NMEA 0183 is essentially a one wire system if you use the 12 volt ground. It has data + and ground, which is 99% of the time common with 12 volt ground.
Joe Della Barba From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Michael Brown Sent: Monday, January 13, 2014 2:20 PM To: cnc-list@cnc-list.com Subject: Re: Stus-List Autohelm St4000 how it should work with the GPS >Though something to consider is that the 0183 standard is for a total of 4 >wires to send and recieve. RX+GND and TX+GND. I didn't see where you >mentioned all those wires...sounded like too few. The ST4000 control head is NMEA IN only, two wires marks - +. > > So now, If I understand you correctly. I first have to create a route then to > start navigating a course or to a way-point. That should start > broadcasting a course to steer signal. then I in-gauge the st4000 by > pressing the +10 and -10 at the same time and it should start taking > direction from the Garmin? > does this sound correct? > With NEMA to the ST4000 it depends on what is being sent. Autohelm describes two scenarios, automatic acquisition and manual acquisition. Automatic - both cross track error and bearing to waypoint are sent Manual - only cross track error is sent With automatic get everything engaged and press +10 and -10 together. The manual requires that you get on course withing 5 degrees of the bearing to the waypoint and cross track less than 0.1 nm, then press +10 and -10 together. My guess is, and strictly a guess, is that the ST4000 uses its own fluxgate compass for navigation and takes some error correction from NEMA for cross track. >I know it has probably been done by others but I am not sure that I would >ever let my ST 4000 plus steer a course unattended based on transfer data >from my chart plotter. I wonder if that was what Autohelm was thinking, they seem to use the fluxgate compass. > Curt ? it?s been my experience that pretty much NO equipment uses the same > color wire for the same thing, even among equipment from the same > manufacturer. >You need to connect the NMEA0183 output wires from the GPS to the NMEA0183 >input wires on the > autopilot; TX+ and TX- on the Garmin to RX+ and RX- on >the Raymarine. >I can guarantee that the chances of any two of these wires having common >colors is about zero. Supposedly the + is Red and - is Blue, however Autohelm agrees with you. They are marked + and - only. Michael Brown Windburn C&C 30-1
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