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Old 01-20-2011, 09:40 AM   #1
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Anyone tech savy know the answer?

I don't understand.* I'm in the process of picking out a class A AIS for a commercial passenger vessel.* Several I have looked at still use a serial output. It's the same with a lot of GPS's* Serial ports on computers have gone the way of the Do Do bird, and a long time ago at that!* Why do you think manufacturers continue to use this antiquated standard even on new, state of the art equipment?* Using a serial output requires the consumer to purchase and install additional hardware and software, adding a layer of complexity, cost, and another possible point of failure. I don't get it, any one got any ideas?...................Arctic Traveller
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Old 01-20-2011, 10:22 AM   #2
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RE: Anyone tech savy know the answer?

AC, Digital Yachts has AIS that is connectible via USB cable for computers. It will depend upon how and what you want to connect to. Most manufacturers are now going to N2K connections which can be connected via a Ethernet cable. Chuck
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Old 01-20-2011, 03:03 PM   #3
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RE: Anyone tech savy know the answer?

Chuck, still didn't answer the question. I have always wondered the same thing. There has to be a reason. It must have to do with "multiple channels"....the fact that you have 9 pins(i think) in a serial port might give them the ability to seperate tasks....and that is straight outta my azz ignorance talking!!!!
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Old 01-20-2011, 03:38 PM   #4
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RE: Anyone tech savy know the answer?

There is no international standard for the transmission of GPS data over a USB link.

The 9-pin connector only uses (I am pretty sure) only 4 pins if +V is not needed, it is just that the DB-9 is the standard serial connector.
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Old 01-21-2011, 02:00 AM   #5
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RE: Anyone tech savy know the answer?

Only 3 pins are used on a D9 connector for serial data:

Pin 2: Receive data
Pin 3: Send data
Pin 5: Signal ground
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Old 01-21-2011, 10:25 AM   #6
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RE: Anyone tech savy know the answer?

I still wonder why manufacturers have not switched over to the modern day input / output protocall, USB?* If I had to guess,* I bet it has something to do with saving a few cents on each unit.* Let the consumer spend the extra $15 to $30 so he can hook up the unit and make it work.............................Arctic Traveller
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Old 01-21-2011, 11:46 AM   #7
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RE: Anyone tech savy know the answer?

Quote:
Arctic Traveller wrote:

I still wonder why manufacturers have not switched over to the modern day input / output protocall, USB?* If I had to guess,* I bet it has something to do with saving a few cents on each unit.* Let the consumer spend the extra $15 to $30 so he can hook up the unit and make it work.............................Arctic Traveller
I think there is more to it than that. *There has to be a technical reason. *Serial ports are almost extinct and I would imagine it would cost more to support them than USB. *But again, I have no clue.

*
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Old 01-21-2011, 12:27 PM   #8
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RE: Anyone tech savy know the answer?

For A GPS To Use The NMEA 0183 Interface Standard, The GPS System needs A Serial Port. The NMEA 0183 Interface Standard Is Serial With A Baud Data Rate Of 4,800bps. According to most GPS manufacturers, A USB Interface Port Cannot Support This Standard in the most universally accepted systems. The newer NMEA 2000 standards are different. Chuck
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Old 01-21-2011, 12:58 PM   #9
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RE: Anyone tech savy know the answer?

Like I wrote earlier, the international standard for transmission of GPS data is written for a serial interface, RS422 or NMEA. IEC, IMO, USCG and numerous other alphabet agencies that make the rules on such things have adopted that interface so marine electronics can talk to each other no matter who makes them or where.

NMEA 0183 is written for RS422, not USB.

Since AIS was not invented for and is not required for recreational boats, the interface is made for the users who must install it and it must meet international standards for connectivity and performance.
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Old 01-21-2011, 07:29 PM   #10
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RE: Anyone tech savy know the answer?

Well OK* (I guess)........................Arctic Traveller
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Old 01-21-2011, 09:24 PM   #11
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RE: Anyone tech savy know the answer?

Don't need to take my word for it. Look up IMO, IEC, and USCG standards for AIS connectivity.

No specific connector is required but the communication protocol is written for and approved for serial data, RS422/NMEA 0183.

When you are dealing with the communications and safety equipment on commercial vessels in international service there are very specific standards that dictate exactly how the equipment functions and how it interfaces with other equipment. The individual components and the completed system must meet strict performance standards and individual installation approvals with annual re-certification.
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Old 01-22-2011, 10:00 AM   #12
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RE: Anyone tech savy know the answer?

I have a NorthStar 6000i on my boat and would like to have an AIS (A or B) unit that shows the traffic on my chart plotter. I'm told by my electronics tech (who I respect very much) that I can't do it with my present MFD. Why? Is it* because my unit doesn't conform to NMEA 2000?
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Old 01-22-2011, 10:58 AM   #13
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RE: Anyone tech savy know the answer?

NMEA 2000 is a networking system, NMEA 0183 is a data protocol that uses serial transmission. What you would like to do is like connecting a serial port to an ethernet network without processing the signals so they all look the same to the system.

While you can't connect them directly, there are interface devices available that make the information and connections compatible.

Here are links to a couple of them:

http://www.actisense.com/HTML/Produc...ay_1/index.php

http://www.furunousa.com/ProductDocu...s%20Manual.pdf
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Old 01-22-2011, 01:37 PM   #14
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RE: Anyone tech savy know the answer?

Thanks Rick!* I'll check them out but am wondering why my "tech" didn't point this out. (Wanted to sell me all new NMEA 2000 components??)
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Old 01-22-2011, 01:49 PM   #15
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RE: Anyone tech savy know the answer?

http://www.totalphase.com/support/kb/10048/

Here is a link that expalins the difference between usb and serial devices.* I'm guessing that part of the reason is also with serial to parallel conversion and regulated power supplies.* The data stream exists in the AIS device and can be sent to a serial port, whereas it probably takes another chip to do the conversion to a parallel port, and another voltage pick for the USB port.* My son who is in the OEM electronics business frequently tells me that even in high end electronics, decsions are made on whether to incorporate another 50 cent chip.

While we're on the subject, I also wish someone would produce an AIS with a NMEA 2000 input for GPS.* I have a 32 channel NMEA 2000 GPS, but I would need to add another, lower quality, 16 channel unit because "this is the standard industry spec".* Maybe someday.
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Old 01-22-2011, 03:43 PM   #16
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RE: Anyone tech savy know the answer?

Geez, do parallel ports still exist?
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