of the name, but it is used differently by different manufacturers. According to the N2K spec, the device instance number MUST be programmable on all devices. How you program it is unspecified, but there must be some way. One problem is that not all devices allow for programming of the device instance number, even though they are certified devices, and even though it's mandatory in the spec. This is a glaring hole in the N2K certification process.

The other problem is how different manufacturers use the device instance number. Some couldn't care less about it. This is perfectly allowable operation since all devices are still uniquely identifiable by virtue of their serial number even if they all have device instance set to zero. These manufacturers see no value is making device instances programmable. Furuno appears to be in this camp.

But other devices ONLY use the instance number to differentiate between like devices, and as such are completely dependent on other vendors correctly implementing programability. Maretron falls into this camp. If you have two depth sounders, or two GPSs, or two heading sensors, the only way Maretron products can tell them apart is if they have different device instance numbers. Mareron is not able to differentiate between devices even if one's name is "GPS200" and the other is "GS25".

Oh, and don't confuse Device Instances with Data Instances. They are totally different things.

With a more rigorous standard and more rigorous certification testing this could be resolved, but NMEA seems to have a totally limp dick on both fronts.
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Old 16-05-2015, 22:00   #28
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Re: Simnet/NMEA2000 Problems "Bus Off"

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Originally Posted by DotDun View Post
Reading this it implies that 'assigning' an instance number is global to the network. AFAIK, the instance number is only used internally by the device you are programming. I could be wrong, as Navico could have a proprietary way of making this work globally for all devices on the network, but I don't believe there is any N2k standard way to do this.

Example: (2) GPS (labeled A and B). MFD 1 could be set to prefer GPS A while MFD 2 could be set to prefer GPS B. But MFD 1 could not set which GPS MFD 2 prefers.

Am I missing something?
Navico devices have centralised source selection, so you cannot do this if MFD 1 and MFD 2 are both Navico.

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Old 17-05-2015, 06:30   #29
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Re: Simnet/NMEA2000 Problems "Bus Off"

OK Folks, here is the resolve...after pulling all the equipment, and using another system, I concluded that both my old GPS GS15 antenna and its original cable, as well as the new GPS GS25 antenna and its associated cable were both working (I laid the antennas on my instrument panel in the aluminum pilothouse and still received 12 strong channels)...voltage checks to all equipment were on the money...the monkey wrench in this entire effort was a failure on my part to realize the amount of electrical noise created by a 24-12 volt (The Appelberg is a isolated 24volt system) reducer that was installed to power the Simnet Joiner even though voltage checks indicated no issue...of course even a digital volt meter doesn't reflect dirty electrons flowing around anywhere . I have a number of these reducers throughout the boat that operate various devices without issue. And after review, I realize that none of those devices deal with digital equipment, just analog devices, charging, and mechanical devices. So, after checking the power source from the fellow that helped me check out my two antennas, I came back and reinstalled everything and removed the voltage reducer from the Simnet Joiner and connected directly to a 12v AGM battery....I thought I was at a 4th of July parade when I turned the ChartPlotter on ...everything shows up and everything is working...Woo Hoo!! I have yet to follow up with checking the instance settings with both antennas installed, but will do so. The current draw on the Simnet Joiner is so low (130ma), even with everything active, that I will probably use the 85ah AGM battery and charge it when necessary, and yes I do have a identical back-up battery!! The "Buss Off" statement is no longer displaying on any of the equipment pages.
PS...I was told by a industry insider that we have to give Simrad/Navico a little slack when it comes to the Simnet plugs and jacks that work just fine...apparently they were designed 3-4 years BEFORE NMEA got around to developing the standard that is now used today, and which Simrad/Navico have adopted.
Can't thank everybody enough for all the recommendations and suggestions in helping me resolve this. It is the reason I have joined the live-aboard/boating community...thanks again skipper Seal and his retired Swedish Sea Rescue Ship the AE Appelberg
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