CS4
The CS4 multiplexed digital data connector is a ten-pin interface provides
interconnection between E1SC-MM (Media converter and Multiplexer) and the
E1SC-UIM (User Interface Module). It carries synchronous duplex 64 kbps
data, which contains the RS-232 asynchronous serial data, the analogue voice
channel and the alarm and control signals.
S3
Analogue voice channel momentary push button. Pushing the button will cause
the buzzer of the remote unit to buzz until the button is released. This button is
used to warn the remote side to switch its S4 switch to “hook-on” position after
a conversation is finished.
S4
Analogue voice channel hook switch, used to initiate a voice call. The normal
position of the switch is “hook-on”. If it is switched to “hook-off” position, the
buzzer of the remote device start buzzing while the green status LED starts
blinking at both sides. After changing the position of the switch at the remote
side to “hook-off” the buzzer will stop and both LED’s change to steady green.
The voice communication channel is now open. The channel can be close by
turning any of the to S4 switches to “hook-on” position.
FPGA logic
The FPGA (Field Programmable Gate Array) is the central controlling and
processing unit of the service channel module. It gathers the RS-232
asynchronous serial data, the analogue voice channel and the alarm and control
signals together and converts them into a synchronous 64 kb/s digital data
stream using unique framing and error correction protocol. After turning the
equipment ON the FPGA downloads its operating code, which takes
approximately 100 ms. Afterwards it initializes the voice channel and the RS-
232 circuits based on the DIP switch configuration. The FPGA uses clock
signals from the E1SC-MM module to start the multiplexed digital channel, the
receive and the transmit clock is independent from each other. As soon as the
circuits are synchronized, the E1SC-UIM is ready to work.
