AIS installation- Open CPN and Ubuntu

[Tia Bu]

I'm running Open CPN on a Dell notebook with Ubuntu Linux. I use a USB GPS puck. It all runs great. This weekend, I tried to hook up a used Nobletec 100 AIS receiver via the 9-pin serial port. I couldn't get it to work.

I'm beginning to think the problem might be in the baud rates of the two NMEA streams. The GPS transmits at 4800 baud. When I click on the "GPS" tab of the "Tools" menu in Open CPN, I can then open up the NMEA data stream box and see data streaming in from the GPS. When I unplug the GPS and leave the AIS receiver plugged in, no data streams through the window.

I know that the AIS receiver transmits data at 38,400 baud. As far as I can see, there is no window available in Open CPN to see the AIS NMEA data stream. Or would that data appear in the same window as the GPS data stream if I had it all set up correctly? Do I need to change the settings of the serial port in Linux? If so, how would I do that? (Of course, it's possible this receiver isn't transmitting data, but I can't find a way to confirm or deny this at this point.)

In the "GPS" tab in Open CPN, when I look at ports available, I see three COM ports (they're called something like "tty" in Linux). I also see a "tty" port that ends in "usb" (this is the one that the GPS works on). I also see a "shared AIS/GPS port" selection.

In the "AIS" tab, I only see the three COM ports listed. The USB port and the shared AIS/GPS port don't show up.

Does this make any sense to those of you who know the inner workings of the Open CPN program? Am I doing something wrong?

Ideas for a fix?

Thanks in advance.

[balp]

Originally Posted by Tia Bu

I know that the AIS receiver transmits data at 38,400 baud. As far as I can see, there is no window available in Open CPN to see the AIS NMEA data stream.

On linux i only used OpenCPN against gpsd my self, for confuguring the serial port there is an command line utility setserial that can fix this outside opencpn.

sudo apt-get install setserial

to install on ubuntu/debian.

Maybe that can help you.

[Tia Bu]

That helps some. Thanks. Does anyone out there know if the AIS NMEA data and the GPS NMEA data have to come in to Open CPN through the same port?

Do they have to come in at the same baud rate?

Or can one come in through USB and the other through a serial port at different baud rates?

If they can come in through different ports, is there some way to see the AIS data stream in Open CPN or Ubuntu?

[SethDart]

I'm using Fedora with a USB for AIS+GPS.

So my settings are:
- GPS > NMEA Options > NMEA Data Source = AIS Port (Shared)
- AIS > AIS General > AIS Data Port = /dev/ttyUSB0

There's never any "AIS shared" port in AIS settings. If your GPS comes with AIS input, you select that port into AIS settings and your select "AIS Shared" in GPS settings as described above.

If I understand your configuration,
- you've GPS coming from USB so the setting should be /dev/ttyUSBxx
- you've AIS coming from 9 pin COM port so the setting should be /dev/ttySxx
(xx being 0, 1 ore more depending on your hardware)

It should work without changing any setting for the COM port (with setserial)
Check opencpn log to see if the device opening failed.

PS : Even if the device is not listed in the drop down list, you can use whatever dev is appropriate for you, just type in the device full path: eg. /dev/ttyS6

[Tia Bu]

Many thanks.

I take it from your response that there is no way to see the AIS data stream in real time? I just tried opening my opencpn.log file, but the data there seems to be a couple of months old.

[Tia Bu]

Well, I'll try to answer my own question, since this forum is kind of the help desk for Open CPN, and maybe this will be of use to someone else later.

Is the Linux command "cat dev/tty##" a way to see the AIS data stream coming in through nine-pin serial port, where "##" is the number of the port?

I haven't gotten back to the Linux machine to try it yet.

[mrm]

Originally Posted by Tia Bu

Well, I'll try to answer my own question, since this forum is kind of the help desk for Open CPN, and maybe this will be of use to someone else later.

Is the Linux command "cat dev/tty##" a way to see the AIS data stream coming in through nine-pin serial port, where "##" is the number of the port?

I haven't gotten back to the Linux machine to try it yet.

I believe I have seen this cat /dev/ttyXX method mentioned on OpenCPN web page somewhere, but, if you would like a bit more comfort, install Minicom package. It will give you a nicer interface to see what is transmitted on serial links.

[SethDart]

"cat" doesn't work for a device, only for files. You shall use minicom.

First, install minicom

~$ sudo apt-get install minicom

Then run it

~$ minicom -s

Select "Serial port setup"
Change "Serial device" to /dev/ttyUSBxx or /dev/ttySxx, hit enter, and enter again
Select "Exit" - hit enter

Now you shall see output from your COM/USB port.

To exit, hit Ctrl-A then X

[mrm]

Originally Posted by SethDart

"cat" doesn't work for a device, only for files.

With respect, I differ.
In UNIX, the "everthing is a file" paradigm is universally employed and /dev/ttyXX is nothing but a special file. Problems may arise from incorrect user access permissions or the serial port hardware (driver) set to wrong defaults, like expecting hardware flow control. This is controlled via a set of dedicated IOCTL calls and can be set from userland by applications like setserial. Or, to have an easy, single step solution:

You shall use minicom.

as I already suggested.

Alternative, and preferred in case a bi-directional connection is made, method of leaving Minicom would be to hit Ctrl-A Q. This avoids transmitting modem reset sequences down the serial link. Also:

Ctrl-A O brings a configuration dialog

Ctrl-A P brings a serial comm parameters setup dialog

[cagney]

cat /dev/tty/USB0 works out of the box on Ubuntu 1010,... kind of. It prints between 0 and 10 lines before exiting. Same thing for "more" or "less".

To see a continuous readout, with some funny line brakes, try this one-liner.

while true; do read -n 80 LINE < /dev/ttyUSB1;echo $LINE; done

Stop with CTRL+C.

This is all you need, to see if your device is working and to identify the NMEA sentences.

Thomas

[Tia Bu]

Thanks, all. This helped isolate the problem. It looks like the AIS receiver is not sending out data. Will have to get another one.

Hope this thread is of use to someone else in the future.

[HamishB]

fwiw "gtkterm" is a fine replacement for minicom.

Hamish