Nmea wiring question

Mavis

Mavis

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I am awaiting a response to this question from Raymarine and SH - But I thought I would also ask the forum - How do I connect my new Tack Tick T122 wireless interface to my Standard Horizon Cp300 chart plotter so that they may pass nmea sentances between them. I have fitted all the rest of the Tack Tick kit (depth and speed transducers, Hull transmitter and wind instrument) and its all working straight from the box. I understand that the wireless interface will allow other third party instruments such as the SH chart plotter to talk to each other and display shared information.


Tack Tick
NMEA Sentences (0183 V2.30)
Received Sentences: DBT, DPT, GLL, HDG, HDM, MTW, MWV,
RMB, RMC, VHW, VLW, VWR.
Transmitted Sentences: DPT, GLL, HDG, MTW, MWV, RMB, RMC,
VHW, VLW, VWR.
 
Lazy Kipper said:
It gets messy connecting Garmin to Raymarine, Garmin is three wire NMEA and Raymarine as ever is simples.
Click to expand...

I'm a bit surprised at that, though my only experience with Garmin is my ancient GPSs (not charplotters etc). They just have data in and data out which is used for NMEA, Garmin protocol and RTCM, depending on how they are configured.

Mike.
 
Lazy Kipper said:
It gets messy connecting Garmin to Raymarine, Garmin is three wire NMEA and Raymarine as ever is simples.
Click to expand...

Yet another reason for avoiding all this archaic NMEA 0183 stuff and getting NMEA 2000.

We have all Garmin stuff but were forced into stupid Raymarine's autopilot as the Garmin one wasn't available when we needed it. Only two wires were needed.
 
mjcoon said:
I'm a bit surprised at that, though my only experience with Garmin is my ancient GPSs (not charplotters etc). They just have data in and data out which is used for NMEA, Garmin protocol and RTCM, depending on how they are configured.

Mike.
Click to expand...

It was NMEA in, NMEA out and ground on the Garmin side and Raymarine was just NMEA+ and - From memory the Garmin NMEA out and ground and Raymarine NMEA- were all connected together to the ship's battery -ve and the Garmin NMEA out into the Raymarine +ve. It took some fidlin.
 
Lazy Kipper said:
It was NMEA in, NMEA out and ground on the Garmin side and Raymarine was just NMEA+ and - From memory the Garmin NMEA out and ground and Raymarine NMEA- were all connected together to the ship's battery -ve and the Garmin NMEA out into the Raymarine +ve. It took some fidlin.
Click to expand...

I don't suppose shorting out the Garmin NMEA out wire would have done it any harm because there would be circuitry to limit the short-circuit current. Seems a bit brutal, though! (But I think there must be a typo since you have conflicting mentions of "Garmin NMEA out".)

Mike.
 
mjcoon said:
(But I think there must be a typo since you have conflicting mentions of "Garmin NMEA out".)
Click to expand...

:)

Spotted that too, but wasn't going to go into it. Dunno what was supposedly so difficult about making that connection, seems perfectly clear to me.

Pete
 
mjcoon said:
I don't suppose shorting out the Garmin NMEA out wire would have done it any harm because there would be circuitry to limit the short-circuit current. Seems a bit brutal, though! (But I think there must be a typo since you have conflicting mentions of "Garmin NMEA out".)

Mike.
Click to expand...

I'm working from memory:

Garmin NMEA-ve
Garmin NMEA ground
Raymarine NMEA-ve

All three also connected to ship's battery -ve

Then simply Garmin NMEA+ to Raymarine NMEA+
 
Lazy Kipper said:
I'm working from memory:

Garmin NMEA-ve
Garmin NMEA ground
Raymarine NMEA-ve

All three also connected to ship's battery -ve

Then simply Garmin NMEA+ to Raymarine NMEA+
Click to expand...

Ah, that is exactly the distinction I was wishing to make; whether the Garmin connections are balanced or not. "+" and "-" implies they are. Whereas my connections are most definitely in and out unbalanced (because I hold "conversations" in Garmin protocol). Although NMEA 183 is normally emitted on the data-out line, I think there may be proprietary Garmin-NMEA sentences that it accepts on its input line too.

Mike.
 
mjcoon said:
Ah, that is exactly the distinction I was wishing to make; whether the Garmin connections are balanced or not. "+" and "-" implies they are.
Click to expand...

It's quite likely that there is a single "NMEA negative" shared between all the in and out connections, though. My Standard Horizon radio for instance has three NMEA channels (one in for position, one slow out for DSC messages so mayday vessels appear on a compatible plotter (which I don't have), and one fast out for AIS messages) and one wire for a shared negative. I'm not sure if that really counts as a balanced pair.

Pete
 
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mjcoon said:
Ah, that is exactly the distinction I was wishing to make; whether the Garmin connections are balanced or not. "+" and "-" implies they are. Whereas my connections are most definitely in and out unbalanced (because I hold "conversations" in Garmin protocol). Although NMEA 183 is normally emitted on the data-out line, I think there may be proprietary Garmin-NMEA sentences that it accepts on its input line too.

Mike.
Click to expand...

It doesn't matter whether they are balanced or not, you just connect the - and ground together when connecting to an unbalanced input.
The reason for the balanced version is just to separate the output's current return from the ship's ground to reduce the chances of noise on this corrupting the output and enable the ground to be connected to the screen where screened cable is used. On leisure vessels (short cable runs) the need for balanced working is not really necessary.
 
ianj99 said:
It doesn't matter whether they are balanced or not, you just connect the - and ground together when connecting to an unbalanced input.
The reason for the balanced version is just to separate the output's current return from the ship's ground to reduce the chances of noise on this corrupting the output and enable the ground to be connected to the screen where screened cable is used. On leisure vessels (short cable runs) the need for balanced working is not really necessary.
Click to expand...

Quite. The important thing is not to confuse + vs - with in vs out. Orthogonal.

Mike.
 
Following up to say all now working correctly. The slight thread drift re Garmin and Raymarine, while interesting was not relevant to my problem. I spent a an hour or two on the web reading about and understanding NMEA, and then took Nigel’s advice and gave it a go – The point is, it’s far better to learn and fully understand your boats systems and do it all yourself. Then when it all goes tits up at sea you can deal with it.
Peter
 
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