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SHORT HAUL MODEM (SHM-FSK)
6. LED Indications
There are four LEDs on the front panel of the SHM-FSK. From left to right
they are:
Marking Function
CD Carrier Detect
RX Data flowing out of the SHM’s RS-232 port
TX Data flowing into the SHM’s RS-232 port
PWR Power connected
The first diagnostic LED is Carrier Detect. In full-duplex mode, the CD
LED must be ON on both units; in half-duplex, carrier-control mode, with RS-
232 cables connected, the CD LED will be ON on all Remote SHMs and OFF
on the Master SHM. (The Master CD LED will blink during operation as each
Remote SHM turns on its carrier to answer back to the Master). If the correct
CD LEDs are not ON, there is likely a carrier cable problem.
Assuming that the CD indication is correct, a loopback test is recommended
as described in Section 7.3.