Si-tex SP38, Installation And Operation Manual, Page: 93 / 193

Sitex SP38 Installation and Operation Getting Started
Document PN 29010101 V1r0
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Backlight
There are two modes, DAY & NIGHT that allow you to select for the most convenient and
interference free viewing of the display.
Day
The backlight level is adjustable between 5% to 100%
Night
The backlight level is adjustable between 2% to 20%
Day / Night
Selects either the Day-time screen or the Night-time screen
Heading
This line allows you to choose which type of value – Degrees Magnetic or True – from an
NMEA source will be used by the autopilot for its Heading:
 “Auto” - the autopilot will automatically select whether to use Magnetic or
True, depending on which NMEA 2000 (PGN) sentences are received
(assuming all sentences have valid data).
 If the HDG PGN sentence is being received (regardless of whether HDM
and/or HDT PGN are also being received), then the autopilot will use a
Magnetic Heading (indicated on the display by an ‘M’ beside the boat’s actual
Heading value on the screen), and it will be the value in the HDG sentence.
 If only HDM and HDT are being received, or just HDT, then the autopilot
will use True Heading (indicated by a ‘T’), from the HDT sentence.
 If only HDM is being received, then the autopilot will use a Magnetic
Heading (indicated by an ‘M’), from that sentence.
 “True” - the autopilot will use True Heading from the HDT sentence. If
HDT is not being received, a Heading Error alarm will occur.

“Mag” - the autopilot will use Magnetic Heading from the HDG sentence, if
that is being received, or from HDM if only that is being received. If neither
HDG nor HDM are being received, a Heading Error alarm will occur.
There are three choices: Auto, True and Mag. Once the Auto is set, the Heading on the
screen will show True or Magnetic depending on the Heading Source.