Si-tex SP38, Installation And Operation Manual, Page: 66 / 193

Sitex SP38 Installation and Operation
Document PN 29010101 V1r0
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Navigation Data
The SP38 has the ability to accept Navigation Data and information formatted according to the
NMEA 0183 standard (version 3.00) or N2K in network configuration.
Many marine electronics devices (such as digital compasses, GPS receivers, chart-plotters, and
electronic charting systems, to name a few) have outputs complying with NMEA 0183.
Two such devices can be connected directly to the SP38’s SPU, by wiring them into the plug
mated to the receptacle labelled
J6 – NAV I/O .
The SPU also has an NMEA0183 output; it transmits the autopilot’s real-time Heading Data and
status information, for use by devices such as a radar display, a chart plotter or a navigation
program on a PC.
Refer to
Appendix 1 for more information on the NMEA 0183 sentences accepted and sent
by the system.
Figure 44 – Typical NMEA 0183 Connections
For proper operation, the connected device(s) must fully comply with NMEA 0183 Standard
(version 3.00):
 RS-422 electrical levels
 Baud rate: 4800
 Serial data format: 8 data bits, no parity, 1 stop bit

Correct NMEA sentence structure
 Checksums are optional, but must be valid if present
It may also be possible to use RS-232 electrical levels, in some cases, such as when using a
PC.
NOTE: The NAV2 port can optionally be run at 9600 Baud. To do so, you simply need to set the
other device to transmit at that rate. The SPU automatically sets the rate for this port, by looking
for “valid NMEA data” at all possible Baud rates.