SIMRAD Robertson AP300DX to Furuno SCX21 integration question.

[DaleRox]

I have a SIMRAD Robertson AP300DX Auto Pilot (NEMA 0183), a SIMRAD NI300X NMEA 0183 to NEMA 2000 Interface Unit and a Garmin GPSMAP 8616 MFD Chart plotter. The question is should I wire the SCX21 into the SIMRAD NI300X 0183 interface or should I connect it directly into my NEMA 2000 Network? If I wire the SCX21 into the NEMA 2000 Network I will be able to run the SIMRAD Robertson AP300DX directly into the Garmin GPSMAP 8616 Chart plotter, eliminating the SIMRAD NI300X 0183 interface unit. The Chart Plotter does have a NEMA0183 connection along with a NEMA 2000 connection, what is your recommendation for connecting the SCX21

 

[jp498]

Your SCX21 does not have nmea2000. Simple as that. you will need the converter. You will also need a PC with an 0183 adaptor or a GP39 to program the SCX21. The autopilot will expect magnetic heading I think.

My recommendation is to change out the Simrad for a Furuno 711c and accessories. Then you can have nmea2000 between AP and garmin and 0183 to the sat compass without adaptors.

 

[DaleRox]

JP, thanks for the reply. My Garmin GPSMAP 8616 MFD Chart plotter has 0183 and 2000, does that make a difference? Also, should I return the SCX21 for an SCX20? I bought the SCX 21 because I thought it was both 2000 and 0183. Eventually, I will end up buying a new AP. However, for now, I tried to save money and bought a new display for the Robertson AP300DX, so I am in $5OO.00 for that. I'm new to all this, so please excuse my ignorance. I was trying to save a buck.

 

[jp498]

it would be simplest to get the SCX20 if you will have more things that have NMEA2000.

 

[DaleRox]

I have had the device for about two weeks and it's still in the box. Let me see if I can exchange the SCX21. Everything is NEMA 2000 except for the AP for now. Will I still need the GP39 to program the 21? Thanks.

 

[jp498]

A GP39 would not be needed or compatible to program a SCX20.

Unless you align it poorly or need some special settings, you do not need any programming on the SCX20.

The SCX21 however NEEDS some configuration as it puts out a ton of data and the normal NMEA0183 data rates of 4800 and 38400 can't handle it all. You have to configure which sentences go out which of the three ports, set port speeds, that sort of thing.

A Furuno MFD or a PC with Actisense software and NGT-1-USB (no longer available) could be used to program a SCX20 in the unlikely event. You could adjust which constellations it listens to, software correct physical alignment errors, etc... I've done it for multiple sat compasses on a boat and you want them both to match heading exactly, that sort of thing.

 

[DaleRox]

Ok, Great news and I feel like an idiot. So, I went out to Freeport this weekend to spend the weekend working on the Hatteras and to grab the SCX21 so I could return it but to my surprise I purchased a SCX20 not an SCX21. I have no clue why I thought I bought a SCX21. Once again, I actually have the SCX20.

So, everything I have is NEMA 2000 except for the Robertson AP300DX Autopilot. Since the Garmin MDF GPSMAP 8616 ChartPlotter has both NEMA 0183 and NEMA 2000 connections, can I plug the Autopilot directly into the Garmin Chartplotter? Also, I read a Furuno Radar and Furuno Auto pilot won't work with the Garmin Chartplotter. Is this true? I was going to get the Furuno Radar then eventually the Furuno Autopilot. I have to curb my spending because the better half is getting after me.

BTW → Thanks for your help

Update, according to Google Gemini and Microsoft Copilot:

Google Gemini → Yes, you should be able to directly connect a Robertson AP300DX Autopilot to a Garmin GPSMAP 8616 Chartplotter via NMEA 0183, but there are some important considerations:

Compatibility:

• Robertson AP300DX: The Robertson AP300DX is an older autopilot, and it primarily uses NMEA 0183 for communication. It would typically expect and output NMEA 0183 sentences for navigation and control.
• Garmin GPSMAP 8616: The Garmin GPSMAP 8616 chartplotter does have NMEA 0183 input and output ports. Garmin documentation confirms it has one NMEA 0183 input port (Rx) and one NMEA 0183 output port (Tx). It supports standard NMEA 0183 communication.

Wiring and Configuration:

1. Identify NMEA 0183 Wires:
   • Robertson AP300DX: You'll need to consult the installation manual for your specific AP300DX model to identify its NMEA 0183 transmit (Tx) and receive (Rx) wires, along with their polarity (+/- or A/B). Some older Robertson units might have "NAV IN" and "NAV RET" connections.
   • Garmin GPSMAP 8616: Garmin typically uses specific wire colors for NMEA 0183. For the 8616 series, the NMEA 0183 and audio cable usually has dedicated wires for NMEA 0183 Tx and Rx, often labeled with colors like gray/pink for Tx and white/orange for Rx. Refer to your 8616 installation manual for the precise wiring diagram and color codes.
2. Connect Talker to Listener:
   • Chartplotter (Talker) to Autopilot (Listener): The Garmin 8616 (Tx wires) will send navigation data (such as waypoints, routes, and cross-track error) to the Robertson AP300DX (Rx wires). This allows the autopilot to "track" a course set on the chartplotter.
   • Autopilot (Talker) to Chartplotter (Listener): The Robertson AP300DX (Tx wires) can send heading information to the Garmin 8616 (Rx wires), allowing the chartplotter to display the boat's current heading.
3. Polarity and Grounding:
   • NMEA 0183 uses a differential signal (A and B, or + and -). Ensure you connect the corresponding positive to positive and negative to negative terminals.
   • Both devices should be connected to a common power ground. Do not connect the NMEA 0183 data wires directly to power ground.
4. Baud Rate:
   • NMEA 0183 typically operates at 4800 baud (standard speed). Both devices need to be configured to the same baud rate. The Garmin 8616 allows you to set the communication format for its NMEA 0183 ports (e.g., "NMEA Std." for 4800 baud).
5. NMEA 0183 Sentences:
   • Ensure both devices support the necessary NMEA 0183 sentences for the desired functionality. For autopilot control, common sentences include:
     • From Chartplotter to Autopilot: APB (Autopilot B Information), APA (Autopilot A Information), XTE (Cross-Track Error), RMB (Recommended Minimum Navigation Information), XTR (Cross-Track Error - Obsolete).
     • From Autopilot to Chartplotter: HDG (Heading - Magnetic), HDM (Heading - Magnetic), HDT (Heading - True).

Potential Challenges/Considerations:

• Older NMEA 0183 Versions: The Robertson AP300DX is an older unit. It might support an earlier version of NMEA 0183. While the Garmin 8616 supports v2.1 and higher, it's generally backward compatible. However, if there are specific sentence formats or quirks with the older autopilot, some data might not translate perfectly.
• Single-Ended vs. Differential: NMEA 0183 can be "single-ended" (RS-232, one data wire and a common ground) or "differential" (RS-422, two data wires). Most modern devices are differential, but older ones might be single-ended. The Garmin 8616 supports both. You'll need to ensure your wiring matches the autopilot's output type.
• Data Loops: As one source mentions, avoid connecting 0183 in both directions if not necessary or if it leads to data loops, which can cause communication issues. However, for full autopilot functionality (chartplotter sending course, autopilot sending heading), bi-directional communication is usually desired.
• Troubleshooting: NMEA 0183 can sometimes be tricky to troubleshoot. Always double-check your wiring, polarity, and baud rate settings.

In summary, a direct NMEA 0183 connection is likely possible and is the intended method for interfacing the Robertson AP300DX with a modern chartplotter like the Garmin GPSMAP 8616. You will need to carefully follow the wiring instructions for both devices and configure the NMEA 0183 ports on the Garmin 8616.

Copilot's answer was more direct:
Yes, it is technically possible to connect a Robertson AP300DX Autopilot to a Garmin GPSMAP 8616 Chartplotter using NMEA 0183, but there are a few important considerations:

1. Compatibility​

• The Robertson AP300DX supports NMEA 0183 input for navigation data (e.g., waypoint, bearing, cross-track error).
• The Garmin GPSMAP 8616 can output NMEA 0183 data, but it primarily uses NMEA 2000. It has limited NMEA 0183 ports, so you’ll need to ensure one is available or use an adapter.

2. Wiring​

• Garmin’s NMEA 0183 wiring follows standard conventions:
  • TX+ (Out+) from Garmin → RX+ (In+) on Robertson
  • TX- (Out-) from Garmin → RX- (In-) on Robertson (or ground if not available)
• Garmin provides NMEA 0183 wiring guidelines here

3. Data Sentences​

• The Garmin must be configured to output the correct NMEA 0183 sentences that the AP300DX can interpret, such as:
  • APB – Autopilot Sentence "B"
  • RMB – Recommended Minimum Navigation Info
  • RMC – Recommended Minimum Specific GNSS Data
• You can configure this in the GPSMAP 8616 settings under Communications > NMEA 0183 Output.

4. Voltage Levels​

• Ensure both devices operate at compatible voltage levels (usually 12V). If not, a level shifter or opto-isolator may be needed.

5. Testing​

• After wiring and configuration, test the system by setting a waypoint on the Garmin and engaging the autopilot to see if it follows the route.