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Old 18-07-2012, 05:25   #1
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No longer receiving AIS information - but why?

Hi All: I have been struggling with this for about one month now and need some fresh ideas as to where the problem might lie. I have had AIS information running on both laptops, but this is no longer the case.

Problem: On the two laptops running Open CPN, neither will display any AIS signal (which I can see from my cockpit, so I know they are in range).

Two laptops:
Win 2000 running Open CPN version 2.5.0
XP running version 3.0.2 (recently upgraded to see if the problem disappeared)

Both will boot up without any COMM recognition problem. On both, the AIS button is live, but when requesting a listing I receive a blank greyed out list. Nor are there any vessels displayed on the chart.

The ACR Cobham Nauticast AIS Receiver indicator LEDs are blinking away conveying that signals are being received and communicated to the laptops. I switched VHF antennas feeding the AIS to verify and no difference.

Can anyone offer some bright ideas as to where my problem lies?
- a defective AIS receiver?
- COMM port connectivity?
- something I have inadvertantly changed within Open CPN

This feature really eased the stress when crossing a heavy traffic separation zone here in the Med, so I want it back.

Thanks for any help......Mike
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Old 18-07-2012, 06:27   #2
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Re: No longer receiving AIS information - but why?

Mike...
Your problem can be caused by pretty much anything, post your logfile and record the NMEA stream you get from the AIS receiver so that we can have a look.

Pavel
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Old 18-07-2012, 09:49   #3
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Re: No longer receiving AIS information - but why?

Hi Pavel:
The logfile I can do, but I frankly can't find any reference in the Forum or Open CPN as to HOW to capture the AIS data stream. Is another piece of software required to enable this capture? If you are familiar with a posting outlining the process could you please flag it for me. Thanks..........Mike
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Old 18-07-2012, 10:03   #4
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Re: No longer receiving AIS information - but why?

Mike download and install the VDR plug-in aka 'Voyage Data Recorder'. Then you should be able to capture NMEA and AIS data and post it here.

Dirk

Edit: The plug-in needs opencpn 2.6 or later ...

Edit 2: whatever tool you use to capture the AIS stream, look for lines starting with "!AIVDM", like this:
Code:
!AIVDM,1,1,,A,4030ouAuiq@@br?1OpHGHj700D0D,0*1C
These are strings from a AIS receiver, I just captured this one using the VDR plugin.
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Old 18-07-2012, 10:04   #5
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Re: No longer receiving AIS information - but why?

Mike...
You need to get some serial terminal program to capture what's coming from the AIS port.
I like https://iftools.com/download/wxterm/...-installer.exe, but there are numerous others.

If you were receiving the data within OpenCPN, the Debugger plugin (available from PlugIns | Official OpenCPN Homepage) would show the stream.

Pavel
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Old 19-07-2012, 03:48   #6
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Re: No longer receiving AIS information - but why?

Hello:
As suggested, I have installed OpenCPNDebugger and can see data stream under the NMEA tab, but nothing under the AIS tab - completely blank.

Am I understanding the results correctly? The GPS data stream under NMEA is working well. There is something amiss with the AIS because nothing is being received, even though my AIS engine indicates signals are being received and forwarded to the laptop.

I have swapped USB ports, but the results are the same. I even reinstalled the drivers.

My conclusion from this is that the AIS engine is faulty, because I have the same situation on two separate laptops and I did have it running before.

Do those with experience concurr?
So as not to waste anybody's time, is there any merit in posting the logfile?

Thanks again....Mike
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Old 19-07-2012, 04:28   #7
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Re: No longer receiving AIS information - but why?

Mike...
Might be, but the only thing you proved is that there are no AIS sentences getting to OpenCPN, nothing more, nothing less.
Did you try to capture the NMEA stream from the AIS with the serial terminal? Are you 100% sure that you set the right COM port for AIS? Are you 100% sure that there actually are any AIS targets in range? Are you 100% sure the cables (if any) are OK?
It's easy to make fast assumptions, the problem with them is they are often wrong

Pavel
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Old 19-07-2012, 07:19   #8
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Re: No longer receiving AIS information - but why?

Mike,

To continue Pavel's line of questions, are you sure that the port to which you connect the AIS has the correct baud rate for AIS (I believe 38400) and not the 4800 needed for the GPS?

Klaas
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Old 22-07-2012, 01:08   #9
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Re: No longer receiving AIS information - but why?

Hi Guys:
Thanks for the added thoughts.
To answer Pavels questions:
- capture with serial terminal - I am unable to try that. My AIS engine has a USB terminal and I don't have access to a USB-Serial cable. All my cables have male serial ends
-have the right comm for AIS - no I am not. When I boot Open CPN up and I have the wrong port identified in CPN relative to the cables installed I receive a message that Open CPN could not open that port. So when it boots up without any connection error message, I assume that the correct port for AIS has been selected. Plus the AIS button in the tool box line indicates the AIS is active. Having said all that, the comm port does not appear on the Device manager list - problem?

I have changed the baud rates on the comm ports as I assigned them to the AIS - no change.

AIS targets in range? - as I write this there is a 150 foot+ cruise ship anchored half a nautical mile from me (who should have AIS by law), but I get nothing. The AIS button shows live, but no little green button to indicate message received. I checked to make sure I am not supressing anchored vessels - but I have sailed into an area where there are few commercial vessels - so I am not 100% on this question

100% sure of cables? - never - the cable is hard wired into the AIS engine at on end and the USB connector looks OK at the other.

Am I correct in my interpretation of the use of Open CPN Debugger, that if there were a data stream from the AIS engine, I would see it on the AIS tab, as with the MNEA stream for the GPS?

Going right back to basics - am I missing something in my set-up of AIS
-plug the engine into my laptop
-update the driver used by the engine for XP
-find the COMM port it is using and ensure the baud rate is correct
-CPN AIS button lights up saying it is active and if messages are received a little green dot is added to the button

If Iam checking all the right boxes, I am comming back to a faulty engine, because I had it running on two laptops and now it works on neither.

Any ideas are truly appreciated.

Thanks...........Mike
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Old 22-07-2012, 03:08   #10
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Re: No longer receiving AIS information - but why?

Quote:
Originally Posted by Mike Two Moons View Post
- capture with serial terminal - I am unable to try that. My AIS engine has a USB terminal and I don't have access to a USB-Serial cable. All my cables have male serial ends
By a serial terminal I meant a program like wxTerm I linked a few posts earlier, no extra wiring needed - Run it, connect to the COM port where the AIS should be (at 38400 baud, 8 databits, no parity, 1 stop bit) and have a look if something at all gets out of it.

If the device is http://www.milltechmarine.com/ACR-Na...ver_p_234.html, it also has a NMEA0183 output that I would test before throwing the whole thing out of the window - a $2 serial to USB converter from ebay is certainly cheaper than the whole $200 device...

Good luck

Pavel
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Old 22-07-2012, 04:56   #11
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Re: No longer receiving AIS information - but why?

Quote:
Originally Posted by Mike Two Moons View Post
... the comm port does not appear on the Device manager list - problem?
I jump on this one. One step at a time, lets make sure your com ports don't have some conflicts.

  1. Unplug the USB cable
  2. check the device manager for serial ports before plugging the AIS back in. Show us a screenshot similar to the one attached here.
  3. plug in the AIS-USB cable, wait a few seconds, check the device manager again for serial ports, show us another screenshot.
Dirk
Attached Thumbnails
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Name:	commportdevicemanager.jpg
Views:	108
Size:	72.8 KB
ID:	43833  
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Old 22-07-2012, 05:29   #12
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Re: No longer receiving AIS information - but why?

If the device is indeed the one in nohal's post, it is featured with a FTDI chip to do the USB communication, and indeed has a separate serial input as well a an extra output.
sometimes these extra wires are hidden in the cable, but are easy to find.
Just take apart the transition where USB cable enters the fixed cable of the device.
Brown is TX- and yellow is TX+

Nice about FTDI over other brands, is that this will always get the same comport designation, even if you happen to plug it into a different USB port.
Other brands will assign a new comport in that case.
Also, FDTI's solution is superior to Prolific, but more expensive.

So check whether you have the FTDI driver installed (installation will be done in 2 stages, and requires some user action as far as i know).

Edit:
Datarate should be 38.400.
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Old 03-08-2012, 04:22   #13
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Re: No longer receiving AIS information - but why?

Hi All:
Sorry to take a while to respond to your recent posts. I have not had wifi access out in the islands where we are sailing.

This is in response to LeaseOn Life.
Hi Dirk:

re screen print - after an hour I gave up - I can't get the screen print to appear in this message. it should appear as an attachment

I get no change when plugging the AIS engine USB into the laptop. I did the same thing with a NASA NAVTEX engine I use. I received an audio signal when plugging in the USB connector and the Device Manager updated to reflect the new COMM being used.

This still leads me to thinking that the AIS engine has a glitch. Agree?

Response to Mas3:
This ACR AIS engine does have additional feed wires, but they are to be used for the GPS data feed to the chart reader. I tried for days to get that feed to work and have given up. All written directions refer to connecting to a chart plotter, not to a laptop. Why it shouldn't work, I don't know.
When all was working fine I had a dedicated feed from my GPS to a serial port and the AIS feed into a USB.

Response to Pavel:
Regarding the wxTerminal, just started working at it.
Thanks all..........Mike
Attached Files
File Type: doc device manager1.doc (73.5 KB, 34 views)
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Old 04-08-2012, 05:19   #14
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Re: No longer receiving AIS information - but why?

I happen to have this unit available.
If i can find time to play around, i wil do so and share whatever i find.

My guess now is that these wires aren't RS3232 (laptop/pc communication) but RS485 (industrial comms).
The unit connecting to it will have to use the same type of comms, so maybe an adapter has to be used.
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Old 04-08-2012, 23:04   #15
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Re: No longer receiving AIS information - but why?

Hi MAS3:
I appreciate your offer for help, but I don't think it is taking me in the direction I need to go. The communication wires are for GPS information, which is working fine through a dedicated serial port. I went around the horn with the US distributor and was left with the idea that those wires were for chartplotter connection only and not to a laptop, as I had originally hoped.

BUT, if you get it working as I had hoped, I would certainly appreciate hearing the details.

Thanks again.........Mike
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