High-Speed Serial Communication - Furuno FS-1575 Service Manual

7.6.4 High-speed Serial Communication

The Transceiver unit and the Control unit are connected with RS-485 half-duplex
communication interface. Data transmitted with this interface have command data and
FPGA-controlled voice data. Data are transceived in units of packets.
・Baud rate:
・Data length:
・Parity:
・Stop bit:
・Flow control:
Data transmission is divided into two categories taking 10 ms as one cycle. One
category is uplink transmission from the Transceiver unit to the Control unit, and the
other is downlink transmission from the Control unit to the Transceiver unit. This
transmission is controlled by the FPGA of each unit.
The FPGA of the Transceiver unit transmits downlink voice data after putting an idle
period of 20 bits. Subsequently, the FPGA puts a period of idle time again, and then
transmits command data. The FPGA of the Transceiver unit switches the RS-485 driver
from the transceiving state to the receiving state after completion of transmitting
command data.
The FPGA of the control unit treats the command data of downlink voice packets as a
pilot signal and initiates transmitting the data from the control unit upon receipt of it.
10 ms
RT -> CONT
0.1 ms
4.9 ms
Voice Data
(3.84 ms) (0.98 ms)
CONT unit
Changing RX to TX
RT unit
Changing TX to RX
Fig. 7.6.13 High-speed Serial Communication Timing Chart
• Configuration of downlink voice packet: From the Transceiver unit to the Control unit
Model name+Source+Destination+Command (Pilot)+SQ+Voice data (320 bytes)
• Configuration of uplink voice packet: From the Control unit to the Transceiver unit
Model name+Source+Destination+Command+Voice data (320 bytes)
• Configuration of command packet
Model name+Source+Destination+Command+Voice data (80 bytes)
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It is strictly prohibited to reproduce the document in whole or in part without prior written permission of FURUNO.
768 kbps
16 bits
N/A
1 bit
N/A
CONT -> RT
0.1 ms
4.9 ms
Voice Data
(3.82 ms) (0.98 ms)
CONT unit Tx start CONT unit Tx start
CONT unit
Changing RX to TX
RT unit
Changing TX to RX
7-66
Data A/B
2ms/div, 1v div
10 ms
RT -> CONT CONT -> RT
0.1 ms
4.9 ms
P + Voice / Data
7.6 T-CPU
4.9 ms
Voice / Data