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#1
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On Sun, 24 Aug 2014 20:53:00 -0400, "Sir Gregory Hall, Esq."
wrote: That's not what Wayne said. He said, and I quote, "I suspect that if you had reversed the two wires that it would have worked fine." Reversing the *two wires* means connecting negative to positive. === It's important to understand that there is no ground reference implicit with the NMEA 183 interface standard, unlike a battery connection. Therefore reversing the two wires is a perfectly valid approach which probably would have solved your problem. |
#2
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posted to rec.boats.cruising
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On Sun, 24 Aug 2014 22:02:44 -0400, Wayne.B
wrote: On Sun, 24 Aug 2014 20:53:00 -0400, "Sir Gregory Hall, Esq." wrote: That's not what Wayne said. He said, and I quote, "I suspect that if you had reversed the two wires that it would have worked fine." Reversing the *two wires* means connecting negative to positive. === It's important to understand that there is no ground reference implicit with the NMEA 183 interface standard, unlike a battery connection. Therefore reversing the two wires is a perfectly valid approach which probably would have solved your problem. OMG! You are stupid. Here's a clue: The ONLY reason direct current works is when it is able to complete a circuit from the positive terminal of the 12V battery to the negative terminal of the battery. NMEA is but an extension of the mother board circuit in any VHF or GPS. It must be able to complete a circuit from positive to negative. Attempting to run a loop and expecting electricity to flow when there is no means to ground is stupid and that's what you seem to be suggesting. NMEA is more than just wires. It's a circuit board where electricity is only allowed to flow in one direction. It will not work both ways. Sheesh! -- Sir Gregory |
#3
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posted to rec.boats.cruising
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On Mon, 25 Aug 2014 16:16:47 -0400, "Sir Gregory Hall, Esq."
wrote: OMG! You are stupid. Here's a clue: The ONLY reason direct current works is when it is able to complete a circuit from the positive terminal of the 12V battery to the negative terminal of the battery. NMEA is but an extension of the mother board circuit in any VHF or GPS. It must be able to complete a circuit from positive to negative. === Stupid is as stupid does. NMEA 183 does not require a ground reference, just two legs of a circuit. As I understand it, it is sometimes coupled using opto isolators to prevent an accidental/unwanted ground reference. I would direct you to the following sentence found he http://en.wikipedia.org/wiki/NMEA_0183 "Although the standard calls for isolated inputs and outputs, there are various series of hardware that do not adhere to this requirement." |
#4
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posted to rec.boats.cruising
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On Mon, 25 Aug 2014 16:35:43 -0400, Wayne.B
wrote: On Mon, 25 Aug 2014 16:16:47 -0400, "Sir Gregory Hall, Esq." wrote: OMG! You are stupid. Here's a clue: The ONLY reason direct current works is when it is able to complete a circuit from the positive terminal of the 12V battery to the negative terminal of the battery. NMEA is but an extension of the mother board circuit in any VHF or GPS. It must be able to complete a circuit from positive to negative. === Stupid is as stupid does. NMEA 183 does not require a ground reference, just two legs of a circuit. As I understand it, it is sometimes coupled using opto isolators to prevent an accidental/unwanted ground reference. So you have a LED and a photo receptor of some sort. Big deal. Neither of them will work unless grounded. Nor will the two NMEA wires work unless one of them is positive and one of them is negative. I would direct you to the following sentence found he http://en.wikipedia.org/wiki/NMEA_0183 "Although the standard calls for isolated inputs and outputs, there are various series of hardware that do not adhere to this requirement." From the same article: "The NMEA 0183 standard uses a simple ASCII, serial communications protocol..." Serial port circuits don't work without a positive and a negative wire or pin. Just like NMEA circuits don't work without a positive and negative wire. No circuit - no current can flow. -- Sir Gregory |
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