GPS Interfacing

[tonyappuk]

Hallo All

I have been lurking for some time and as a result have installed opencpn and found some cm93 charts. In winXP I have persuaded the charts to open eventually after the usual probs with unfamiliar software but no way can I persuade my GPS to talk to opencpn.

The GPS is a USB puck type which works fine with Seaclear but I suspect that the com port speed of the puck of 38k is not recognised by opencpn. I gather that this should happen automatically which is good because to alter the puck port speed is not possible with the software provided with it.

Is there an entry I could add to opencpn.ini to force it to see 38k or will I have to used my limited ability and use opencpn in Linux? Or does anyone have some suggestions I could try?

Thanks for your anticipated help!
Tony

[cagney]

Have you tried these instructions Setting Up GPS | Official OpenCPN Homepage ?

Thomas

[tonyappuk]

Thomas

I thought I had already tried everything but I have gone through that help page twice again, each time setting the port speed in the Prolific driver properties to 4800 and each time my Mini-CDU prog supplied with the puck will only connect at 38k (Strangely the driver properties window still remains at 4800) Oh and of course opencpn fails to show anything in the NMEA data stream window. I'm not clear if the driver properties speed setting has an external effect into the puck or not but it doesn't seem to want to work. The opencpn help files say that the port speed, baud rate, etc are set automatically. Does this happen in XP or should I try again in Linux?

Thanks for your prompt response.
Tony

[champ8242]

Tony,

It works with XP! No worries.

You can use Hyper terminal in XP to test if you get readable NMEA GPS data out of your serial port @4800.

Bart

[tonyappuk]

Bart

Thanks for your reassurances about opencpn working with XP, I will persist with my efforts. Unfortunately my problem is not with being able to see the NMEA data stream it is with being able to switch my hockey puck GPS away from its default 38400 baud to 4800. Since there is an assurance in the opencpn help files that the software will accommodate to any com port specs I had hoped that it would do just that but it seems not. The GPS is from Maplins in the UK and it appears to use the SiRF star III chipset which is used very commonly in modern GPSs but the control of baud rate needs NMEA words into the device which I have no means of generating. Hopefully that is what opencpn is designed to do but I'm not sure. It may just be that the design tries to recognise the data stream fed to it and adjusts itself to suit. That is what I assumed and still hope but I think I will need one of opencpn's programmers to confirm or deny this.
Thanks for responding
Tony

[idpnd]

My USB GPS had a management software/driver (BU 353) to set the baud rate etc.?

[donradcliffe]

If you can get your puck to work with Seaclear at 38k, then try setting the GPS port in Opencpn to AIS port (shared), and set the AIS port to your puck's com port--the AIS data stream runs at 38k, and Opencpn may pick up the gps data even though there are no AIS sentences.

[tonyappuk]

idpnd
Unfortunately it seems my particular GPS needs baud rate of 38400 as default and nowhere can I find software to give me the facility to control via NMEA sentences.

donradcliffe
You're a star!! It works and I'm plotting on my CM93 map set. Thank you so much. I think it would be worth suggesting that the software in Windows at any rate does not automatically adjust to incoming NMEA baud rate etc. Is there anywhere I should post this for attention. Even if your work around is the answer it would be nice to have it pointed out. Thanks again.
Tony

[martinbradford]

The new version of mini-CDU (downloadable from the manufacturers web site) allows you to change the baud rate of the GPS - I had the same problem with a ND-100 GPS from the same manufacturer. See How to change baud rate on ND-100 (Mini CDU v1.03/Baud Rate Tool) - hopefully it will work with your GPS too.

[tonyappuk]

martinbradford
As you will have read I have managed to make it all work using donradcliffe's suggestion of using the AIS input but I thank you for this link and will download the new mini-CDU program. It will obviously make the GPS puck more useful if the baud rate can be changed from the default but opencpn, at least, seems to work fine through the AIS port at 38400. That may need rethinking if I ever try to input AIS as well as GPS but that would need some sort of port management software anyway I think. Thank you.
Tony

[tscher]

Hi all,

I just wanted to thank you for the information above! I have a Navilock NL-454US stick, which fresh-from-the-factory also sends its data with 38400 baud, and would not work in OpenCPN. By following Martin´s link and downloading the latest MiniCDU Version, I was able to set the baud rate to 4800. Now its all running nicely. (Maybe this tool works for all Sticks using the MStar MB2122 chipset ?)

One more thing: sometimes, when booting up with the GPS connected, Windows will see the GPS data on the serial port and wrongly decide there is a serial Mouse connected. which results in a) the mouse pointer jumping around randomly, and b) the GPS´s COM port being blocked. To prevent this, one must disable the Plug-n-Play functionality of the COM Port. There is a handy tool called "Com Port Plug and Play Blocker" by a company called "Stentec" available for free here.

best regards,
tscher

[rdempsey]

Originally Posted by tscher

One more thing: sometimes, when booting up with the GPS connected, Windows will see the GPS data on the serial port and wrongly decide there is a serial Mouse connected. which results in a) the mouse pointer jumping around randomly, and b) the GPS´s COM port being blocked. To prevent this, one must disable the Plug-n-Play functionality of the COM Port. There is a handy tool called "Com Port Plug and Play Blocker" by a company called "Stentec" available for free here.

This also works and doesn't require new software:

-Boot the computer with the GPS receiver attached. The cursor will be
jumping around and all sorts of unwanted stuff will be happening. Disconnect the GPS. The computer will settle down.
-Select Control Panel - System - Hardware - Device Manager.
-Click on the "+" next to Mice and other pointing devices.
-Click on "Microsoft Serial Ball Point" - This is what Windows
2000/XP thinks that your GPS receiver is. Select "Actions" and then "disable".
-Click "OK" to close each window
-Reboot the computer with the GPS attached. All should be well.

[DotDun]

OpenCPN works with the com port at 38400 for the GPS. I'm wondering if when it fails, what the GPS puck com port is set to in Device Manager. I'm assuming that OpenCPN gets the speed setting from DM, hence if DM doesn't match the GPS puck settings, OpenCPN is messed up where as SeaClear probably tries various speeds.

[champ8242]

Originally Posted by DotDun

OpenCPN works with the com port at 38400 for the GPS....

Don't think so! it's either 4800 or 38400. It's NMEA 0183 low or high speed like AIS. But most (if not all) of the multiplexers work on high output.

Bart

[DotDun]

Originally Posted by champ8242

Don't think so! it's either 4800 or 38400. It's NMEA 0183 low or high speed like AIS. But most (if not all) of the multiplexers work on high output.

Bart

I believe we have a mis-understanding. I stated that OpenCPN works with a GPS running 38400 and you tell me "Don't think so! it's either 4800 or 38400."

Here I sit with OpenCPN 1.3.6 on WinXP using an Actisense NGW-1 ISO set to run 38400 (Actisense assisted changing it from 4800 to 38400) on the 0183 side into a USB/Serial adapter that is set for 38400 in Device Manager and it works. The same 0183 feed is connected to Furuno NavNet3D set to 38400 and picking up the wind data from Raymarine transducer pod coming across the NGW-1.

Airmar G2183 --> NGW-1 @ 38400 --> USB/Serial --> OpenCPN 1.3.6

Conclusion: OpenCPN works with a GPS connected at 38400!