Furuno FS-1562 Manual page 329

Change the sending data pattern switch setting. If the on/off pattern of the LEDs
9.
CR11 to CR18 changes according to the sending data pattern switch setting, the
HSD modem is normal. The sending data pattern switches from left to right do not
correspond to the LEDs CR11 to CR18. The synchronization of both patterns
depends on the timing.
In the example of Figure 4 ;
Sending data pattern: ON/ON/OFF/ON/ON/OFF/ON/ON
Receiving data pattern:
OFF/OFF/OFF/OFF/ON/OFF/OFF/ON (normal) – left figure
ON/OFF/OFF/OFF/ON/OFF/OFF/OFF (abnormal) – right figure
Correct receiving pattern
Figure 4) Sending data pattern and receiving data pattern
10. Set the DTR switch to lower position to terminate the call.
11. Clear the registered telephone number:
Press * 5 1 * # on the No.1 telephone.
Figure 3) Front panel of HSD checker
H2-23
Sending data pattern switches
Wrong receiving pattern
FELCOM 81