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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
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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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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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(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.
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.
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(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?
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(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
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Same issue with the GX2000. I have a Digital Yacht NMEA0183 USB cable, which works fine. When I remove it and connect the radio to the Pican-M, it doesn't work. I have sent some 0183 data back into the pican-m and it does receive, although it's all garbled.
I'm wondering if there is an issue with some drivers. I have a Renogy Commander USB connection that is slightly temperamental. It's plugged into a USB hat and doesn't play very well with others. For now, I've reinstalled the YD usb cable and everything else works great. Pican-M N2K is fast!
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2021-07-15, 07:27 PM
(This post was last modified: 2021-07-15, 09:10 PM by SCarns.)
This question appeared on Slack and the suggestion is that the Standard Horizon uses TTL instead of RS422. In which case, the Pican-M will probably never work for this purpose, at least now without a converter to match the ground referenced data to differential data protocol. There are converters out there, but I just hooked mine back up to my Digital Yachts NMEA0183 to USB adapter (which must use TTL the radio expects) and everything continues.