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Old 09-12-2008, 09:07   #16
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Ok, my thought is this, the E85001 is a bridge. NMEA in and out on the PC side and Seatalk on the host side (if I remember correctly). In my system my E80 is sending all of the higher data rate data by Seatalk II (aka Ethernet). Only slow data, GPS position, depth, maybe windspeed and boat speed are on the Seatalk I bus (RS232). So..... I would think that a multiplexer is not needed unless you have multiple non-ethernet devices. Correct me if I am wrong (it happens).
If there is only one NMEA device going into the C-70 (typically, a laptop or an AIS receiver), a mux (multiplexer - combines data neatly) isn't needed. However, if you want a laptop and an AIS receiver, it's mux time for two reasons: 1) two talkers [laptop, AIS], 2) devices operating at different rates (Raymarine accepts NMEA at 4800 baud only, with the exception of AIS, at 38,400 baud). It's not good form to tie multiple listeners (laptop, EPIRB, etc.) to a single NMEA output port but it usually works.

I hope that clears up the mystery.
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Old 09-12-2008, 09:14   #17
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Multiplexers... for the patient and somewhat tech-capable, if a laptop/PC is part of your system, look into the Keyspan 4-port serial/USB converter. It handles all of the mux/de-mux tasks, allows multiple rates (e.g., some ports at 4800, some at 38400), and provides serial connectors (DB-9), now seldom seen on laptops. I use one to handle GPS, autopilot, SeaTalk (in and out), AIS, radar in and out (nav data in, target data out), VHF in and out (nav data in, DSC data out), and EPIRB (nav data in). Wiring it to cope with device failures (e.g., GPS takes a hike) took a little thinking but, overall, this is a surprisingly simple, tidy solution.
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Old 09-12-2008, 09:55   #18
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Originally Posted by SelkirkWind View Post
In order to do this, you have to have an E85001 installed I thought. Without an NMEA direct interface, Scotte is simply doing sneaker net. Good idea for a charter boat actually!
Sorry to disagree but it's not necessary providing that the NMEA port is not used for other input/output devices. In fact the Route upload/download I suggest will only work through the C/E series NMEA port. This port can be configured as standard 4800 baud or as 38400 baud for AIS input & still output NMEA (including route transfer) albeit at the higher speed.

The Seatalk/NMEA interface is useful otherwise though providing extra connectivity when needed. In my case I historically have a B & G instrument system and need NMEA connectivity. As my C80's NMEA port is used for AIS, I added an E85001 to allow instrument data to be fed to the C80 and autopilot data from it to be sent to my B & G autopilot. See attached diagram. Note that a manual switch is used to select Route upload when needed instead of AIS data. The multiplexer is relatively simple Noland 4800 baud. Note also that howl round, which I admit looks a possibility, is blocked by the B & G NAV instrument. It's all been working fine for a few years now.

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Old 09-12-2008, 10:02   #19
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Multiplexers... for the patient and somewhat tech-capable, if a laptop/PC is part of your system, look into the Keyspan 4-port serial/USB converter. It handles all of the mux/de-mux tasks, allows multiple rates (e.g., some ports at 4800, some at 38400), and provides serial connectors (DB-9), now seldom seen on laptops. I use one to handle GPS, autopilot, SeaTalk (in and out), AIS, radar in and out (nav data in, target data out), VHF in and out (nav data in, DSC data out), and EPIRB (nav data in). Wiring it to cope with device failures (e.g., GPS takes a hike) took a little thinking but, overall, this is a surprisingly simple, tidy solution.
I use the Keyspan Serial to USB dongle between my PC and my GPS. I like their quality. Plug it in and it works.
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Old 09-12-2008, 10:13   #20
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Sorry to disagree but it's not necessary providing that the NMEA port is not used for other input/output devices. In fact the Route upload/download I suggest will only work through the C/E series NMEA port. This port can be configured as standard 4800 baud or as 38400 baud for AIS input & still output NMEA (including route transfer) albeit at the higher speed.
I agree with you. In my system, the NMEA port is tied to the ST60s and the GPS. If it was not used I would not have needed the 85001. Sadly, coming back from the BVI last week, Delta lost my bag with all of my manuals in it. As soon as I get my system schematic, I will re-think the best way to do this in a Raymarine system.
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Old 09-12-2008, 10:41   #21
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Originally Posted by SelkirkWind View Post
I agree with you. In my system, the NMEA port is tied to the ST60s and the GPS. If it was not used I would not have needed the 85001. Sadly, coming back from the BVI last week, Delta lost my bag with all of my manuals in it. As soon as I get my system schematic, I will re-think the best way to do this in a Raymarine system.
Can you not connect the ST60 instruments to your MFD via Seatalk? If your GPS is a Raymarine one that should also allow Seatalk connection, freeing up the NMEA port.

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Old 09-12-2008, 10:52   #22
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Excellent question! I have two GPS devices. I have a Garmin attached to the PC and the Raymarine attached somehow to my E80. The reason for this is a little convoluted. I use Rosepoint Navs (Coastal Explorer, AKA formerly Maptech Navigator Pro). I have noted a significant chart position error on the Raymarine charts that does not exist on my RSPT charts. I have been trying to determine if it is just Raymarine's charts or the Raymarine GPS. I have not got to the bottom of this yet.
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Old 09-12-2008, 10:59   #23
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Can you not connect the ST60 instruments to your MFD via Seatalk? If your GPS is a Raymarine one that should also allow Seatalk connection, freeing up the NMEA port.

Regards
Your question sunk in. You are right, the Raymarine GPS and the ST60s and such are either Seatlak or Seatalk II as is the autopilot. Maybe that output is open. Now the question of how to get to it.........
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Old 09-12-2008, 11:13   #24
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Quote:
Originally Posted by SelkirkWind View Post
Excellent question! I have two GPS devices. I have a Garmin attached to the PC and the Raymarine attached somehow to my E80. The reason for this is a little convoluted. I use Rosepoint Navs (Coastal Explorer, AKA formerly Maptech Navigator Pro). I have noted a significant chart position error on the Raymarine charts that does not exist on my RSPT charts. I have been trying to determine if it is just Raymarine's charts or the Raymarine GPS. I have not got to the bottom of this yet.
Almost certainly the discrepency is with the charts. This is sadly quite common especially with Navionics charts. Your GPS receivers will generally either give you an accurate position or nothing at all. To prove this you could program your E80 to repeat it's Raymarine GPS signal via the NMEA port and on to your PC. I am sure you will see exactly the same position.
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Old 09-12-2008, 13:04   #25
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I agree with you. In my system, the NMEA port is tied to the ST60s and the GPS. If it was not used I would not have needed the 85001. Sadly, coming back from the BVI last week, Delta lost my bag with all of my manuals in it. As soon as I get my system schematic, I will re-think the best way to do this in a Raymarine system.
+1 - no need for even the GPS data to go to the ST60's via NMEA. Assuming you have a Ray[something] a/p with, in particular, a Ray[whatever] course computer, it'll take the NMEA stream from the laptop and pass along position data and waypoint data to the rest of the ST60's via SeaTalk (at least that's how I wired OWTW).

Manuals... head off to Raymarine Marine Electronics - Welcome and grab all of the manuals in PDF format.
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Old 09-12-2008, 13:15   #26
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Excellent question! I have two GPS devices. I have a Garmin attached to the PC and the Raymarine attached somehow to my E80. The reason for this is a little convoluted. I use Rosepoint Navs (Coastal Explorer, AKA formerly Maptech Navigator Pro). I have noted a significant chart position error on the Raymarine charts that does not exist on my RSPT charts. I have been trying to determine if it is just Raymarine's charts or the Raymarine GPS. I have not got to the bottom of this yet.
Two GPS' active at the same time? Please say you only use one at a time. Anything else is going to lead to positional schizophrenia and that leads to the digital laughing academy. Don't go there.

A friend with old Autohelm (pre-Raytheon) gear that included a GPS receiver and a Micrologic GPS ('member them?) used to periodically sail off to Spain or Hawaii and back in the span of a few seconds as the GPS' fought about who was in charge of providing fixes.

Even on OWTW, I periodically have a problem with the Type 300 course computer trying to send positional data, via SeaTalk, to the NMEA converter. Coastal Explorer loses track of the real GPS (only heard on a dedicated port on the laptop) for a second and grabs onto the data from the Type 300. Except the Type 300 can't originate fixes so it repeates the same fix over and over and over and... anyway, I've banged heads with Rose Point over this issue.

The current beta release is supposed to address the problem the right way (refuse fixes from specified ports, unlike the work-around of telling CE to ignore GLL, etc. on specific ports). I haven't tested it and won't be likely to until next spring, alas.

Bottom line:, two active GPS' in a common data structure? Bad, bad, bad!!!
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Old 09-12-2008, 13:33   #27
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Excellent question! I have two GPS devices. I have a Garmin attached to the PC and the Raymarine attached somehow to my E80. The reason for this is a little convoluted. I use Rosepoint Navs (Coastal Explorer, AKA formerly Maptech Navigator Pro). I have noted a significant chart position error on the Raymarine charts that does not exist on my RSPT charts. I have been trying to determine if it is just Raymarine's charts or the Raymarine GPS. I have not got to the bottom of this yet.
Coastal Explorer is not Maptech Navigator Pro and vice versa. Maptech Navigator Pro is a variant of Coastal Explorer (more like cousins with common ancestors) but they are not the same product. Yes, Rose Point Nav wrote and maintains both of them.

As to the Raymarine plotted data not matching what's seen with CE, the big question is what are you using for charts with CE? If you're talking about navigating where NOAA ENC and RNC (i.e., "vector" and "raster") charts are current (CONUS, Alaska, Hawaii, Puerto Rico, USVI) and there's a discrepency, I'd bet on the CE display, too.

However, if you're not in the NOAA chart set (e.g., BVI or basically anywhere but PR and USVI), I'd be a little less certain that CE's showing you the right picture. For example, Imray-Iolaire charts of the Caribbean can be spot on in some cases, until you're zoomed into (roughly) harbor scale, at which point the wheels fall off. The problem is that some of the I-I charts lack needed scaling data or at least it's not right. As a result CE (and Raynav and Nobeltec) get the aspect ratio wrong (quick check: look at the compass roses on the charts - if they're round, all is well, if they look more like footballs, not so good). Sailing between Grenada and St Vincent we found our plotted position was as much as a 1/4 nm off - putting us on the hard while we were floating at anchor.

That said, NOAA charts are, of course, updated on a regular basis while chip charts are "what was burned in is what you get". Major land masses aren't likely to change (well, there is California to think about...) but I'd expect details (mostly aids to navigation and marina details) to differ. However, if you're seeing wholesale land mass errors (e.g. Marsh Habor, Abacos is moved 5 nm east from its true position), I'd look at the GPS data driving the display (see note re: two active GPS receivers).
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Old 09-12-2008, 20:44   #28
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If there is only one NMEA device going into the C-70 (typically, a laptop or an AIS receiver), a mux (multiplexer - combines data neatly) isn't needed. However, if you want a laptop and an AIS receiver, it's mux time for two reasons: 1) two talkers [laptop, AIS], 2) devices operating at different rates (Raymarine accepts NMEA at 4800 baud only, with the exception of AIS, at 38,400 baud). It's not good form to tie multiple listeners (laptop, EPIRB, etc.) to a single NMEA output port but it usually works.
When you say "Raymarine accepts NMEA at 4800 baud only, with the exception of AIS, at 38,400 baud" this isn't correct, if you are talking about the C/E-Series. While NMEA 0183 is technically 4800bps, the C/E-Series will accept NMEA sentences (all NMEA sentences) when set to the "AIS" mode at 38400bps, however you'll need something to do speed conversion to do this, if you have anything requiring 4800bps NMEA in the loop (like the Brookhouse MUX I have, there are others as well).

As far as multiple listeners to a single talker, it is not correct that you can only have 1 listener. The NMEA 0183 spec is clear that you can multiple listeners, however it is not specific on the exact number, and the reality is it depends on the UARTs/drivers/optoisolators used. A number of listeners around 4 should be a good ballpark. Note, however, that a computer's UART is RS-232, not RS-422, and therefore not precisely NMEA.
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Old 09-12-2008, 20:52   #29
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Bottom line:, two active GPS' in a common data structure? Bad, bad, bad!!!
Absolutely! I've got two Garmin GPS's in my setup. While my MUX can do GPS failover (where only 1 GPS is active at a time - specifying a primary and backup in the config), I've wired this in manually via a simple switch at my nav station to free up a port on the MUX.
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Old 09-12-2008, 22:05   #30
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When you say "Raymarine accepts NMEA at 4800 baud only, with the exception of AIS, at 38,400 baud" this isn't correct, if you are talking about the C/E-Series. While NMEA 0183 is technically 4800bps, the C/E-Series will accept NMEA sentences (all NMEA sentences) when set to the "AIS" mode at 38400bps, however you'll need something to do speed conversion to do this, if you have anything requiring 4800bps NMEA in the loop (like the Brookhouse MUX I have, there are others as well).
The NMEA 0183 spec limits things to 4800, or at least when I thrashed with Raymarine support about this, they were very insistent on the point, citing NMEA standards as the reason why they used 4800 only. Unfortunately, it's not too hard to swamp a 4800 baud link (toss in a lot of GPS receiver status and some other long sentences along with lots of short sentences, and it's possible to saturate the link). In fact, that's why I asked about moving to at least 9600.

It sounds as though the C and E series finally smelled the bacon on the point.

Quote:
As far as multiple listeners to a single talker, it is not correct that you can only have 1 listener. The NMEA 0183 spec is clear that you can multiple listeners, however it is not specific on the exact number, and the reality is it depends on the UARTs/drivers/optoisolators used. A number of listeners around 4 should be a good ballpark. Note, however, that a computer's UART is RS-232, not RS-422, and therefore not precisely NMEA.
Re-read what I said - "it's not good form", not "it can't be done" or "it shouldn't be done". The risk is one or more listeners may have various electrical problems which the combined output can either exacerbate or reveal in the first place. Ground loops come to mind quickly. Additionally, some receiver/listener may, because of poor design or poor wiring, present a great load than another. It's something of a gamble whether or not any given combination will work. All of that said, I certainly send data from any one of my three NMEA out ports to multiple destinations. So far, nothing has let the magic smoke out of the black boxes.

And a big thumbs up for switch selectors for GPS sources. OWTW is wired to choose one of two receivers (one is in the cockpit, one's below), as well as choosing whether to send the GPS data directly to the autopilot or off to the laptop (both receivers carry the same routes in use on the laptop - allowing for three potential sources for routing). All of this has been tried in "live fire exercises" and, much to my surprise, it all worked as expected. I assume, therefore, a meteor will land on the boat any day now...
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