Raymarine Ray230 Owner's Handbook Manual page 54

3-31
Operations
Operation at Power Up
At power up, the SeaTalk line is monitored for 1 minute. If a signal is
detected, the radio determines whether the data is valid. If valid, the data is
input, the NMEA indicator is displayed on the LCD of all handsets, and
the radio enters normal operation mode. The radio assumes all future data
is to be received on SeaTalk, so will not again monitor the NMEA line (until
the next time the handset goes through the power up sequence).
If no signal is detected on SeaTalk, the radio next monitors the NMEA line
for 1 minute. If a signal is detected on NMEA, the radio determines whether
the data is valid. If valid, the data is input, the NMEA indicator is displayed
on handsets, and the radio enters normal operation mode. The radio
assumes future data is to be received on NMEA, so will not again monitor
the SeaTalk line (until the next time the handset goes through the power up
sequence).
If no GPS signal is detected on either SeaTalk or NMEA after the 2 minute
polling period, a 5-second-long staccato alert tone is emitted and the NMEA
indicator flashes. All the position fields are set to 9's and the time and date
fields are set to 8's. The message NO GPS appears in the NAVSTAT screen,
although no positional data is displayed.
If at a later time valid data is received on NMEA, the data is input, the
NMEA indicator is displayed solid (no longer flashing), and the radio
enters normal operation mode. However, because the radio does not poll
for SeaTalk data after finding none within the first minute of powering on,
SeaTalk data would not be detected, even if valid, until the next time the
handset goes through the power up sequence.
Note: If SeaTalk positional data is not input within the first minute of
power up, you must cycle the handset OFF and ON again before a restored
signal can be detected.
Operation When the Signal is Lost or Becomes Invalid
If positional data that was previously detected becomes invalid or is no
longer detected, the radio polls the last detected line (SeaTalk or NMEA)
for 1 minute for it to be restored. The radio will not search for a signal on
SeaTalk if the signal was last seen on NMEA, or vice-versa.
Note: Because the radio only polls for the last detected input (SeaTalk or
NMEA) when a signal is lost, you must cycle the handset OFF and ON
again to properly detect positional data if the source is switched from
SeaTalk to NMEA or vice-versa.