Opencpn

[Mistral]

Hi,have new laptop Lenova985 have installed CPN with all the CMap's,would now like to connect to GPS 72 which is at the moment connected to power on the boat and also to my DSC Radio to show my position all the time.Am sure that I can connect through the usb,but have not been sucsessfull. Would appreciate any help e-mail: mistral@bezeqint.net or Skype:mistralii Thanks in advance

[JeanneP]

Not knowing what GPS 72 is, the following may or may not help.

I have a mouse type USB GPS, which came with a disk providing the drivers.

This is the procedure I used for Windows 7. If you have a different operating system, try it anyway (Windows XP was pretty much the same)

Plug in the GPS. Go to Device Manager (Control Panel [click] System [click] Device Manager [click]

click on - Ports (COM and LPT)

You should see your GPS identified. If not, you might need to install the driver for it. Open that port to get information. You need to write down the COM number (i.e., COM1, COM9, whatever)

Then go to the Toolbox on CPN.

The first tab is Settings. Go down to "NMEA Options" then insert the port (i.e., "COM#") into "NMEA Data Source"

That should do it. You should now be able to see the GPS position icon on the appropriate chart.

Hope this helps.

J

[SailingPanacea]

Hi, OpenCPN is great, the garmin72 data stream should work well.

We have a "GPS bus". A terminal block that we share the data with a Furuno chartplotter,autopilot, AIS, DSC on the VHF, and position data to the PC.

The PC does not have a 9 pin serial port, we use a USB/Serial adapter (I/OGear) and a serial cable that has an end cut off, wires exposed and connected to the "GPS bus".

This is a gross description of of how we tackled our issues, if you need more info, let us know.

Rick

[Mistral]

Rick Hi,

Thanks for the info:Now for the more info. First do you have Skype if yes I am mistralii so maybe you can contact and then we can chat,that is I can ask question's. If not maybe on my e-mail as I get lost looking where to go on the forum. I am : mistral@bezeqint.net

My query is fairly simple. I have the garmin 72. It is attached to the power (cigerett lighter) has a fuse, plus 4 bare wires. The white one is not in use and the other three are connected to my DSC radio,which gives me my position on the radio. I have a cable with one side a usb plug which I can connect to the laptop,the other side has 4 bare wires white red green and black, I thought that I could solder two of the wires straight to the 2 wires that went to the DSC radio,if so how, and if not ,then what to do?

I hope all this makes sense.

Henry

[delatbabel]

Originally Posted by Mistral

My query is fairly simple. I have the garmin 72. It is attached to the power (cigerett lighter) has a fuse, plus 4 bare wires. The white one is not in use and the other three are connected to my DSC radio,which gives me my position on the radio. I have a cable with one side a usb plug which I can connect to the laptop,the other side has 4 bare wires white red green and black, I thought that I could solder two of the wires straight to the 2 wires that went to the DSC radio,if so how, and if not ,then what to do?

Yes, you can. The trick is to check the wiring diagram for the garmin 72 as well as the wiring diagram for the cable with the USB plug. Unfortunately there's no standard for wiring colours for RS232 cables, only a standard for pins on a 9 pin or 25 pin serial port. So you need to check the manual or other information that came with the garmin as well as the USB plug.

Most probably the black output of the garmin is the earth. The other two will be red for signal out, and green for signal in, or vice-versa. The signal out wire is the one you want, which should be connected to signal in on the DSC radio. The DSC radio might have its pins labelled or numbered or something, and you can check on the manual for the radio which one of them is signal in.

The USB plug wires will be similar -- probably black for earth but maybe white, probably red for signal out and probably green for signal in. You need to wire black to the signal earth of the garmin, and then the signal in on the USB plug to the signal out of the garmin.

These are 5V signals on each side so you're unlikely to blow anything up by connecting things the wrong way around. If you can't find the documentation to give you a definitive answer try connecting it one way and if you don't get NMEA data on the serial port then try the other ways until you get a success.

[magwas]

Originally Posted by SailingPanacea

We have a "GPS bus". A terminal block that we share the data with a Furuno chartplotter,autopilot, AIS, DSC on the VHF, and position data to the PC.

Is the "GPS bus" a simple set of contacts, or are there some active components involved?

I ask it because although RS232 known to work in setups where there is one sender and more receivers, but doing so is begging for failure.

There are some other issues to consider:

- bare USB cable to connect with RS232 won't work. RS232-USB converters exist within only one little chip, so a thing which looks like a bare cable might have the converter in the connector/cable.

- USB signal level is 5V, while RS232 signal level is 12V, but with 5V is being above the minimum required "1" level. Thus there are a lot of cheap USB/RS232 converters out there which output 5V as "1". When your batteries are low, they will magically discontinue working.

- In a boat it might or might not be a problem: different equipment can utilize ground in different ways (and in a home wiring there can easily be multiple grounds in different levels due to multiple phases), which can lead to ground points being in different voltage level. It means stray current, which can ruin the communication and eats up power.

I guess the bullet-proof solution would be using RS232-RS485 converters with isolated ground and use RS485 at the bus.

I am not an electrical engineer, so there may be errors or omissions in the above.