How to Link NMEA from GPS To RS232 ON PC

Discussion in 'OnBoard Electronics & Controls' started by rich99uk, Jan 11, 2009.

  1. rich99uk
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    rich99uk Junior Member

    I have Navman Chartplotter I want to link The NMEA Out put to My pc via RS232. I know you attach the nmea output from gps to input on rs232 and visa versa but it does not seem to work do i need to do anything with the ground on the rs232 ?

    Many THanks
     
  2. TerryKing
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    TerryKing On The Water SOON

    http://en.wikipedia.org/wiki/RS-232#Connectors

    Has the pinouts for various serial port connectors. So, for a typical 9=pin serial port connector, you'd connect the GPS ground to pin 5 and the GPS NMEA output to pin 2.

    This assumes that the serial port will work OK with TTL (0..5V) levels, which most will. RS232 was originally made to use levels of plus and minus 12 volts, but most modern receivers use a switching point of plus 2 volts or so, and it works for 0 to 5 .

    You might use some terminal program to be sure you are getting characters reeceived before using more complex software.

    Let us know what happens.
     
  3. Guest62110524

    Guest62110524 Previous Member

    ja, terry is right, then check baud rate
    then enable the correct port, used to do this a lot but bit rusty will think on it!!!!
     
  4. rich99uk
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    rich99uk Junior Member

    Thanks Guys I will use hyper terminal just so i can see data is comming accross.
    Does anyone know what the Braud rate/ parity and other settings would be ?
     
  5. CDK
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    CDK retired engineer

    9600 baud, 8 bits, NP.
    The GPS must first be told to use NMEA, the default is Navman's own protocol with much higher baud rate.
     
  6. TerryKing
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    TerryKing On The Water SOON

    Hi CDK. I thought the "standard" NMEA output was:
    Baud Rate: 4800 Data Bits: 8 Parity: None Stop Bits: 1

    So, ??? 4800 VS 9600
     
  7. Frosty

    Frosty Previous Member

    Then the pointer on the screen thinks the input from the nmea through the 232 looks like a mouse. The pointer goes berserk.

    easy to fix ,--google it.
     
  8. CDK
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    CDK retired engineer

    Hi TerryKing. There is an expression for this I think: something with a mouth and a foot.
    You are right of course.
    I've spent so many years between modems, the answer came as a reflex.
    Analog group 3 fax machines use 9600 baud, so did the old genius mouse...
     
  9. rich99uk
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    rich99uk Junior Member

    Thannks guys I have made my cable ill test it tonight and let you know how i get on
     
  10. rich99uk
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    rich99uk Junior Member

    Ok great that works but i have got a problem you guys might be able to help with.
    The first is I Have a Navman 5500 Chartplotter Gps I can Only See one NMEA out Connection this also goes to my vhf as i have a panic button which beems my Gps co-oridnates to the coast guard when in trouble.
    The problem is it will only work with one or the other as in nmea data to my laptop or VHF is there any way of getting them both to work at same time.
    I have another plug on the back of my Chartplotter which in the manual states its can be used for a fuel transduser it looks the same as the main jack would it be the same pin out and have another nmea out that i can use

    Cheers
     

  11. CDK
    Joined: Aug 2007
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    CDK retired engineer

    NMEA data out from the GPS can be hard-wired to more than one device because they are only listeners. You can make a Y-cable with on one side the RS232C plug with data-out, data-in and ground, the other side just data-out and ground to the VHF (the VHF will never talk back to the GPS).
    The fuel transducer plug is wired for that purpose only. It allows the plotter to keep track of the amount of fuel in your tanks if you have entered the tank data in the setup menu and tell it when you fill up. That function is not used by most owners because the transducer is expensive and not very precise.
     
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