ComNav P4 - NAV1 or NAV2 Port for General NMEA0183 Compass

ComNav P4 Installation and Operation Getting Started
Document PN 29010100 V1r0 - 109 -
NAV1 or NAV2 Port for general NMEA0183 Compass
For other NMEA compasses – such as a G2 or G2B GPS Compass – you should refer to
the setup and configuration instructions that are supplied with it.
Some points to keep in mind:
 For proper performance of the autopilot, the update rate of the
Heading sentences from the NMEA 0183 compass must be ~10 Hz
 Typically, you can set the sentence update rate in an NMEA
compass using a generic “terminal” program, or a product-specific
“control” program, on a PC (e.g., HyperTerminal, or Airmar’s
WeatherCaster™)
 Be sure to make that 10 Hz rate the “power-on default” rate (More
than 10 Hz is not useful, but at much less than that the autopilot
will not be able to maintain good control of the vessel’s steering).
 Whenever a NMEA 0183 compass is being used as the
Heading source, if valid Heading/Compass data sentences are
not received for ~3 seconds, an INVALID HEADING alarm will
occur.
 If you are going to be using only Magnetic Heading values, or only
True Heading values, then you only need to set the NMEA0183
compass to output the corresponding sentence – HDG or HDM for
Magnetic, HDT for True.
 If you wish to be able to switch between True and Magnetic (via
the Heading parameter in the System menu, then HDT and either
HDG or HDM should be enabled, with both HDT and HDG/HDM
at 10 Hz (see the section on “Bandwidth” later in this chapter).
 To verify that an NMEA compass is connected, look at the “NMEA
IN” LEDs in the Diagnostic section; the LED for the SPU’s NAV
input which the compass is connected to should be flickering.
NOTE: if the `A´ and `B´ wires are connected backwards, the LED will still flicker; but when
NAV1 or NAV2 is later selected at the Compass Source in the Standby menu, no Heading
will be displayed, and a NO HEADING alarm will occur. If this is the case, simply reverse
the `A´ and `B´ wires.