ComNav Vector G2 & G2B Installation & Operation Wiring
Data Connections (Autopilot, GPS Display, Chartplotter, PC, etc.)
There are a number of ways to make the data connections required between the Vector G2
and other equipment on the vessel. See Figure 1, Figure 3and Figure 4for examples:
•The G2 is typically used with a ComNav Autopilot System (e.g., Commander P2,
Admiral P3, 2001, 5001, etc.), an optional ComNav Navigator G2 GPS Compass Display
System, and a generic Chartplotter or other type of Navigation System.
⇒A PC can be used, instead of the Navigator G2 Display, to configure the Vector
and/or monitor its status.
⇒A PC can be used, instead of a Chartplotter or other type of NMEA Navigation
equipment, to perform the “Navigation display & control” functions – setting
waypoints, etc.
Each of those connection schemes is described in more detail below. Other schemes may
also be possible on your vessel, or in your application of the G2.
All data communications from/to the G2 is done with serial data signals; there is also a
separate Alarm signal from the G2, using the contacts of a relay.
Serial Ports
The G2 has two serial ports, denoted as “Port A” & “Port B”.
The serial ports are full-duplex – they can transmit & receive simultaneously.
Outputs
The G2 can output an extensive set of standard and proprietary NMEA 0183 sentences on
the serial ports – geographic position & vessel heading data, status of the visible GPS
satellites, internal sensor data, Beacon data & status, and so on.
The G2 is factory-configured to output “general Navigation data” on Port A, and “Autopilot
data” on Port B. You may change the configuration, if you wish (see page 18 for full details).
Each port’s output (Transmit) is duplicated, with one connection at the RS-422 electrical
levels specified in the NMEA 0183 Standard, and the other at the RS-232 levels typically
used for computers. Both of the outputs from a Port always have the same data signals &
timing, irrespective of electrical level.
The choice of which electrical level(s) to use depends on the serial port type(s) supported by
the other equipment you wish to connect to. You may find that the other equipment needs
one or the other type, or a mixture of both.
RS-422
Most marine equipment will require using the G2’s RS-422 output(s) – for example, ComNav
Commander P2, Admiral P3 and 5001 Autopilots all require RS-422 levels on their Heading,
Speed & NAV input ports.
The G2’s RS-422 ports are Talkers (i.e., transmit only), in accordance with the NMEA 0183
Standard (version 3.01), and the matching international Standard IEC 61162-1.
RS-422 uses a pair of balanced signals1, in paired wires, with the ‘A’ signal on one wire & the
complementary ‘B’ signal on the other.
•It is necessary to maintain the correct signal polarity, when connecting one of the G2’s
RS-422 output wire pairs to an NMEA 0183 Listener:
⇒The G2 output port’s transmit data ‘A’ signal wire must be connected to the
receive data ‘A’ input terminal of the other device; similarly, the G2’s ‘B’ output
wire must be connected to the ‘B’ input terminal of the other device2.
1All the G2’s RS-422 output signals are referenced to the G2’s RS-232 Signal Ground, although it is usually not
necessary to connect that Ground to the other device, if using only the RS-422 outputs (see page 6).
2… the ‘A’ connection is often labelled “Positive” (or “+ve”, or just “+”), and the ‘B’ is “Negative” or “-ve” or “-“.
Document PN 29010078 V1.6 (Addendum #1) - 5 -
