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Old 11-11-2013, 07:42   #1
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NMEA output problems

I have OpenCPN 3.2.2 running on Window 7 Starter on a netbook connected via two serial ports to a VHF/AIS and a Tacktick NMEA hub. The AIS is functioning perfectly on COM4 but the COM3 connection works on input mode only. As soon as I check the 'output on this port' box OpenCPN loses position data.

Looking at the nmea debug window shows everything working without the output on COM3 but then with the 'output on this port' box checked there are numerous red sentences, plus the position symbol goes red.

If anyone can help me I may not go crazy... Thanks!
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Old 11-11-2013, 08:22   #2
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Re: NMEA output problems

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Originally Posted by elhix View Post
I have OpenCPN 3.2.2 running on Window 7 Starter on a netbook connected via two serial ports to a VHF/AIS and a Tacktick NMEA hub.
Please tell us more about your netbook and it's serial in's, cos I haven't seen any recent laptop or netbook with actual serial inputs. Usually one uses a serial to USB adaptor.
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Old 11-11-2013, 08:40   #3
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Re: NMEA output problems

Sorry, yes I have two usb- serial adaptors.

I had this system running with opencpn 3.2 last year with no problems on another netbook. I just tested that netbook (which now also has opencpn 3.2.2) and found exactly the same problem.
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Old 11-11-2013, 09:01   #4
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Re: NMEA output problems

Thanks. There's the possibility that the two USB-serial adaptors are competing for the same port or otherwise colliding... could be driver-related.

There might be a way in the driver or system config to force the USB adaptor COM ports to a higher number. I think my USB-serial adaptor shows up on COM6.

Enlighten us - why do you need two NMEA ports on the netbook? Can you not just take a single NMEA output from after the hub, which should take care of merging the GPS and AIS data?

As a general principle, I aim to have the fewest possible connections running to a laptop. (0 - wireless is ideal )
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Old 11-11-2013, 09:40   #5
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Re: NMEA output problems

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Originally Posted by Lake-Effect View Post
Enlighten us - why do you need two NMEA ports on the netbook? Can you not just take a single NMEA output from after the hub, which should take care of merging the GPS and AIS data?

As a general principle, I aim to have the fewest possible connections running to a laptop. (0 - wireless is ideal )
The AIS input comes in from the VHF/AIS at baud rate of 38400, the input from the nmea hub has a baud rate of 4800.
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Old 11-11-2013, 13:17   #6
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Re: NMEA output problems

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Originally Posted by elhix View Post
The AIS input comes in from the VHF/AIS at baud rate of 38400, the input from the nmea hub has a baud rate of 4800.
I can't find a good manual for the T122, but I would have expected a modern hub to merge the NMEA data regardless of different rates. Alternatively maybe you can change one of the rates (eg change the AIS data rate to 4800).

I don't have one hooked up right now, but if you can see both serial-USB interfaces in Window's device control panel, you can possibly force them to separate COM ports.
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Old 11-11-2013, 13:26   #7
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Re: NMEA output problems

Sorry, you cannot have AIS at 4800 - it is too slow for the data stream, and will cause data loss.
Try the com 3 adapter alone - same problem? Try the com 4 adapter alone - same problem?
Do you have the latest drivers for the USB-Serial adapters?
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Old 11-11-2013, 14:59   #8
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Quote:
Originally Posted by NZ8720
Sorry, you cannot have AIS at 4800 - it is too slow for the data stream, and will cause data loss.
Try the com 3 adapter alone - same problem? Try the com 4 adapter alone - same problem?
Do you have the latest drivers for the USB-Serial adapters?
You may be getting an irq clash try changing the irq to a unique number 3 or 4 could be good. This is done in device manager. Each serial port must be on its own irq
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Old 11-11-2013, 20:56   #9
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Re: NMEA output problems

elhix...

Can we see a screen shot of the NMEA debug window (showing RED faults), and your Connections dialog settings?

Thanks
Dave
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Old 12-11-2013, 00:48   #10
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Re: NMEA output problems

Thanks for the input everyone. I'm currently enroute to Gibraltar but when we arrive - and have internet - I'll get some nmea samples.
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