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Connecting GX2100 to pican-m
#1
Folks:

My Raspi 4 is extended with a pican-m HAT. Connection to NMEA2000 - send and receice - is working well. I am struggling with connecting to my Standard Horizon GX-2100 vhf to send position and SOG using the rs422 screw connector of the pican-m.

Everything seams to work fine but the GX-2100 does not recognize the data.

I am using the signalk-to-nmea0183 plug-in to and selected to send GLL, GGA and RMC sentences. These sentences originate from OpenCPN where a UDP Connection is used to transfer them to signal-k. The data can be seen in the signal-k serial stream log and can be captured from from my windows-pc when I conncet it to the rs422 screw connector instead of the vhf.

The "strange" behaviour is, that the NMEA sentences are received in chunks of exactly 512 bytes with a 5 seconds delay between them. This implies that the last sentence is never complete unless the 512 byte chunk directly ends after the sentences cr+lf characters.

I would expect that the pc receives the data "as sent" without delay and without cut in chunks and I wonder if this is the reason for my problem. Does the GX-2100 drop the received data when the last sentence of a chunk is incomplete?

Question: How can I convince the Raspi/pican HAT to sent every sentence immediatly after it was emitted by signal-k?

Best Regards
Michael

SY Neptune's Car
Sigma 33 OOD
DG3612
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#2
Interesting as I have a GX-2100 and have not been able to get the GPS in to work, nor the AIS out to happen in a similar configuration. Hoping to see an answer on the chunking.
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#3
Just out of curiosity, what happens when you plug that RS422 converter back into your PI and look at that port? You could do it with "cat /dev/tty<whatever the port is>". The reason I ask is that I"m wondering if the chunking you are seeing is actually a Windows thing rather than the data coming out of the SignalK server.
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#4
(2021-06-10, 04:09 PM)abarrow Wrote: Just out of curiosity, what happens when you plug that RS422 converter back into your PI and look at that port? You could do it with "cat /dev/tty<whatever the port is>". The reason I ask is that I"m wondering if the chunking you are seeing is actually a Windows thing rather than the data coming out of the SignalK server.

Keen idea, but I do not have any more serial ports available. Sad
I believe it has to do with some send buffer size configuration.

The same happens when I create a serial connection directly in openCPN.
Do both programs simply do not flush the send buffer after each sentence?
But can that be? Serial communication might be relatively new to signal-k but its mature in openCPN.

SY Neptune's Car
Sigma 33 OOD
DG3612
Reply
#5
(2021-06-10, 04:09 PM)abarrow Wrote: Just out of curiosity, what happens when you plug that RS422 converter back into your PI and look at that port? You could do it with "cat /dev/tty<whatever the port is>". The reason I ask is that I"m wondering if the chunking you are seeing is actually a Windows thing rather than the data coming out of the SignalK server.

You are perfectly right. The problem is was Windows the type command. I switched over to putty and I am getting the sentences line by line as expected.
Conclusion: Do not use "type com1" to test anything on Windows serial ports.

But the question still is: What is wrong with the GX-2100?

SY Neptune's Car
Sigma 33 OOD
DG3612
Reply
#6
(2021-06-10, 03:57 PM)SailAlpha Wrote: Interesting as I have a GX-2100 and have not been able to get the GPS in to work, nor the AIS out to happen in a similar configuration.  Hoping to see an answer on the chunking.

SailAlpha:

It's all up an running. How that? Here is the story:

At Standard Horizon they have at least one color-blind production worker: The documentation says the calble coded green is ground, the blue one is nmea in+. On my one these calbles are inverted (blue = ground, green = in+). That's why the correct sentences emitted by signal-k have not been read - in my case.

Have you tried this?

Best regards
Michael

SY Neptune's Car
Sigma 33 OOD
DG3612
Reply


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