tag:blogger.com,1999:blog-3086978695636448584.post1904375126688193907..comments2024-02-26T18:53:40.799-05:00Comments on Adventures of Tanglewood: NMEA 2000 Standard CommitteePeter Haydenhttp://www.blogger.com/profile/06586816406202219798noreply@blogger.comBlogger14125tag:blogger.com,1999:blog-3086978695636448584.post-68664366514456392942015-12-06T14:24:51.645-05:002015-12-06T14:24:51.645-05:00Kees, your comment here along with our email excha...Kees, your comment here along with our email exchange finally caused the light bulb to go off in my head. We are talking about different "Instance" numbers. N2K has Device Instance Numbers and Data Instance Numbers. They are similar, but different. Device Instance Numbers only get exchanged at network config time or if a device specifically queries for it. A Data Instance Number isPeter Haydenhttps://www.blogger.com/profile/06586816406202219798noreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-69547084840823339192015-12-05T09:39:22.280-05:002015-12-05T09:39:22.280-05:00Note that most PGNs don't even have an instanc...Note that most PGNs don't even have an instance ID field so the Maretron position is flawed, to say the least. Many many devices do not need an instance ID whatsoever.<br /><br />The idea is that a PGN will include an instance ID field if ONE sender can report on MULTIPLE thingies.<br /><br />So a Depth PGN 128267 does not include an instance ID, because a depth sensor will typically only Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-42529942328927243512015-03-21T17:36:35.666-04:002015-03-21T17:36:35.666-04:00I don't think I'm confused at all about wh...I don't think I'm confused at all about what the issues are. Maretron depends on Instancing to select devices, and devices do not consistently implement instancing. It's black and white. Yes, lots of times it can be worked around in one way or another, but that doesn't make the issue go away, just the symptoms. Heck, I've gotten the systems that I've built to work by Peter Haydenhttps://www.blogger.com/profile/06586816406202219798noreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-38545839550069136462015-03-21T14:18:00.725-04:002015-03-21T14:18:00.725-04:00Peter, you can change the Device Instance of an Ai...Peter, you can change the Device Instance of an Airmar 200WX, so the Check-Mate scenario is false.<br /><br />(You can also turn off individual PGNs coming out the 200WX, like Heading, if you don't need it.)<br /><br />Moreover, most displays don't have a problem if you just leave redundant sensor Instances as they are.<br /><br />I've used the Airmar PB200 (predecessor to the 200WX) Ben Ellisonnoreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-41646194994204060382015-03-21T10:33:10.197-04:002015-03-21T10:33:10.197-04:00For our readers, Ben's last comment about True...For our readers, Ben's last comment about True headings is a carry-over from a discussion about Class A AIS and its requirement for an external True Heading input. http://www.panbo.com/archives/2015/03/amec_camino_701_class_a_ais_first_with_a_nearly_complete_nmea_2000_interface.html<br /><br />For now, let me bring this back to the Blog subject which is some of the loop holes in the NMEA 2000Peter Haydenhttps://www.blogger.com/profile/06586816406202219798noreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-14787369515878822682015-03-21T08:21:07.851-04:002015-03-21T08:21:07.851-04:00Peter, I believe that most MFDs and N2K instrument...Peter, I believe that most MFDs and N2K instruments will compute True Heading if they see Magnetic Heading and Variation on the network. And typically they output the True Heading value as well as display it (though sometimes output is an option you have to invoke).<br /><br />I'm far away from my boat now to double check this, but I'm nearly positive that my Simrad network with only an Ben Ellisonhttp://www.panbo.com/noreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-47930960569890752742015-03-20T20:37:12.475-04:002015-03-20T20:37:12.475-04:00Thanks for the reminder on that. I don't have...Thanks for the reminder on that. I don't have a DSM250 anymore and had forgotten about that capability.<br /><br />But it's only suitable if you want the DSM250 to completely ignore a particular device, right? And that capability doesn't exist in N2KView which is what I'm using now. Unless I'm totally missing something, Instancing is the only way to differentiate between Peter Haydenhttps://www.blogger.com/profile/06586816406202219798noreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-75223568850789106342015-03-20T14:47:45.941-04:002015-03-20T14:47:45.941-04:00Peter, If you have two compasses on your network a...Peter, If you have two compasses on your network and don't want to see one on your Maretron display, just go to Configuration/Device Selection and turn off the compass you don't want to use. It takes seconds and does not involve Instances.Ben Ellisonnoreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-54883196412002441502015-03-15T18:13:37.623-04:002015-03-15T18:13:37.623-04:00Ben, I just re-read my blog post and see that I ha...Ben, I just re-read my blog post and see that I have learned more (that's always a good thing) since writing it. In particular I now realize that it's really only Maretron who are 100% dependent on Device Instance numbers (and Data Instance Numbers too) to differentiate between data sources. Other products can differentiate even if all devices have instance number zero.<br /><br />Peter Haydenhttps://www.blogger.com/profile/06586816406202219798noreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-51239060412495124892015-03-15T17:58:50.779-04:002015-03-15T17:58:50.779-04:00Hi Ben,
True, and not true. In many ways the pro...Hi Ben,<br /><br />True, and not true. In many ways the problem is Maretron who have elected to use instancing as their means to select between devices of the same type. With their display products, two GPSs or two heading sensors or two rudder indicators MUST have different instance numbers if you want to spell out which to use. This can happen if you want to display both devices' data atPeter Haydenhttps://www.blogger.com/profile/06586816406202219798noreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-86208992298426855882015-03-15T17:03:47.594-04:002015-03-15T17:03:47.594-04:00Sorry, but I think you have Instances pretty mixed...Sorry, but I think you have Instances pretty mixed up. They're important if you want to use two or more of the same device type simultaneously, but not for selecting one device of several redundant ones to use.<br /><br />For example, if you have N2K engine sensors on two engines, one is typically Instance 0 and the other Instance 1. But nearly every display on my quite mixed up N2K networks Ben Ellisonhttp://www.panbo.com/noreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-42871603258786446332015-02-17T00:26:09.197-05:002015-02-17T00:26:09.197-05:00NMEA sounds just as dysfunctional and illogical as...NMEA sounds just as dysfunctional and illogical as our present Congress :).Wilnoreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-21026771770152937822015-02-15T19:38:46.561-05:002015-02-15T19:38:46.561-05:00Very instructive!
THANKS!
Norm
Quiet Company
Gre...Very instructive!<br /><br />THANKS!<br />Norm<br /><br />Quiet Company<br />Great Harbour GH47Quiet Captainhttps://www.blogger.com/profile/12785537719354264651noreply@blogger.comtag:blogger.com,1999:blog-3086978695636448584.post-5491436287417084142015-02-14T18:08:29.197-05:002015-02-14T18:08:29.197-05:00Sorry for your troubles Peter but thank you for sh...Sorry for your troubles Peter but thank you for sharing your experience. it sounds as though many folks are betting their life navigating with inferior or flat out non functional equipment. Sad. Anonymoushttps://www.blogger.com/profile/06751343838914014429noreply@blogger.com