Reply
 
Thread Tools Search this Thread
 
Old 03 September 2008, 21:25   #1
Member
 
martini's Avatar
 
Country: UK - Channel Islands
Town: jersey
Boat name: Martini II
Make: Arctic 28/FC470
Length: 8m +
Engine: twin 225Opti/50hp 2t
MMSI: 235067688
Join Date: Jun 2005
Posts: 3,030
Anyone for an NMEA question?

The more I look into NMEA, the more confused I get!

The three connections I want to make are:

1) compass tx > gps rx (compass heading data)

2) vhf tx > gps rx (dsc position data from other vessels)

3) gps tx > vhf rx (broadcast my dsc position data)


The units I have are:
gps - Garmin 5012
vhf - Icom M505
compass - KVH Azimuth 1000


The relevent wire colours etc I have are:

compass tx port = green (+), brown (-)

vhf tx port = white outer sheaf (-), white inner core (+)

vhf rx port = red outer sheaf (-), red inner core (+)

gps tx port = grey (A), pink (B)

gps rx port 1 = white (A), white/orange (B)

gps rx port 2 = brown (A), brown/white (B)

Does anyone fancy having a shot at explaining the required connections to me?! The bit where I get really lost is when some manufacturers use + and - while others use A and B. And I'm not sure whether + goes to - or + etc.

HELP!
__________________
martini is offline   Reply With Quote
Old 03 September 2008, 22:02   #2
Member
 
Bigmuz7's Avatar
 
Country: UK - Scotland
Town: Glasgow
Boat name: stramash
Make: Tornado
Length: 5m +
Engine: Etec 90
Join Date: Feb 2006
Posts: 5,090
Sharing your pain Martini .. the last time I asked the question was on this thread as follows if you havnt seen it already clicky which may offer some help from the boys re colours.. etc
__________________
Bigmuz7 is offline   Reply With Quote
Old 03 September 2008, 22:42   #3
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 5,596
You'll need to read your Garmin manual carefully to see how they have implemented this. For a while now, the companies producing navigation equipment for, lets say, a 'non-commercial application' have used a variation of the RS232 system where ground is used for one side of the connection and anything above about 3.5v is recognised as a 'high'. However, the A - B system swings past 0v so the signal requires a swing from +ve to -ve. From memory, I recall it is an RS422 port and +12v to -12v but that may be brain fade on my part.

Now, I believe Garmin have introduced this into their latest equipment but also continued to implement the old system too so you'll need to check out how they have done that.
__________________
JW.
jwalker is offline   Reply With Quote
Old 03 September 2008, 23:01   #4
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 5,596
Here ya go...
Attached Thumbnails
Click image for larger version

Name:	Garmin A-B wiring.jpg
Views:	245
Size:	49.9 KB
ID:	37333  
__________________
JW.
jwalker is offline   Reply With Quote
Old 03 September 2008, 23:28   #5
Member
 
martini's Avatar
 
Country: UK - Channel Islands
Town: jersey
Boat name: Martini II
Make: Arctic 28/FC470
Length: 8m +
Engine: twin 225Opti/50hp 2t
MMSI: 235067688
Join Date: Jun 2005
Posts: 3,030
That all went completely over my head but thanks! At least I got from the pic that A is + and B is -!
__________________
martini is offline   Reply With Quote
Old 03 September 2008, 23:55   #6
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 5,596
From your description and Garmin's instructions:


For normal NMEA (RS 232)

VHF centre core white to 5012 white
VHF centre core red to 5012 grey
5012 pink n/c
5012 orange/white to ground

I guess the VHF outers will connect together and then to ground (Garmin Black)- Check your VHF fitting instructions.

The 5012 may have another channel also...I'll check.

Edit: 4 receiving ports and 2 transmitting ports. It's all in the installation instructions on pages 15 onwards. If you don't have it, go to Garmin's web site and download a copy.
__________________
JW.
jwalker is offline   Reply With Quote
Old 04 September 2008, 20:58   #7
Member
 
martini's Avatar
 
Country: UK - Channel Islands
Town: jersey
Boat name: Martini II
Make: Arctic 28/FC470
Length: 8m +
Engine: twin 225Opti/50hp 2t
MMSI: 235067688
Join Date: Jun 2005
Posts: 3,030
Thanks JW, between that and other bits of info I've gleaned the diagrams in the Garmin installation manual are now starting to make sense!

I am starting to wonder though if the gps will accept heading input from the compass, I can't find any mention in the book of the appropriate nmea sentences.

Does anyone else have an electronic compass hooked up to a gps?
__________________
martini is offline   Reply With Quote
Old 04 September 2008, 22:26   #8
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 5,596
Quote:
Originally Posted by martini View Post
Does anyone else have an electronic compass hooked up to a gps?
Yup, I do. It's a fluxgate compass which is part of my auto pilot and I have also fed its output into my Raymarine radar/plotter so that MARPA will work (requires heading data.) I've not fed it into a Garmin unit but it is mentioned in the 5012 manual. I noticed it last night when looking up your other stuff.
__________________
JW.
jwalker is offline   Reply With Quote
Old 04 September 2008, 22:32   #9
Member
 
martini's Avatar
 
Country: UK - Channel Islands
Town: jersey
Boat name: Martini II
Make: Arctic 28/FC470
Length: 8m +
Engine: twin 225Opti/50hp 2t
MMSI: 235067688
Join Date: Jun 2005
Posts: 3,030
Thanks, I'll go back and have another look. I haven't got MARPA or autopilot, just thought it would be more accurate than gps fix at slow speed/stopped. Also less confusing if my chart is in head up orientation.
__________________
martini is offline   Reply With Quote
Old 04 September 2008, 22:39   #10
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 5,596
Quote:
Originally Posted by martini View Post
... just thought it would be more accurate than gps fix at slow speed/stopped.
Nah, not unless it's flat calm cos the fluxgate rocks all over the place trying to keep up with the boat's movement.
Quote:
Also less confusing if my chart is in head up orientation.
Do you really intend to use that mode?... Anyway, if you're pretty much electronic navigation, you'll likely have all your stuff set to true north so inputting magnetic north will befuddle yer brain at a crucial moment!
__________________
JW.
jwalker is offline   Reply With Quote
Old 04 September 2008, 22:50   #11
Member
 
martini's Avatar
 
Country: UK - Channel Islands
Town: jersey
Boat name: Martini II
Make: Arctic 28/FC470
Length: 8m +
Engine: twin 225Opti/50hp 2t
MMSI: 235067688
Join Date: Jun 2005
Posts: 3,030
Quote:
Originally Posted by jwalker View Post
Do you really intend to use that mode?...
No! Never have done, prob never will More a case of having 2 wires and wanting to connect them to something!

Although I do have a drift fishing spot thats often out of sight of land, when you get to the end of the drift and want to head back to the start point you have to drive off in any direction and wait for the gps to compute a heading. Would be nice to know which way before you set off.
__________________
martini is offline   Reply With Quote
Old 04 September 2008, 22:58   #12
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 5,596
Quote:
Originally Posted by martini View Post
...when you get to the end of the drift and want to head back to the start point you have to drive off in any direction and wait for the gps to compute a heading. Would be nice to know which way before you set off.
Make sure 'tracks' are set to on and you'll know where you are and where you've been...a Garmin unit is spookily good at knowing which way you are pointing. Just follow them home.
__________________
JW.
jwalker is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




All times are GMT. The time now is 22:02.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.