Connect Simrad Autopilot to Garmin Chartplotter

[MV Wanderlust]

Good Morning Electronics Gurus! Hoping you can provide a "Dummies Guide" to walk me through connecting my Simrad AP28 autopilot to my Garmin 7612xsv Chartplotter. I'm pretty good with most electronics but this is the first time I've tackled something like this and don't want to make a mistake.

Our new-to-us boat has a Simrad AP28 autopilot that works perfectly. Press the Auto button and it holds a course. Pressing the Nav button yields a popup message that indicates no Nav input. According to the manual, this unit is NMEA 2000 and 0183 compatible. The boat also has a Garmin 7612xsv chartplotter. Going into Settings and checking connected devices, it only shows the 7612, no other devices.

Here is a photo of the back of the AP28:


The cable coming out of the Simnet port connects to this switch panel:




This is the autopilot computer:



This NMEA 2000 junction block is available near the autopilot head:


Also, this Garmin junction block is located inline. (I'm not sure what it does):


From what I've read, this should be pretty much Plug-n-Play but some expert guidance would be appreciated. Anyone familiar with these two units?

I can order a T connector and drop cable from Amazon:



Alternatively, some internet searching yielded a Simrad to NMEA connector cable (this or this) but it seems like that might already be what's plugged into the AP28.



I'm just not sure what to connect where to make the two units communicate without sending some random signal through the network that messes up the network. Any and all guidance will be appreciated.

Thanks.

John

[sailah]

John,

I don't have direct experience with your exact setup but I recently connected my older Simrad (AP11, J300X, HLD2000 drive) to my Garmin 942xs using NMEA0183.

I read the manual and it describes connecting 2 of the wires (Blue, Grey I think) from Garmin NMEA0183 to NMEA Input 2 (RX2+ & RX2-) on Simrad which I did with my Garmin cable.

Then in manual it describes how to do an NMEA check, by pressing both arrows and following instructions. I saw I was getting heading and XTE but not wind since I had not connected those yet. But the comms were established so now I can engage NAV and it should steer to my mark on GPS. That's in theory as I'm still on the hard.

I know you are working with a newer Simrad AP28 and NMEA2000, but I think the basic steps are likely similar. Have you tried the NMEA check on your Simrad head unit to see if it's getting anything?

I also ran an NMEA2000 network to connect my older Raymarine ST60+ instruments and it was pretty straight forward. Do the rest of your NMEA2000 connections work? I'm surprised that your Garmin shows only the 7612, it should list everything on NMEA2000 network I think. Mine shows Garmin 942xs, and the Ray Converter.

Have you verified you have power to the NMEA2000 backbone? This is usually a yellow cable and it's fused, so also check the fuse. If you have power, then maybe buy a long backbone cable and wire the Simrad to the Garmin with minimal other connections to see if you can establish comms with the Simrad. After that see if you can identify where it drops out.

Helps to trace the backbone and ensure all components are there. Power cable (breaker on? Which breaker is NMEA2000 power on?), end resistor connectors at ends of NMEA backbone?

Just my random thoughts having done this 2 days ago.

[nhschneider]

It was almost 10 years ago when I installed a complete Garmin electronics package (6208 chart plotter, radar, AIS, sonar, sailing instruments) and a Simrad AP28 autopilot. As I recall, I was amazed that everything came up and worked, first crack right out of the box. Prior to beginning the installation, I had set my expectations for a ‘challenging’ project but it was very easy.

Since then, we’ve completed our 48,000-mile circumnavigation and all of our electronics have performed almost flawlessly. Our Simrad steers far better than I can and draws very little power. By the way, we don’t have a self-steering wind vane installed.

My suggestion would be to read the installation manual, label all the wires carefully and take your time.

Good luck, fair winds and calm seas.

[CaptTom]

If both units support NMEA 2000, then it's plug-and-play. Yes, buy the "T" and drop cable from Amazon and just hook up whichever one isn't connected already.

Not sure what that Garmin connector box is, without seeing the pins. If it's some proprietary Garmin thing, ignore it. If it's NMEA 2000, well, there ya go.

If one or the other device only talks NMEA 0183, then it's just a matter of reading both manuals and seeing which color wire (may need an adapter with bare pigtails coming out) or which terminal is the receive, and which is the transmit, on each device. Connect the transmit of the MFD to the receive of the AP, and vice versa, and make sure each device is set to the same baud rate and other NMEA settings, and again, it should just work.

I have a Garmin 740s MFD talking happily to a Simrad AP50 over NMEA 0183. Zero problems.

[MV Wanderlust]

Originally Posted by CaptTom

I have a Garmin 740s MFD talking happily to a Simrad AP50 over NMEA 0183. Zero problems.

Good to know, Tom. Thanks. I'll start by picking up the cable to connector.

[Reefmagnet]

Simnet uses nmea 2000 protocol although the hardware specification is slightly different (which is probably more related to the simnet equivalent of dropper tees), but adding another nmea dropper and simnet to nmea adaptor cable will work. If it's nmea 0183 you need to deal with, you're best option is to use the at-10 simnet to nmea 0183 converter which has bidirectional functionality.

[MV Wanderlust]

Originally Posted by Reefmagnet

Simnet uses nmea 2000 protocol although the hardware specification is slightly different (which is probably more related to the simnet equivalent of dropper tees), but adding another nmea dropper and simnet to nmea adaptor cable will work. If it's nmea 0183 you need to deal with, you're best option is to use the at-10 simnet to nmea 0183 converter which has bidirectional functionality.

Thanks, RM. So, you’re thinking a T connector and this cable might do the trick?
https://www.westmarine.com/buy/simrad--2-nmea-2000-cable--11498557
I guess any electronic compass would be connected to the autopilot computer rather than the control head, right?

[Reefmagnet]

Originally Posted by CaptJohnEasley

Thanks, RM. So, you’re thinking a T connector and this cable might do the trick?
https://www.westmarine.com/buy/simra...able--11498557
I guess any electronic compass would be connected to the autopilot computer rather than the control head, right?

You need this, I suspect: Navico: SIMNET TO NMEA 2000 ADPTR KIT


Your compass will connect to the NMEA network, either 2000 or 0183 depending on which version you have. The AC-42 doesn't have provision for directly connecting a compass, IIRC. It's only the rudder feedback that connects directly to the AP drive but even this can be substituted with a NMEA version.


On my boat, I have a simnet backbone with some NMEA 2000 devices connected via adapters. The compass for my AP28/AC12 system is a SimRad unit that can output either NMEA 0183 or NMEA 2000, so it is just another device plugging into the network.

Everything on the NMEA 2000 network is accessible to any other device connected to the network, so it's always best to use NMEA 2000 stuff if a choice exists.


Edit: Yes, the cable you have the image for looks to be the right one. (I though it had the opposite NMEA connector on first look)

[MV Wanderlust]

Originally Posted by Reefmagnet

You need this, I suspect: Navico: SIMNET TO NMEA 2000 ADPTR KIT


Your compass will connect to the NMEA network, either 2000 or 0183 depending on which version you have. The AC-42 doesn't have provision for directly connecting a compass, IIRC. It's only the rudder feedback that connects directly to the AP drive but even this can be substituted with a NMEA version.


On my boat, I have a simnet backbone with some NMEA 2000 devices connected via adapters. The compass for my AP28/AC12 system is a SimRad unit that can output either NMEA 0183 or NMEA 2000, so it is just another device plugging into the network.

Everything on the NMEA 2000 network is accessible to any other device connected to the network, so it's always best to use NMEA 2000 stuff if a choice exists.


Edit: Yes, the cable you have the image for looks to be the right one. (I though it had the opposite NMEA connector on first look)

Awesome info! Thanks, RM.

[smac999]

that garmin black box is for your transducer.

you don't need any simnet cables if you already have a nmea 2000 backbone.

assuming there is currenty no nmea 2000 cable on the back of the garmin.

then you just need to add another simrad nmea 2000 tee. (the black garmin one will not line up wiht the simrad ones when you try to add it. the new grey ones might)

and that drop cable.

ignore any comments about nmea 183.

I can bet you that cable from the ap28 does not go to the DC panel. it will probably go to those nmea 2000 tees.

[Reefmagnet]

I think smac is right. I assumed the ap was connected independent of the nmea 2000 network and the mfd was connected to said network, but on looking back at the nmea tee photo, the rightmost dropper looks like it is the simnet adapter cable to the ap28. Just connecting the mfd to the existing network should solve the problem. I'd also suspect a compass will already be installed on the system, and the ap28 should be displaying bearings if it is working. If not, I think there is a diagnostic screen on the ap28 that shows the status of relevant connected components.

[MV Wanderlust]

Partial success! Upon closer examination, The AP28 autopilot was already connected to the NMEA 2000 backbone. Turned out the chartplotter was not. Add in a T connector and a drop cable from the chartplotter and the two of them can now see and communicate with each other.

Small, unexpected glitch: If you select or set a waypoint on the chartplotter and then select Go To, the Garmin draws a straight line to the waypoint and the AP28 receives signals and will start navigating. If you select Auto Guidance, the Garmin will draw a route to get there, based on the details specified about your boat, but the AP28 says no Nav data input.

Any ideas how to get the Garmin 7612xsv chartplotter to send nav data to the Simrad AP28 autopilot when the chartplotter is displaying a route created by Auto Guidance?

Thanks.

John

[MV Wanderlust]

Okay, a small update and to close out this thread...

I found out that Garmin sends proprietary data when you select Auto Guidance and it can only be read by a Garmin autopilot control head. So, only a Garmin + Garmin system can handle the automatic turns. However, you have the option of selecting a specific waypoint and selecting GoTo and that will send more generic signals that can be read by the Simrad autopilot. That's fine. That'll work. Select a waypoint over open water for a spot in the Keys or across the Gulf to the panhandle or from Ft Lauderdale to Bimini, press GoTo, and then on the AP28 autopilot, press the Nav button. The autopilot will keep you on course and, I believe, compensate for any cross-track errors. Should be good to go.

Thanks for all of the input and guidance, everyone!

[CaptTom]

Originally Posted by CaptJohnEasley

I found out that Garmin sends proprietary data when you select Auto Guidance and it can only be read by a Garmin autopilot control head.

My Garmin 740s is connected to my Simrad AP26 via NMEA 0183. It has no trouble sending course changes at waypoints along a route. Not sure if that's because it's a "proper" route and not auto-guidance, or if it's because it's NMEA 0183.

It would be good to know, because I just found out I can buy an adapter to hook my AP26 up to NMEA 2000. I probably wouldn't do that if I lost the ability to follow a route.

[MV Wanderlust]

Originally Posted by CaptTom

My Garmin 740s is connected to my Simrad AP26 via NMEA 0183. It has no trouble sending course changes at waypoints along a route. Not sure if that's because it's a "proper" route and not auto-guidance, or if it's because it's NMEA 0183.

It would be good to know, because I just found out I can buy an adapter to hook my AP26 up to NMEA 2000. I probably wouldn't do that if I lost the ability to follow a route.

Interesting. I’ll plot a proper route this week, upload it this weekend, and give it a try. I’ll post next week to let you know if it follows the manually-created route or not.