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  #11  
Old 04-15-2010
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Thanks, SD, I'm rapidly coming to that conclusion too. It appears that both units are functioning as they should...just don't play well together.
I will see what's involved with upgrading the firmware...not holding my breath, though...the GP-31 is a discontinued product.
hk
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Old 04-15-2010
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You might luck out...they may have a newer firmware available for it that you just haven't updated to yet.

Good luck.

Quote:
Originally Posted by thekeip View Post
Thanks, SD, I'm rapidly coming to that conclusion too. It appears that both units are functioning as they should...just don't play well together.
I will see what's involved with upgrading the firmware...not holding my breath, though...the GP-31 is a discontinued product.
hk
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Old 04-16-2010
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I second SD, it might be a nmea version. Check also what is possible for communication settings like baudrate, stop bits, parity, etc .. to match each other. Should be simple, very simple indeed.
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  #14  
Old 04-18-2010
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Part of the problem here is the confusion over NMEA and RS232, 422, or whatever.
When you send NMEA data to a device, those data come FROM the NMEA output, +, or -, to a NMEA input, + or -. NMEA is NMEA, NOT RS anything. Serial communications protocol specs...baud rate, stop bits, etc. have no meaning whatsoever.
Yes, you can convert, but you can't just plug an NMEA output into an RS input or vise-versa no matter how you jiggle the wires.
Howard Keiper
Berkeley
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Old 04-19-2010
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Quote:
NMEA is NMEA, NOT RS anything
Quoting from the NMEA 0183 version 2.20 standard:
"The drive circuit used to provide the signal 'A' and the return 'B' shall meet, at a minimum, the requirements of EIA-422-A (December 1978)". So in fact NMEA 0183 (from version 2 onwards) follows the RS-422 standard specifically.
The confusion comes because version 1 was based on RS-232 but with a wider voltage range. RS-232 uses ground as the return path while RS-422 uses a dedicated return path typically labelled 'B'.
This makes connection of devices following the different versions more difficult. It is further complicated with some devices having the required opto-isolated inputs and others not.
Another problem is most manufacturers don't bother informing the user which version they are following and even cherry pick the cheapest option from each version. Just because it is brand new does NOT mean it follows the latest version of the standard.

Quote:
Yes, you can convert, but you can't just plug an NMEA output into an RS input or vise-versa no matter how you jiggle the wires.
I do this almost every day without the need to jiggle anything, I just plug them straight in. Remember that a 'B' of a talker should NOT be connected to the ground of a listener.
Modern RS232 chips work beyond the spec and can cope with RS422 signals. I have never yet found an RS232 connection not to work with an RS422 (NMEA 0183) input but it is not guaranteed. Also, due to the change of spec between version 1 and version 2 the latter versions are required to cope with voltages above the RS422 so they can handle direct (un-converted) RS-232 inputs as well. The only thing to watch out for is ground loops.
The information in NMEA 0183 is basically just text so if you are only interested in the data then it doesn't matter which RS standard you follow to get the text from one place to another (for instance Airmar smart transducers use RS-485 to transmit NMEA 0183 sentences).
If you are not sure about you connections ask in the forum and someone will OK it for you.

-Howard
With both devices using A and B signals that is not your problem, both are following later than version 1, for the voltage levels at least.
Quote:
going (from 0) pulses, 2V ..... I took the measurements at the input plug of the h3000
It sounds like you took the measurement across the A and B not across ground and A, can you confirm this? How did you measure the voltage? Using a meter on an active signal line is not always accurate.
When you had the h1000 connected was that using A and B for inputs or was it A and ground? Connecting a driving B signal into ground could have worn out the driver circuit of the Furuno. You may be able to rescue the situation using an isolating buffer box that can handle the low 2v input signal boosting it for the H3000 to read.
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Old 04-19-2010
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Wow, I stand corrected...many times over. I wish you'd been around last week. Yours is the most authorative info I've gotten on the subject since I got into my situation...that includes advice from Furuno and B&G.
Anyway, the fellow from B&G was being very helpful or trying to be, sensing (correctly) that I was not getting anywhere and told me with equal vigor that I was barking up the wrong tree...that the h3000 expected data from the GPS to be delivered to the NMEA IN jack. There are only two wires, and that the + out from the GPS should go to the + IN terminal. Well, OK, but it doesn't work. That's when the discussion got around to what a dope I was and maybe I got the NEMA jack and RS232 Jacks confused. I concluded that he was at least partially right.
I didn't mean to sound like I had the last word, and I apologize for that.

Howard Keiper
Berkeley
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Old 04-26-2010
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No worries Howard, you just sounded frustrated, didn't sound like it needed an apology at all but thanks all the same.

Our NMEA 0183 information sheet, containing everything we are allowed to give away regarding NMEA 0183, has been linked to by eherlihy in this thread (I can't link to it because of my commercial interests).
The thing with having to pay for standards is most people don't buy them so don't know what's in them.

I hope you have got everything sorted out now.
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Old 04-26-2010
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As it worked out, B&G had a big presence at the Strictly Sail Show, here in Oakland, and their senior tech, one Matt Fries, was there too. The owner of the boat in question and Matt discussed the situation and both Matt and another tech visited the boat. It turns out that they felt there was enough reason to replace the CPU. The exchange should be complete by the time I finish this.
Talk about customer service...wow.
Howard Keiper
Berkeley
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Old 05-14-2010
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I was interested in the comments "redline" made regarding the nature of the ST60 Multi's NMEA out signal. I also observed a +12 on the NMEA+ with a small drop every 2 sec when data is being output. If I connect the NMEA+ and NMEA- directly to a serial to usb adapter no rs232 data is present (this discussion thread explains why). I ultimately want to use the ST60 Multi as a low cost seatalk to NMEA repeater for the instrument messages it does output. I want to connect to an RS232 serial to usb device (IOGear GUC232A) and read the NMEA messages with software I am developing.

I was wondering if there was a simple circuit that would convert the ST60 Multi output to an RS232 signal which could be read by the serial/usb device. Of course I can go get a Raymarine E85001 or a special opto-isolator cable (cost almost as much as the E85001) or even a nice Brookhouse NMEA Multiplexer, but for now I was looking for a low cost simple solution.

I would appreciate any good ideas that would help.

Thanks,

Jim
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Old 05-14-2010
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Jim, I did have some success connecting the ST60 Multi's NMEA+ to RS232 RXD and NMEA- to RS232 GND, *AS LONG AS* the computer was ungrounded. See Actisense's comments regarding not grounding the NMEA- in most cases. With the laptop on batteries or even its AC adapter, it worked fine. However when I plugged the laptop into another device on ship's DC, no more NMEA from the Multi.

Perhaps the IOGear is floating wrt ground (we wish) or you could try the Digital Yacht usb-serial-NMEA reviewed on Panbo:

Panbo: The Marine Electronics Weblog: DY NMEA 0183 to USB, looks handy

List price is about double the IOGear but you'd avoid another adapter.

For a time I used a Noland N183-41 NMEA multiplexer, (discontinued version, borrowed from a friend) which took NMEA in and provided a floating NMEA output as well as RS232. You might find something like that on eBay.

Eventually, I broke down and got the Raymarine E85001... it has the advantage of providing many more sentences, as well as NMEA and RS232 out.

edit: Come to think of it (and re-reading your question), a simple circuit for that application could be simply an Opto-isolator, with a 1K resistor in series with the input/NMEA side (the Multi itself uses 4 2.2k in parallel in series with a PC357 opto) then the opto collector to +12 (with another 1k or so in series for good measure) and the opto emitter to RS232 in. You might need a 10k pulldown or so on RS232, but usually switching from open circuit to +12 would work even without a negative source.

I hope this verbal schematic makes sense, if so it's only about $5-10.
I'm off to bilgeclean and bottompaint but would be delighted to prototype the circuit, test and tweak the resistor values in exchange for help with 46' of wax job. ;-)
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Last edited by redline; 05-15-2010 at 09:33 AM. Reason: add opto circuit
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