Raymarine L1250DRC, Owner'S Handbook Manual

Page: 87 / 246

Chapter 4: System Setup 4-9
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Auto Mode
If you select Auto mode, the unit obtains the value of variation automatically,
normally from received data. The variation value that is used depends on the
data available and is selected in the following order of priority:
1. Variation value from the same source as the heading data:
• If heading data is being taken from NMEA, then variation is also taken
from NMEA
• If heading is taken from SeaTalk, then SeaTalk variation is used
2. Variation value from a different source:
• If heading data is being taken from NMEA, but no NMEA variation is
available, then variation is taken from SeaTalk
• If heading is taken from SeaTalk, but no SeaTalk variation is available,
then variation is taken from NMEA
3. A calculated variation value, using position data, if no SeaTalk or NMEA
value is available
4. The current manual variation value, if no SeaTalk or NMEA value and no
position data is available
Manual Mode
If you select Manual mode, by pressing either of the
MANUAL
keys, you can
specify the local variation value according to the area in which you are
operating. Press the appropriate
MANUAL
key to adjust the variation up or
down, to a maximum of 30° East or West.
This value is then transmitted to any other SeaTalk instruments on your
system. It is retained if you turn the display off and on again.
In Manual mode, incoming NMEA variation is ignored. However, if the
variation is changed on another SeaTalk instrument, the new value is used and
the manual value that is displayed is updated.
Note: The Manual variation value defaults to 0°, so it is important to set up a
value if variation is not available from an external source.
Bridge NMEA Heading
HD Series Fishfinders display bridge NMEA input data to the SeaTalk bus
(see
Section 2.9 ). The Bridge NMEA Heading option can be used to prevent
NMEA heading data being bridged onto the SeaTalk bus.
For example, if you have a course computer connected on SeaTalk and
NMEA, and an active compass connected on NMEA (for MARPA), SeaTalk
data overrides NMEA data in the course computer.
81213_1.book Page 9 Monday, March 17, 2003 1:14 PM