WC-SERIAL USER MANUAL
76-02-103 Rev.C
Page 17 of 17
3.4 YELLOW LED ON, WAN Sync Alarm
The WAN SYNC alarm indicates that both transmit and receive clocks are present
but it is not possible to synchronise to the received serial. The WC-Serial expects to
receive an HDLC stream and SYNC is declared once flags have been detected and
the HDLC packet CRC error rate is low.
Check the serial cable is connected to the correct DCE (Modem)
Check the operating speed is supported by the interface type.
Check whether transmit clock inversion may help if a long (30m) X.21 cable is
being used.
Check the bit switches to ensure both units are using the same data state,
normal/inverted.
3.5 YELLOW FLASH, LINK LOSS FORWARDING
If Link Loss Forwarding is enabled, then if there is either a WAN Fault, or WAN sync
fault the LAN ports will be shut down to forward the Link Loss to the attached host
port.
Since LLF is caused by the WAN port being down, diagnose as per section 3.1
