QK-A026-plus Manual
V 1.0
8 of 22
2020
3.5. NMEA input and output connection
NMEA 0183 input/output ports allow for connection to NMEA 0183 instruments and a chart plotter.
The built-in multiplexer combines the input NMEA 0183 data (e.g., wind/depth/radar) with the AIS and
GPS data and sends the combined data stream to all outputs, including the NMEA 0183 output port.
NMEA 0183 default baud rates
‘Baud rates’ refer to the data transfer speed. When connecting two NMEA 0183 devices, both devices’
baud rates, must be set to the same speed.
•
A026+
input port’s default baud rate is 4800bps as it is usually connected to low speed NMEA
format data instruments, like heading, sounder, or wind/depth sensors.
•
A026+
output port’s default baud rate is 38400bps. The connected chart plotter should be
configured at this rate to receive the proper data as AIS data requires this higher speed.
These are the default baud rate settings and are most likely to be the baud rates required, however, both
baud rates are configurable if needed. Baud rates can be adjusted using the Configuration software.
(See Configuration section)
NMEA 0183 RS422 / RS232
This product uses the NMEA 0183-RS422 protocol (differential signal), however some chart plotters or
devices may use the older NMEA 0183-RS232 protocol (single-ended signal).
Check which protocol your connecting NMEA devices (e.g. Chart plotter/wind sensor) use. If you are
unsure whether your connecting devices use the NMEA 0183 RS422 or RS232, the input/output
connections on the device will give you some indication.
Unfortunately, manufacturers who use the older RS232 protocol are not consistent in their product
labelling. The following table may help you identify which protocol your product uses, however always
check the manual to be certain.
If your connecting device uses the older RS232 protocol, use a QK-AS03 Protocol Bridge for your
connection. The QK-AS03 connects and converts RS422 to the older RS232 and visa-versa, through a
simple connection with no configuration needed.
3.6. SeaTalk
1
Input
The built-in SeaTalk
1
to NMEA converter translates SeaTalk data into NMEA sentences. The SeaTalk
port has 3-Pin terminals for connection to the SeaTalk bus. Ensure the connection is correct before
powering up. An inaccurate connection could damage the A026+ and other devices on the SeaTalk Bus.
The SeaTalk converter converts the SeaTalk messages as outlined in the conversion table below. When
a SeaTalk message is received the A026+ checks if the message is supported. When the message is
recognized as being supported, the message is extracted, stored and converted to an NMEA sentence.
Any unsupported datagrams are ignored. These converted NMEA messages are filtered and then
combined with NMEA data received on the other inputs.
This function allows the NMEA multiplexer to listen on the SeaTalk bus. Only one SeaTalk input is
needed as the SeaTalk bus is a single-cable system that connects all instruments. The A026+ SeaTalk
to NMEA converter works in one direction only. NMEA sentences are not converted to SeaTalk.
Supported SeaTalk
1
Datagrams
SeaTalk
NMEA
Description
00
DBT
Depth below transducer
RS422 (Differential)
RS232 (single-ended)
TX+ and TX- / RX+ and RX-
TX+ and TX- (GND) / RX+ and RX- (GND)
TXa+ and TXa- (GND) / RXa+ and RXa- (GND)
Ve and
–Ve / Input +Ve and –Ve
Occasionally older NMEA 0183 RS232 devices are labelled like
RS422 (TX+ and TX- / RX+ and RX-) so check
the products’ manuals.
