Linking NMEA instruments to PC running OpenCPN

[MILLPOND]

Apologies if this has been covered elsewhere, but I want some advice.

I have recently set up OpenCPN on a laptop with a separate BU353 GPS receiver. It works really well and I am delighted.

I now want to add AIS, and at the same time replace my old non-DSC VHF.

I think I want to buy the Standard Horizon GX2100E combined VHF and AIS receiver. I will connect this to my existing Garmin GPS152H. But I need to know how to link this to the laptop to show AIS information on the chart plotter. As far as I can work out I need some sort of USB NMEA gateway. But how does this connect into the back of the VHF/AIS - is it a simple plug or do I need to connect individual coloured wires? What is the best product to buy?

Sorry to ask a question which to many is probably very obvious, but advice from someone with experience would be appreciated.

Thanks!

On a similar note, has anyone got the SH GX2100E, and how does it perform?

 

[laika]

You need to take a second set of wires (in addition to the ones to your garmin) from the GX2100E. Lazy people like me would use choc block connectors in a dry part of the boat (one wire enters, two wires leave to completely misquote "Beyond Thunderdome"). Others will rail against them.

Your easiest option is to attach them to an rs422 to usb converter (£11 delivered from ebay). You could probably also use a more easily obtainable rs232 to usb converter, but then you'd have to solder up the wires to a couple of pins on a 9 pin serial socket

 

[saltylegs]

Which pins do you need to connect to?

 

[laika]

If you're just using the AIS as input to opencpn (ie not bi-directional) you only need 2. A quick google of the gx2100e suggests brown (NMEA-HA +) to pin 2, green (NMEA common) to pin 5, but I always get confused between front/back views of male/female DB9s, especially close to midnight with the benefit of a few pints, so google "DB9 pinout" to double check. Your mission is to connect "NMEA common" to rs232 ground and the 38.4kbaud nmea + output to the rx on the serial to usb converter.

 

[saltylegs]

thanks good starting point.

 

[Baggywrinkle]

Here is the wiring diagram from my boat .....

My OpenCPN GPS signal is from the plotter and AIS from the VHF. They are different baud rates so the USB dongle creates two virtual com ports on the PC. Works a treat, wire colours are correct for the SH components.

COM1 on the diagram provides the AIS feed to OpenCPN and if you have a plotter to provide GPS then COM2 provides GPS to OpenCPN. The laptop then doesn't need its own GPS receiver so the GPS dongle can be retired to a backup.

The DeLock 61886 is a dual serial to one USB converter and makes for a very neat solution if you install two permanent serial ports at the chart table.

 

[MILLPOND]

Great diagram, thanks for that Baggywrinkle. It looks like a good solution. Are you able to send a waypoint from OpenCPN directly to the chart plotter?

How does the GX2100E perform - what sort of range do you get on AIS ship location?

 

[Martin_J]

Following on from baggywrinkle's reply above... His choice of USB to Serial cable is good. Go for any make that is based on the FTDI rather than the Prolific chipset if at all possible... They tend to work more reliably with most versions of Windows.

 

[Baggywrinkle]

Works nicely, I can send waypoints and routes to the plotter from OpenCPN but due to differences in the waypoint naming abilities of the plotter and OpenCPN they don't always retain the same name. One thing that did disappoint was sending recorded tracks from the plotter to OpenCPN. The plotter will not export tracks over NMEA AFAIK.

The process is to put the plotter in "recieve mode" and then export the waypoint or route from OpenCPN - a bit of a pain as it means setting up the plotter in the cockpit, then going to the chart table and exporting from OpenCPN, then back to the plotter - but it works.

AIS performance, very happy. We see ships in the traffic seperation zone in the middle of the Adriatic from the islands in Istria - 20-30 Nm seems to be no problem. We watched the yacht 'Follow Me V' closing in on us at the weekend, speed 12 Knots, CPA 0,01 Nm and knew it was heading straight for us even when it was a little white dot - bright sunshine and great vis. Sure enough the little triangle worked it's way across the plotter screen, counting down the minutes to collision. We were sailing and he altered course and passed us at maybe 300-400 metres, don't know if we showed up on his radar and we have no AIS transponder. Does just what it says on the tin and we were aware of his course and kept checking on his progress.

Follow Me V

We back it up with the MarineTraffic app on the tablet - so would be scouring both in fog or poor visibility.

For the wiring, I used trailer lighting cable for the cable run from chart table to cockpit binnacle and waterproof trailer lighting junction boxes with connector blocks in them. Once fitted and working, sprayed with WD40 and screwed shut.
They are a very cheap solution for tough multi-core cable and waterproof junctions.

 

[silver-fox]

Very informative thread guys - I learned quite a bit - so sincere thanks