NorthStar Echo Sounder 491 Operation Manual page 12

Using the 491 with
the 957/958
Page 8
4. Check that the FORMAT option is set to "490. " If not, set it
now.
Before starting, you should double-check that the navigator's
AUX port is set to the Sounder option:
1. Press STAR until you reach the OPTIONS/SERVICE INFO
screen.
2. Press the PORT SETUP OPTIONS key.
3. Check that the AUX PORT option is set to "Sounder. " If
not, set it now.
491 Echo Sounder Operations Manual