NMEA to USB

[brak]

Incidentally, from my experience Prolific chipset-based USB-serial adapters (at least the ones based on PL-2303 chip) tend run the gamut from marginal to very poor. This is, likely, at least in part due to myriad of manufacturers using them and building products of not so great quality.

The last two USB-serial cables with PL2303 chipset turned out to only work for input, not output. When I called the reseller (who also seems to be the OEM, I think) the answer was "what do you expect from cheap devices" (so now I am not buying from these guys anymore, but the issue still remains).

[ChuckSK]

Actisense also makes a nmea 0183 to USB adapter (USG-1). I have had good luck with this adapter connecting opencpn to a Raymarine autopilot.

Chuck

[sded]

You might also check out the Edgeports, which are widely used and regularly available on eBay as well. I use a 4 port version and it has been very reliable. Tested it against Windows 7x64 and it found and installed drivers; I have been using it for some time with Vista and XP.

[Charlesc]

Originally Posted by unbusted67

Thats cool. I just realized though that we have a 15 Pin Dsub connector on the laptop and that we won't be needing to use the USB ports after all. What would be the proper pin out for that?

on most serial DB-9 connections use pin 2 " siganl" and pin 5 #ground".

[Captain Bill]

The 15 pin port is your Video output port, it is not a serial port. Hooking this thing up to an NMEA port will probably damage your computer. There are USB GPSs out there for less than $40. I use a Garmin 18x which is available for about $70. It looks like most quality USB-Serial connectors will run you $100 or a bit more. Why not go with the separate GPS for the laptop. The bluetooth GPSs are nice but you have to power them separately. With the USB ones you get the power from the USB port which simplifies the matter. It's also nice to have a backup in case your primary goes down.

[unbusted67]

Yup I actually just went out and grabbed a bluetooth GPS for $30 and linked it to one of the COM Ports. I am not super worried about powering it because we won't be using it as a primary. Thanks for the help guys. Now I know where my video input is!

[Kris L]

Just so everyone knows. NMEA-0183 is RS422 not RS232. The best solution to connect NMEA-0183 to USB is a "USB Optically Isolated Serial Port NMEA-0183 Opto-coupled Input, RS422 Output". You can find one on this web site. Consolidated Technologies Ltd.. You can probably find them other places too.

Kris L

[AnchorageGuy]

This might be very helpful for someone
http://www.syz.com/gps/gpsinfo.pdf
WG

[cal40john]

Originally Posted by Kris L

Just so everyone knows. NMEA-0183 is RS422 not RS232. The best solution to connect NMEA-0183 to USB is a "USB Optically Isolated Serial Port NMEA-0183 Opto-coupled Input, RS422 Output". You can find one on this web site. Consolidated Technologies Ltd.. You can probably find them other places too.

Kris L

What's the point as far as Garmin is concerned. RS-422s big advantage is differentially driven pairs. Garmin has a single ground wire which is also used for power as well as data ground. Might as well use RS-232 at that point.

John

[Kris L]

Originally Posted by cal40john

What's the point as far as Garmin is concerned. RS-422s big advantage is differentially driven pairs. Garmin has a single ground wire which is also used for power as well as data ground. Might as well use RS-232 at that point.

John

John,

There is a really good answer to that. Here is a really good post answering your question. http://www.cruisersforum.com/forums/...2-a-12967.html. NMEA-0183 is RS422 not RS232.

Kris L

[cal40john]

Originally Posted by Kris L

John,

There is a really good answer to that. Here is a really good post answering your question. http://www.cruisersforum.com/forums/...2-a-12967.html. NMEA-0183 is RS422 not RS232.

Kris L

Yes that thread says exactly what I'm saying. Garmin is not following NMEA convention. To have differential transmission you need a pair of data signal wires for each of the transmit and receive, 4 wires total. A signal + and a signal - for each. Garmin does not even have a separate data ground from its power ground. And a data ground is not the same as a signal - for each of the transmit and receive.

John

John

[goboatingnow]

Garmin doesnt follow RS422 conventions, its effectively a 5V RS232 signal. But most PC serial ports ( and serial to usbs) will handle rs232 ie Garmin down to below 5V so it is possible to connect Nmea0183 dirrectly to a PC serial port.

[Kris L]

True, Garmin does not comply to the NMEA 0183 spec regarding differential pairs but connecting directly to the computer RS232 port also breaks the NMEA 0183 requirement for opto-isolation between Talker and Listener. The opto-isolation requirement was created to prevent ground loops within an NMEA 0183 system.

Kris L

[Charlesc]

Originally Posted by unbusted67

John thanks for your response. I just reread my previous post and realized it was a little too jargonny. Let me rephrase:

How do people generally connect Open CPN to GPS?

It looks like we have Dsub input on our computer will that work? If so what is the pin configuration?

After you get the USB to serial adapter, you will need to connect your NEMA TX or output from GPS to PIN 2 on cennector and Ground to pin 5.

Tell your software to look for the gps " if it has that ability" or check to see which com port the adapter is .

Soome of the less expensive/free software is limited to which port it will use .

Also check that the baud rate is the same on that port or you will have issues. If you get it going but mouse go crazy, you have a conflict in IRQ and port settings.


HAve done this many times and it can be done.


FAir Winds

Chuck

[hellosailor]

USB-to-serial adapters are not all created equally. If you buy one that is not Windows Logo Certified for your particular OS version, you may save $5. But those that are logo certified and listed on the Microsoft Hardware Qualification List (HCL) for the OS have been extensively tested and are known to work most if not all of the time.

IBM and Keyspan are two of the brands that are no more expensive than any others, logo certified models since USB first shipped.

Or, you can skip the logo certification, and if you're lucky the five bucks you saved will come back to bite you. Even if it works now--it may not work with the next device, or next program.