MultiDyne FMX-125 - Manual (Page 5)

Instruction Manual, FMX-125 OPERATION and CONNECTIONS 5
CIRCUIT DESCRIPTION
TRANSMITTER SECTION
All data, contact closure and audio inputs are through the rear panel connectors. A
breakout board with screw terminals connects to the FMX-125 with a SCSI cable for data
and contact closure control. The RS-422/485 or RS-232 inputs are converted to TTL by
data convertors . A parallel to serial convertor (SERDES) converts the 8 control and 12
TTL data channels into one serial bit stream which is outputted to a fiber optic transceiver
module, modulated onto the fiber and sent to the other FMX-125.
The optional audio input is through the 68 pin SCSI connector from a headset mic
attached to the screw-terminal adapter breakout board. The analog audio is then sent to a
PCM (pulse code modulated) CODEC, where it is modulated into a TTL digital bit stream.
The digital audio bit stream is then sent to the SERDES as described above.
RECEIVER SECTION
The optical data is received by a fiber optic transceiver, demodulated and sent to a
serial to parallel convertor (SERDES) where it is de-multiplexed into the 12 TTL data
channels and 8 contact closure controls. The TTL channels are converted back into RS-
232 or RS-422/485 data by data convertors. The data is then outputted through the 68 pin
SCSI connector and the relay controls via the DB9 connectors to the breakout board.
In the case of audio, the TTL audio data from the SERDES is sent to a PCM
CODEC, and converted back into analog audio. It is sent to the breakout board via the
SCSI connectors.
INSTALLATION and PRECAUTIONS