Interfacing NMEA Data to Computer

[jboats]

Originally Posted by Paul Elliott

The HX851 has an unbalanced output (NMEA+ / ground), and should interface well to a low-cost RS232/USB adaptor. Just make sure you have the proper drivers for the adaptor and your computer's OS.

Connect the Blue wire (the radio's NMEA Out+) to the RS232 pin 3, and the Green wire (radio Ground) to RS232 pin 5. (Assuming the RS232 adaptor has a DB-9 connector, which most do)

Nice, sounds like its worth the try on the cheaper adapter. I'll refer to your spec's. Now I just need an old serial cable to cannibalize for the 851 out connector, swap meet here I come.

J

[Wireless1]

Sorry to get in on this thread late, but I successfully did the very thing you want to do years ago with my Raymarine ST-50 instruments. (minus the RADAR stuff you want to do) I wanted duplicate ST-50 instruments at my nav station but thought it cost prohibitive and also a waste of space. So I wrote a computer program in Visual Basic under (don't laugh) Windows 95. I created exact "look alike" copies of the ST-50s using the tools available in Visual Basic (ver. 4) and even had my virtual wind instrument with a needle pointer! ( for me that was the most tricky code in the whole project). It worked really well. The rest of the displays were all digital except for wind point. Wind speed was a digital box in the wind point instrument just like the real ST-50 wind instrument. The thing that was really cool was that the virtual instruments were scalable. Each instrument was in it's own sizable window and they could be moved all over the desktop, docked together, or even minimized if not needed (but still active). Also, if I wanted to see just one HUGE instrument from across the cabin I could maximize it's window, or drag it's edge corner, and fill the entire laptop screen! Ha! Usually I had that set as a REALLY HUGE knotmeter display!! Anyway, I don't recall it being too difficult from a programming standpoint. I do remember that parsing out the NMEA data strings was kind of a pain. AS I recall the NMEA 0183 was all comma delimited data where you got the "HEADER" for the sentence and then the data followed, and most of my bugs were in my text parsing routines but I did get it working flawlessly. (did I mention the NMEA was all text strings?)

I don't even know if Visual Basic is alive any longer. When I quit programming with it they were shifting over to something called VBNet... That's when I got out of it. I don't' think my app would even run now under Windows XP, Vista, or Win 7 because you needed to install the VBRunxxxx.dll "runtime" file for the system to interpret VB code to the Win OS and that may not be supported nowadays. Still...it was great fun to do. If anyone knows if this old code would work now, or could be ported over let me know, and I'll try to find it on some old laptops out in the garage! BTW, I did not use any kind of interface box. The ST-7000 AP had NMEA out and I just went into the serial port of my laptop using a DB-9 connector with no problem.
Cheers!

[Wireless1]

Holy cow.... I just did a search on Visual Basic and it is STILL alive and well!!
I'm going to rummage around and see if I can find my ST-50 app. That is too funny. I thought VB would have died out long ago.
Fingers crossed I can find it.

[hellosailor]

Wireless-
Support Statement for Visual Basic 6.0 on Windows Vista and Windows Server 2008
MS claims VB6 will run flawlessly under the new OSes, so it sounds like your "virtual instruments" would work very nicely!

jboats-
The no-tech effective difference between RS422 and RS232 is that 422 is a "differential" bus, using three lines (+, center ground, and -) instead of just two (+ and - which is set at ground) capable of higher speeds and longer distances. In many ways the two are essentially the same.
Those cables aren't really just cables, the "chip" is a lowly computer that is actively converting signals from one bus to the other. That company makes good products, but why complicate life with RS422 unless you are using a Mac that is built for it?
Stick to an RS232 to USB converter, one that has the "Made for Windows xx" logo on it, so you know it has been certififed and tested to work with your version of Windows. The logo may add $5 to the price tag but it also tells you the product has had extensive testing and usually works. Not always, but damn near so.

[jboats]

COol, thanks. I rigged up a connection from the HX851 NEMA out to my PC using a RS232 to USB adapter. I cut off the end of a spare DB9 male and used clips to test the wire connections until I found the correct color for the + and - I finally got clear sentences with just the right amount of jiggling for a minute but couldn't maintain ungarbled data when connecting with my chart software. Without a solder kit to make good connections I'm going to just get a USB GPS, although the solder kit would be cool to have...

[jboats]

Originally Posted by Wireless1

Holy cow.... I just did a search on Visual Basic and it is STILL alive and well!!
I'm going to rummage around and see if I can find my ST-50 app. That is too funny. I thought VB would have died out long ago.
Fingers crossed I can find it.

NiCE. if you get that ported to 7, let us know! Also post a pic of your DB9 connection to your PC.

Thanks,
J

[hellosailor]

j, a basic $5 soldering iron (plugs into AC) and the solder included with it will be good enough to solder up your cable reliably. With small wires like that, it won't be critical work so there's no fear of failure. OTOH, those little AC soldering irons ALWAYS find a way to twist around and burn you if you give them a chance to, so make sure it is "secured" when you put it down to heat up.

It will do quite a variety of work and small repairs. For a step up, about $20-25 should buy you a Weller ("the" brand name) soldering gun with a trigger on it, more control, better heat, either one is a lifetime tool but the $5 one is of course easier to stow on a boat.

[SV Demeter]

My boat has a seatalk to NMEA converter and also a serial port connector coming out of that box. Came wired in the boat but I have never tried plugging it into my laptop. Im going to buy one these serial to USB converter thingies you guys are talking about and give it a try. My question, and maybe this is an OpenCPN question, is what should I expect to see in Open CPN? Is there a tab or window or something that will display the readings from my depth sounder, knot meter, and wind instrument? Assuming of course that the whole kit actually works and is able to outout NMEA sentences to the laptop.

Perhaps a second question too. I have recently installed a Class B AIS transponder. The one I installed has both a high speed NMEA output and a Low Speed NMEA output, as well as a USB output. I connected the low speed output, 4800 Baud IIRC, to the Seatalk to NMEA converter on the NMEA IN side. It is my hope that the GPS antenna supplied with the AIS transponder will be able to get GPS data to my Raymarine instruments via the Seatalk to NMEA converter using this low speed connection?

It would be very nice if I could get my instrument data, GPS info, and AIS info into Open CPN all through one USB cable but Im thinking for the AIS data I will need to connect to the laptop using the high speed, 34800 Baud, connection or use the USB output from the AIS reciever? Two USBs going to the laptop is not the end of the world but one would be better. I have a USB GPS thingie as well, i think you guys call it a dongle? Thats what I have been using prior to installing the AIS to get GPS info to Open CPN. Should I not be able to use the GPS info coming from the AIS transponder and save my dongle as a back up?

The plan is to keep the lapton secured inside the nav table and connect an external monitor and keyboard and mouse so the nav table itself is less cluttered and the laptop is in a safer location. This keyboard and mouse will likley require a USB port and IIRC my laptop only has 3.

Comments? Suggestions? Pitfalls to watch out for? Please be patient with any responses and gear them to the tech level of a complete idiot if possible.

[hellosailor]

Demeter, the only way a human being can survive the attack of silicon life forms is to divide and conquer. Split 'em up, divide the problems, conquer one and only one at any given time.

Open Cptn: No idea.

Class B AIS transponder...w/ high speed NMEA output
and a Low Speed NMEA output,
as well as a USB output.

I would expect they are all NMEA and none can make a Seatalk device happy.
You need a Seatalk converter box of some kind that has "NMEA IN" and "Seatalk Out" if you want that conversion, AFAIK.

"the GPS antenna supplied with the AIS transponder will be able to get GPS data to my Raymarine instruments via the Seatalk to NMEA converter using this low speed connection?"
Again, probably not. The GPS antenna, if it is just an antenna, needs to connect only to the rest of the GPS it is designed for. Which means the only GPS output would be from the AIS, in NMEA format not Seatalk. And if the GPS is a complete "puck" style GPS, not just an antenna, again it will probably only output NMEA, not Seatalk. "NMEA IN, SEATALK OUT" converter again required if you want Seatalk out of it.

?It would be very nice if ...info into Open CPN all through one USB cable" You can join USB slave devices with a powered or unpowered USB "hub" that will take up to 5 ports, and then the hub connects to your USB master device (the computer) with one cable. There are limits of USB cable lengths, typically 15' (I may be wrong on that, I never push it) for any cable run unless you use a powered hub or USB repeater.

"I have a USB GPS thingie as well, i think you guys call it a dongle?"
Well, a dongle is any dumb gizmo, often a security code key, that is "dongling" out of the computer on a wire. I'd call a USB GPS a USB GPS, even if it looks a lot like a dongle. Yaknow, like that blue rope over there by the big stick on your boat? Using the right name sometimes helps.<G>

"Should I not be able to use the GPS info coming from the AIS transponder and save my dongle as a back up?" Absolutely. One GPS should be enough, and the one on the AIS box would be the prefered one. I'd put #2 in a small waterproof container with some dessicant (tupperware, jelly jar, metal tin sealed with electrical tape) and put it aside as a spare. Remember that there's usually a back-up battery in there and any GPS will take longer to wake up after it has been sleeping a long time, so when you DO grab it again--give it a chance to wake up.

"This keyboard and mouse will likley require a USB port and IIRC my laptop only has 3."

Again, a USB hub solves that problem. Although you might want to look at a Bluetooth (requires less power) or WiFi mouse and keyboard. If your laptop has Bluetooth built in, they can work on that without requiring any cords or plugs.

Divide and conquer, one at a time. Then troubleshoot each one, one at a time, to make sure they're really working before you move on to the next one.

[SV Demeter]

Thanks Hello you are right, lots of issues here I will try numbering:

1. I will post over in the Open CPN thread about instrument data in Open CPN, again assuming my converter will translate Seatalk data to NMEA.

2. You mentioned:
"I would expect they are all NMEA and none can make a Seatalk device happy.
You need a Seatalk converter box of some kind that has "NMEA IN" and "Seatalk Out" if you want that conversion, AFAIK."

I already have a Seatalk to NMEA converter. This guy:
Raymarine Marine Electronics - PC-SeaTalk-NMEA Interface Box

My assumption is that it works both ways. It has NMEA IN and NMEA Out as well as Seatalk connections so I was assuming it could translate NMEA to Seatalk as well as being able to translate Seatalk to NMEA.

3. The GPS antenna connects to the AIS transponder and is this AIS unit:

em-trak - em-trak B100

From what I read I was thinking it would be able to provide GPS data to the instruments provided I could convert that data from NMEA to Seatalk (see #2 above) Thats why I connected the low speed output from the AIS unit to the NMEA IN ports on the seatalk converter.

4.On the keyboard and mouse, if I understand your suggestion is to look for a blue tooth keyboard and mouse and thereby eliminate the need for USB cables? I like that as I would then not need the sensor on the nav table. Will look further.

Thanks again.

[DotDun]

Originally Posted by SV Demeter

Perhaps a second question too. I have recently installed a Class B AIS transponder. The one I installed has both a high speed NMEA output and a Low Speed NMEA output, as well as a USB output. I connected the low speed output, 4800 Baud IIRC, to the Seatalk to NMEA converter on the NMEA IN side. It is my hope that the GPS antenna supplied with the AIS transponder will be able to get GPS data to my Raymarine instruments via the Seatalk to NMEA converter using this low speed connection?

It would be very nice if I could get my instrument data, GPS info, and AIS info into Open CPN all through one USB cable but Im thinking for the AIS data I will need to connect to the laptop using the high speed, 34800 Baud, connection or use the USB output from the AIS reciever? Two USBs going to the laptop is not the end of the world but one would be better. I have a USB GPS thingie as well, i think you guys call it a dongle? Thats what I have been using prior to installing the AIS to get GPS info to Open CPN. Should I not be able to use the GPS info coming from the AIS transponder and save my dongle as a back up?

Per the manual on your AIS transceiver, it will multiplex NMEA data between it's two 0183 ports, hence you should be able to feed instrument data from the Seatalk - NMEA box into the low speed port on the AIS and connect your laptop to the high speed port on the AIS and see all the data you're wanting (Seatalk instruments, GPS, AIS).

At least that's the theory from reading the manual... YMMV

[SV Demeter]

Originally Posted by DotDun

Per the manual on your AIS transceiver, it will multiplex NMEA data between it's two 0183 ports, hence you should be able to feed instrument data from the Seatalk - NMEA box into the low speed port on the AIS and connect your laptop to the high speed port on the AIS and see all the data you're wanting (Seatalk instruments, GPS, AIS).

At least that's the theory from reading the manual... YMMV

Ok that makes sense but Im thinking this method would not allow me to get GPS data TO the instruments FROM the AIS transponder. Isnt this a multiple talker issue? The talkers being the AIS transponder and the instruments?

[jboats]

So the end game here is to create a network between AIS > PC Chartplotter > Boat Chartplotter > Autopilot, correct? So that you could plot your routes on your PC with OpenCPN and then transmit that data to your Boats Chartplotter and Autopilot. This is what I'd like to do anyway. Drive the boat from below.

I'd think that any of the NMEA data would be available as long as the instruments were set up to receive it from your Seatalk bridge, or whatever DotDun said ^. The trick I think is to get the routes from OpenCPN back to the boat chartplotter and autopilot. My version of OpenCPN isn't working right now but I recall it having the ability to save out NMEA data, so it should be able to give you a file that can be sent to your boat chartplotter via something like HyperTerminal. So if that works a route shows up on your boat chartplotter ready to go. Then how do you get your AutoPilot to engage the new route? I bet if you can write/find the correct Seatalk sentences/code for your Autopilot you could create a text file and send it through Hyperterminal to the Autopilot via the Seatalk interface.

If there's not already an easier way, wait a few years and there will be an app for that. Wireless1 was talking about some software he wrote that mirrored the RayChart display to the PC, he would proly be the guy that could write the app. Too bad there's not a universal wireless solution to do this but I guess there's so many devices to support it would be difficult. It would be great to not have to run wires around a boat anymore. sigh

[SV Demeter]

[QUOTE=jboats;899124]So the end game here is to create a network between AIS > PC Chartplotter > Boat Chartplotter > Autopilot, correct? So that you could plot your routes on your PC with OpenCPN and then transmit that data to your Boats Chartplotter and Autopilot. This is what I'd like to do anyway. Drive the boat from below.

I'd think that any of the NMEA data would be available as long as the instruments were set up to receive it from your Seatalk bridge, or whatever DotDun said ^. The trick I think is to get the routes from OpenCPN back to the boat chartplotter and autopilot. My version of OpenCPN isn't working right now but I recall it having the ability to save out NMEA data, so it should be able to give you a file that can be sent to your boat chartplotter via something like HyperTerminal. So if that works a route shows up on your boat chartplotter ready to go. Then how do you get your AutoPilot to engage the new route? I bet if you can write/find the correct Seatalk sentences/code for your Autopilot you could create a text file and send it through Hyperterminal to the Autopilot via the Seatalk interface. "






Im not so concerned with being able to send routes from the laptop below to the chartplotter in the cockpit(dont have one of those) or the Autopilot. Im hoping to get the $$ to install a windvane for steering in the next year or two so I dont have use my power hungry loud autopilot offshore. I really just want to network my instruments, AIS, and PC so I can share data. It would be nice to see GPS info on my instruments in the cockpit like XTE, SOG, etc. and it would be nice to see instrument data like actual depth, speed, wind etc on the PC although thats less of a big deal to me as I have a repeater below at the nav table that I can use to see instrument data. I think what I have wired up should work but I need to get my masts back up to finish connecting everything and start testing.

[DotDun]

Originally Posted by SV Demeter

Ok that makes sense but Im thinking this method would not allow me to get GPS data TO the instruments FROM the AIS transponder. Isnt this a multiple talker issue? The talkers being the AIS transponder and the instruments?

OK, the B-100 AIS you have has (2) NMEA 0183 ports, (1) NMEA 2000 port, and (1) USB port (which is a HS NMEA 0183 port). But let's just talk about the (2) NMEA 0183 ports. One of them is 4800 baud and the other is 38400. Each one has a tx and rx. You stated the 4800 tx was connected to the 'NMEA in' of the ST-NMEA box (providing GPS data to the RM gear). Connect the 4800 rx to the 'NMEA out' of the ST-NMEA box. Per the manual on the B-100, it will multiplex each 0183 rx to the other 0183 tx, this takes care of the multiple talker problem. So the instrument data coming from the ST-NMEA into the B-100 on the 4800 port will be multiplexed with the GPS and AIS data on the 38400 tx port. Connect that one to your laptop via a USB serial adapter @ 38400.

The manual doesn't mention whether that multiplexing feature works on the USB port or not, but it might be worth a try, it may save you the cost of a USB serial adapter. BTW, be sure to configure (with proAIS) the B-100 to send full GPS data out, I think it defaults to something less than normal GPS output.

From page 19 of the B-100 manual:

The ports have bidirectional multiplexing, which means any messages which are received via the high speed are automatically transmitted via the low speed port and vice-versa. This is particularly useful when using a chart plotter having only a single NMEA0183 port as any other sensor such as a gyro-compass can be connected to the AIS transceiver via the low speed port and the AIS transceiver can be connected via the high speed port to the chart plotter resulting in the chart plotter receiving both AIS information and heading information simultaneously.