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Service manual CS3000
Chapter 3: Loop processor board SPK-2 3-6
The circuit boards of the central unit
Document no.:
S-4-007.875/E
Prepared:
1995-03-17 Fia
Revision:
R4 2004-03-15 BM
© 2002, Consilium Marine AB
DC/DC converter
Power is taken from the back plane and converted via a galvanically isolated
DC/DC converter into 35V. The 35V is used to power feed the loops and is also
converted to 5V for the logic. The voltage feed is fused.
Control logic
Signals in the back plane for fuse fault, voltage fault and prim-alarm. All signals
are galvanically isolated between SPK-2 and the back plane.
LEDs
Indicating status of the system. Some LEDs are active only in service mode.
CPU, memory and watchdog
The CPU controls and supervises the communication on both loops and also
communicates with the LPK. The memory contains program code with initial
values for the loop units and also gives status information. The watchdog
supervises the CPU and activates a reset signal to the CPU in case of malfunction.
Address switch
An 8-pole DIP-switch deciding the physical address of the board.
RS485 LPK communication
One asyncronous channel of the processor is used for communication with the
LPK. These signals are adapted to the RS485 levels and are galvanically separated
from the back plane.
Service plug
RS232 channel used for service, debugging and downloading of code.
Earth fault measurement
Measuring positive and negative earth faults. Since the board is galvanically
separated from the rest of the system, the measurement is a local indication of earth
faults from the loops. Earth fault is not measured when the board is used for
connection of GSK.
Loop : EMC protection
Protecting the electronics from various EMC disturbances.
Loop: Short circuit protection
Contains two parts, one part automatically disconnecting the loop power when the
current consumption exceeds allowed limit and one part which is used to control
the power feed to the primary and/or secondary side of the loop.
Loop: Line power
Feeding the loop with correct DC voltage and current and adapting the loop to the
signalling used on IDA and NOSE loops.
Loop: Current measurement
Measuring the DC current which is fed to the loop.
Loop: Signal filter
Separating and filtering out IDA/NOSE communication from the DC supply
voltage on the loop.
Loop: Line modem
Sending and receiving IDA/NOSE communication. Communication with the
processor via serial channel.