ComNav 1001 - Page 17

14
CONNECTION FOR NON-1001 FLUXGATE COMPASSES
PLUG PIN
NUMBERS
1001
FLUXGATE
COMNAV
FUNCTION
NON-COMNAV
CONNECTIONS
1 BLUE COSINE COSINE *
2 RED DRIVE P1 N/C
3 BLACK DRIVE P2 N/C
4 SHIELD GROUND GROUND
5 WHITE REFERENCE REFERENCE
6 YELLOW SINE SINE *
7 GREEN +12V +12V
* If the reading is reversed, swap these two wires.
z In testing, the Brookes and
Gatehouse Halcyon 3 compass proved to
have a 'floating' reference. The reference
from the autopilot is also 'floating'. In
order for the interface to work, one of the
references must be fixed to a voltage.
The reference is fixed to +2.5 Volts inside
the autopilot by selecting Compass Type
3 (CPS.3) during the Dockside Set-up.
Compass Type 2 (CPS.2) should be
selected for all other fluxgate compasses.
z If the reading on the Digital Display
of the autopilot increases when the
heading of the vessel is decreasing,
reverse the Sine and Cosine leads.
z If the reading on the autopilot
display does not agree with the vessel's
actual heading, place the Master Select
Switch on the autopilot in the STANDBY
position and press the ADJUST key twice
to display the compass offset. Then press
either the up or down ARROW key to
adjust the offset by the amount of the
error.
z If the compass is self-
compensating, do not run the autopilot
compensation routine during Dockside
Set-up (press either the up or down
ARROW key when 'CAdJ' is shown on
the display).
z If the compass is not self-
compensating, run the autopilot
compensation routine to correct the
compass during Dockside Set-up (press
the ADJUST key when 'CAdJ' is shown
on the display).
MAGNETIC COMPASS
z The advantage of using a
magnetic compass with a fluxgate sensor
is that the autopilot is sensing the position
of the magnets on the compass card
rather than sensing the earth's magnetic
field directly.
z As the card of the compass has
physical inertia, it does not react
immediately to the changes in the
magnetic field it is immersed in, but only
to those changes which persist long
enough to overcome the resistance of the
compass card to movement.
This means that the compass is a more
stable heading reference than a fluxgate
compass. The magnetic compass will
largely ignore changes in the magnetic
field in the plane of the compass card
caused by vessel motion that the fluxgate
compass will react to.